River Mole, Surrey
Encyclopedia
The River Mole is a tributary
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the River Thames
River Thames
The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 in southern England
Southern England
Southern England, the South and the South of England are imprecise terms used to refer to the southern counties of England bordering the English Midlands. It has a number of different interpretations of its geographic extents. The South is considered by many to be a cultural region with a distinct...

. It rises in West Sussex
West Sussex
West Sussex is a county in the south of England, bordering onto East Sussex , Hampshire and Surrey. The county of Sussex has been divided into East and West since the 12th century, and obtained separate county councils in 1888, but it remained a single ceremonial county until 1974 and the coming...

 near Gatwick Airport and flows north west through Surrey
Surrey
Surrey is a county in the South East of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire and Berkshire. The historic county town is Guildford. Surrey County Council sits at Kingston upon Thames, although this has been part of...

 for 80 km (49.7 mi) to the Thames
River Thames
The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 near Hampton Court Palace
Hampton Court Palace
Hampton Court Palace is a royal palace in the London Borough of Richmond upon Thames, Greater London; it has not been inhabited by the British royal family since the 18th century. The palace is located south west of Charing Cross and upstream of Central London on the River Thames...

. The river gives its name to the Surrey
Surrey
Surrey is a county in the South East of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire and Berkshire. The historic county town is Guildford. Surrey County Council sits at Kingston upon Thames, although this has been part of...

 district of Mole Valley
Mole Valley
Mole Valley is a local government district in Surrey, England. Its council is based in Dorking.The district, named after the River Mole, was formed on 1 April 1974, under the Local Government Act 1972, by a merger of the urban districts of Dorking and Leatherhead and most of the Dorking and Horley...

. The Mole crosses the North Downs
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. The North Downs lie within two Areas of Outstanding Natural Beauty , the Surrey Hills and the Kent Downs...

 between Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 and Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

, where it cuts a steep-sided valley, known as the Mole Gap, through the chalk. Much of the catchment area lies on impermeable rock (including Wealden Clay
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...

 and London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...

), meaning that the river level responds rapidly to heavy rainfall.

During the second half of the 20th century pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

 levels in the river were high, however since 1995 the water quality has improved dramatically and the Mole now boasts the greatest diversity of fish species of any river in England. Twelve Sites of Special Scientific Interest (SSSIs) that include wetland habitats are located within the Mole catchment area
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 and the stretch of river through Leatherhead has been designated a Local Nature Reserve
Local Nature Reserve
Local nature reserve or LNR is a designation for nature reserves in the United Kingdom. The designation has its origin in the recommendations of the Wild Life Conservation Special Committee which established the framework for nature conservation in the United Kingdom and suggested a national suite...

. The Mole Gap forms part of a Special Area of Conservation
Special Area of Conservation
A Special Area of Conservation is defined in the European Union's Habitats Directive , also known as the Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora...

 and is an SSSI of European importance.

The river has captured the imagination of several authors and poets, particularly since in very hot summers the river channel can become dry between Dorking and Leatherhead (most recently during the 1976 drought
1976 United Kingdom heat wave
The summer of 1976 was the hottest summer in the UK since records began. As well as the heat, Britain was in the middle of a severe drought.-Heatwave and drought effects:The temperature reached 80°F every day between 22 June and 16 July...

). In John Speed's
John Speed
John Speed was an English historian and cartographer.-Life:He was born at Farndon, Cheshire, and went into his father's tailoring business where he worked until he was about 50...

 1611 map of Surrey this stretch of the river is denoted by a series of hills accompanied by the legend "The river runneth under". However the river's name is unlikely to have derived from this behaviour: The Oxford Dictionary of English Place Names suggests that Mole either comes from the Latin mola (a mill) or is a back-formation
Back-formation
In etymology, back-formation is the process of creating a new lexeme, usually by removing actual or supposed affixes. The resulting neologism is called a back-formation, a term coined by James Murray in 1889...

 from Molesey (Mul's island). Domesday Book
Domesday Book
Domesday Book , now held at The National Archives, Kew, Richmond upon Thames in South West London, is the record of the great survey of much of England and parts of Wales completed in 1086...

 lists twenty mills
Watermill
A watermill is a structure that uses a water wheel or turbine to drive a mechanical process such as flour, lumber or textile production, or metal shaping .- History :...

 on the river in 1086, of which Sidlow Mill was the oldest, dating from Saxon times
History of Anglo-Saxon England
Anglo-Saxon England refers to the period of the history of that part of Britain, that became known as England, lasting from the end of Roman occupation and establishment of Anglo-Saxon kingdoms in the 5th century until the Norman conquest of England in 1066 by William the Conqueror...

.

Catchment area

The drainage area of the River Mole is 512 km² and forms 5% of the River Thames
River Thames
The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 catchment area above Teddington
Teddington
Teddington is a suburban area in the London Borough of Richmond upon Thames in south west London, on the north bank of the River Thames, between Hampton Wick and Twickenham. It stretches inland from the River Thames to Bushy Park...

. Annually the catchment area receives 761 mm rain each year, the greatest average level of rainfall is 800 mm rain around Crawley
Crawley
Crawley is a town and local government district with Borough status in West Sussex, England. It is south of Charing Cross, north of Brighton and Hove, and northeast of the county town of Chichester, covers an area of and had a population of 99,744 at the time of the 2001 Census.The area has...

. The Mole catchment reaches a maximum elevation of 265 m (869.4 ft) above Ordnance Datum
Ordnance Datum
In the British Isles, an Ordnance Datum or OD is a vertical datum used by an ordnance survey as the basis for deriving altitudes on maps. A spot height may be expressed as AOD for "above ordnance datum". Usually mean sea level is used for the datum...

 at Leith Hill
Leith Hill
Leith Hill to the south west of Dorking, Surrey, England, reaches above sea level, the highest point on the Greensand Ridge, and is the second highest point in south-east England, after Walbury Hill near Hungerford, West Berkshire, high....

 to the south west of Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

. There is only one aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

 in the drainage basin, at Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

, which means that the majority of the water in the river is from surface drainage, particularly from Gatwick Airport and the urban areas of Horley
Horley
Horley is a town in Surrey, England, situated south of the twin towns of Reigate and Redhill, and north of Gatwick Airport and Crawley.With fast links by train to London from Horley railway station, it has grown popular with commuters in recent years...

 and Crawley, and that the flow rate responds rapidly to rainfall.

Course

Upper Mole

The River Mole rises in Baldhorns Copse 0.7 km (0.434960915654865 mi) to the south of the village of Rusper
Rusper
Rusper is a village and civil parish in the Horsham District of West Sussex, England. It lies north of the town of Horsham and west of Crawley. Rusper is the centre of Rusper Parish which covers most of the northern area between Horsham and Crawley. Rusper is governed by the Horsham District...

 in West Sussex
West Sussex
West Sussex is a county in the south of England, bordering onto East Sussex , Hampshire and Surrey. The county of Sussex has been divided into East and West since the 12th century, and obtained separate county councils in 1888, but it remained a single ceremonial county until 1974 and the coming...

. The river flows initially southwards for 1 km (0.621372736649807 mi) to a small lake at Baldhorns Park, before running eastwards through a largely rural area towards Crawley. The first tributaries to join the young river drain the northernmost part of St Leonard's Forest
St Leonard's Forest
St. Leonard's Forest is at the western end of the Wealden Forest Ridge which runs from Horsham to Tonbridge, and is part of the High Weald Area of Outstanding Natural Beauty. It lies on the ridge to the south of the A264 between Horsham and Crawley with the villages of Colgate and Lower Beeding...

, between Horsham
Horsham
Horsham is a market town with a population of 55,657 on the upper reaches of the River Arun in the centre of the Weald, West Sussex, in the historic County of Sussex, England. The town is south south-west of London, north-west of Brighton and north-east of the county town of Chichester...

 and Crawley, although much of the Forest lies within the catchment of the River Arun
River Arun
The Arun is a river in the English county of West Sussex. Its source is a series of small streams in the St Leonard's Forest area, to the east of Horsham...

. The Mole skirts the northern suburbs of Crawley, where it is joined by its first major tributary Ifield Brook, which drains Ifield Mill Pond
Ifield Water Mill
Ifield Water Mill is a 19th-century weatherboarded watermill in the Ifield neighbourhood of Crawley, a town and borough in West Sussex, England. Built on the site of an earlier, smaller flour mill, which itself replaced an iron forge—one of many in the Crawley area—it fell into disuse in the 1930s...

.

The first gauging station
Stream gauge
A stream gauge, stream gage or gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water surface elevation and/or volumetric discharge are generally taken and observations of biota may also be...

 on the Mole is located to the south of Gatwick Airport (57 m above OD
Ordnance Datum
In the British Isles, an Ordnance Datum or OD is a vertical datum used by an ordnance survey as the basis for deriving altitudes on maps. A spot height may be expressed as AOD for "above ordnance datum". Usually mean sea level is used for the datum...

). The station was installed in 2005, replacing an earlier station located 200 m (200 yds) downstream. The mean flow is 0.33 m3/s and the river ran dry at this point for the first time in the summer of 1995. The Mole runs under the airport runway in a culvert completed in 1985. The course of the Mole within the airport perimeter has been altered several times since commercial flights began in 1945, however the meanders visible on the 1839 tithe map on the 1.5 km stretch immediately north of the runway were reinstated in 1999, in a £1.2 million project to facilitate airport expansion.

The Mole enters Surrey
Surrey
Surrey is a county in the South East of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire and Berkshire. The historic county town is Guildford. Surrey County Council sits at Kingston upon Thames, although this has been part of...

 to the south of Horley, where it meets the Gatwick Stream
Gatwick Stream
The Gatwick Stream is a tributary of the River Mole in southern England. The Gatwick Stream rises in Worth Forest in West Sussex and flows northwards through Tinsley Green to meet the Mole on the border between West Sussex and Surrey...

, a tributary draining Worth Forest to the southeast of Crawley. The second-largest Sewage Treatment Works (STW) in the Mole catchment is located on the Gatwick Stream 3 km (1.9 mi) upstream of the confluence with the Mole. Crawley STW discharges 15 Ml water per day and, in prolonged dry periods, accounts for up to 75% of the flow in the Mole downstream of the confluence. The mean flow measured at Horley gauging station (52 m above OD) is 1.4 m3/s. The Mole passes Horley to the west, flowing north towards Sidlow
Sidlow
Sidlow is a village in the parish of Salfords and Sidlow in the borough of Reigate and Banstead. It has a pub called the . The village also houses the Sidlow Bridge Centre which is a pupil referral unit.-External links:*...

 and entering a largely rural area. 0.7 km (0.434960915654865 mi) south of Sidlow the mean flow is measured as 2.21 m3/s at Kinnersley Manor gauging station (48 m above OD). The Earlswood Brook, a tributary draining the urban areas to the south of Reigate
Reigate
Reigate is a historic market town in Surrey, England, at the foot of the North Downs, and in the London commuter belt. It is one of the main constituents of the Borough of Reigate and Banstead...

 and Redhill
Redhill, Surrey
Redhill is a town in the borough of Reigate and Banstead, Surrey, England and is part of the London commuter belt. Redhill and the adjacent town of Reigate form a single urban area.-History:...

, joins the Mole at Sidlow. The largest STW in the Mole catchment (Reigate STW) discharges up to 118.5 Ml per day into the Earlswood Brook.

From Sidlow the Mole turns north west towards Brockham
Brockham
Brockham is a village in the Mole Valley district of Surrey, England. 'Broc-ham' is so called from the Anglo Saxon meaning 'river meadow by the brook' and is first recorded in 1241. It is often mistakenly believed that there is an association with badgers but this is a modern affectation from the...

. A number of minor tributaries join the river from the west and are typically second order streams
Strahler number
In mathematics, the Strahler number or Horton–Strahler number of a mathematical tree is a numerical measure of its branching complexity....

 draining the arable land between Horsham and Dorking. The 18th century weir at Betchworth
Betchworth
Betchworth is a village and civil parish in the Mole Valley district of Surrey, England. The village lies on the north bank of the River Mole, off the A25 road, about three miles east of Dorking and three miles west of Reigate. The village lay within the Reigate hundred.It was home to the now...

 was modified in 2004 to facilitate the installation of two 27.5 kW low-head
Low head hydro power
Low head hydro power applications use river current or tidal flows of 20 meters or less to produce energy. These applications do not need to dam or retain water to create hydraulic head; the head is only a few metres...

 hydro turbines
Water turbine
A water turbine is a rotary engine that takes energy from moving water.Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy...

. Approximately 90% of the energy generated is fed into the regional electricity grid, while the remainder is used to supply the Betchworth Park Estate, where the weir is situated. The river leaves the Wealden Clay
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...

 at Brockham, flowing briefly across the greensand and gault clay to Pixham
Pixham
Pixham is a village in Surrey located approximately 1 km north east of Dorking at the confluence of the River Mole and the Pipp Brook.-History:...

, 1 km (0.621372736649807 mi) north east of Dorking. A mean flow of 3.74 m3/s is measured at a fourth gauging station, located at Castle Mill (39 m above OD). At Pixham the Mole meets the Pipp Brook, a tributary draining the northern slopes of Leith Hill.

Mole Gap

Between Dorking and Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

 the Mole cuts a steep-sided valley (the Mole Gap) though the North Downs
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. The North Downs lie within two Areas of Outstanding Natural Beauty , the Surrey Hills and the Kent Downs...

, carving a 170 metres (557.7 ft) high river cliff on the western flank of Box Hill and a smaller 50 metres (164 ft) cliff at Ham Bank in Norbury Park
Norbury Park
Norbury Park is a swathe of land arranged around a small manor house near Leatherhead and Dorking, Surrey, which appears in the Domesday Book of 1086. The manor was also known as Northbury for some time....

. The sudden change from impermeable Wealden Clay
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...

 to permeable chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....

 and the increased gradient of the river (which drops 15 m in the six mile (10 km) stretch between Brockham and Leatherhead, compared to 3 m in 12 miles (19.3 km) between Horley and Brockham) allow the water table to drop below the bed of the river. Water is able to flow out of the river through swallow holes in the bed and banks, decreasing the volume of water carried in the river channel. The course of the river north of the village of Westhumble
Westhumble
Westhumble is a village situated north of Dorking in Surrey, England. Neighbouring villages include Mickleham and Great Bookham. The census area Mickleham, Westhumble and Pixham has a population of 1,932....

 was partially straightened when the Epsom to Horsham railway was built in 1837, with the removal of a small meander. The meander was reinstated in 1997, in an attempt to create a local nature reserve, although it has since become blocked by silt. The entirety of the Mole Gap lies within the Surrey Hills Area of Outstanding Natural Beauty
Surrey Hills AONB
The Surrey Hills is a Area of Outstanding Natural Beauty , located in Surrey, England. The AONB was designated in 1958 and covers one quarter of the county of Surrey...

.

Lower Mole

At Leatherhead, the Mole leaves the chalk and turns northwestwards to flow across impermeable London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...

 towards Cobham. The water table rises at this point and much of the water which drained out of the channel through the chalk returns through springs in the riverbed. The aquifer at Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

 is the only one in the entire catchment area. At Cobham the river swings round in a pronounced axe-head meander, passing Painshill Park
Painshill Park
Painshill Park , near Cobham, Surrey, England, is one of the finest remaining examples of an 18th century English landscape park. It was designed and created between 1738 and 1773 by the Hon. Charles Hamilton .Painshill Park is owned by Elmbridge Borough Council and managed by the Painshill Park...

 to the south. A 35 feet (10.7 m) diameter waterwheel raises water 5 metres (16.4 ft) from the river to feed the ornamental lake in the park.

From Painshill Park the river flows northwestwards towards the Thames, passing West End Common
Esher Commons
Esher Commons comprises several large wooded areas to the South West of Esher in the English county of Surrey. The designation includes Esher Common, Fairmile Common, West End Common and Oxshott Heath.-Geology and terrain:...

 and at Esher the mean flow of the river is 5.43 m3/s. In response to heavy flooding of East Molesey and Thames Ditton in September 1968
Great Flood of 1968
The Great Flood of 1968 was a flood caused by very heavy rain that struck South East England and France in mid-September 1968, with the worst on Sunday 15 September 1968, and followed earlier floods in South West England during July.-South West England:...

, the river was improved downstream of Albany Bridge to the Thames and new flood defences were constructed. North of Esher the Mole splits into two branches at the Island Barn Reservoir
Island Barn Reservoir
The Island Barn Reservoir lies south of the River Thames in England at West Molesey. The reservoir is large with a capacity of 992 million gallons and is managed by Thames Water. It is within the borough of Elmbridge and is surrounded by the River Mole to the west and the River Ember to the east...

 near Molesey: the northern (and smaller) branch continues as the River Mole and the southern branch is known as the River Ember
River Ember
The River Ember is a river in the county of Surrey, England. It is a distributary of the River Mole which splits in two at the Island Barn Reservoir to the South of East and West Molesey. The larger portion becomes the River Ember and flows in an easterly and then northerly direction around the...

. The two rivers flow either side of the reservoir, before flowing side by side in a north easterly direction, merging 400 m before the confluence
Confluence
Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...

 with the River Thames, on the reach above Teddington Lock
Teddington Lock
Teddington Lock is a complex of three locks and a weir on the River Thames in England at Ham in the western suburbs of London. The lock is on the southern Surrey side of the river....

. (For the purposes of the remainder of this article, the River Mole and the River Ember are treated as a single entity.)

Prior to the last Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

, the River Thames followed a more northerly route to the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

, from Reading
Reading, Berkshire
Reading is a large town and unitary authority area in England. It is located in the Thames Valley at the confluence of the River Thames and River Kennet, and on both the Great Western Main Line railway and the M4 motorway, some west of London....

 via Marlow
Marlow, Buckinghamshire
Marlow is a town and civil parish within Wycombe district in south Buckinghamshire, England...

, Chorleywood
Chorleywood
Chorleywood is a village and civil parish in the Three Rivers district of Hertfordshire in the United Kingdom. It had a population of 6,814 people at the 2001 census. The parish of Chorleywood as a whole has a population of 10,775. The town lies in the far south west of Hertfordshire, on the...

, St Albans
St Albans
St Albans is a city in southern Hertfordshire, England, around north of central London, which forms the main urban area of the City and District of St Albans. It is a historic market town, and is now a sought-after dormitory town within the London commuter belt...

, Hertford
Hertford
Hertford is the county town of Hertfordshire, England, and is also a civil parish in the East Hertfordshire district of the county. Forming a civil parish, the 2001 census put the population of Hertford at about 24,180. Recent estimates are that it is now around 28,000...

 and along the present Suffolk
Suffolk
Suffolk is a non-metropolitan county of historic origin in East Anglia, England. It has borders with Norfolk to the north, Cambridgeshire to the west and Essex to the south. The North Sea lies to the east...

-Essex
Essex
Essex is a ceremonial and non-metropolitan county in the East region of England, and one of the home counties. It is located to the northeast of Greater London. It borders with Cambridgeshire and Suffolk to the north, Hertfordshire to the west, Kent to the South and London to the south west...

 border. During this period, the Mole is thought to have merged with the River Wey
River Wey
The River Wey in Surrey, Hampshire and West Sussex is a tributary of the River Thames with two separate branches which join at Tilford. The source of the north branch is at Alton, Hampshire and of the south branch at both Blackdown south of Haslemere, and also close to Gibbet Hill, near Hindhead...

 near Byfleet
Byfleet
Byfleet is an inland island village forming a suburb of Woking in Surrey, England. It is in the east of the borough between the River Wey and the River Mole, and is within the M25 motorway....

 and then flowed in a north-easterly direction via Richmond
London Borough of Richmond upon Thames
The London Borough of Richmond upon Thames is a London borough in South West London, UK, which forms part of Outer London. It is unique because it is the only London borough situated both north and south of the River Thames.-Settlement:...

 to meet the proto-Thames near Ware in Hertfordshire
Hertfordshire
Hertfordshire is a ceremonial and non-metropolitan county in the East region of England. The county town is Hertford.The county is one of the Home Counties and lies inland, bordered by Greater London , Buckinghamshire , Bedfordshire , Cambridgeshire and...

. (Today the Mole and Wey are less than 2 km (1.2 mi) apart at their closest point south of Esher
Esher
Esher is a town in the Surrey borough of Elmbridge in South East England near the River Mole. It is a very prosperous part of the Greater London Urban Area, largely suburban in character, and is situated 14.1 miles south west of Charing Cross....

.) During the mid-Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 period (500 000 years before present
Before Present
Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...

), a large ice sheet built up across much of the East of England, reaching as far south as St Albans
St Albans
St Albans is a city in southern Hertfordshire, England, around north of central London, which forms the main urban area of the City and District of St Albans. It is a historic market town, and is now a sought-after dormitory town within the London commuter belt...

 and Chelmsford
Chelmsford
Chelmsford is the county town of Essex, England and the principal settlement of the borough of Chelmsford. It is located in the London commuter belt, approximately northeast of Charing Cross, London, and approximately the same distance from the once provincial Roman capital at Colchester...

, blocking the path of the proto-Thames. Glacial meltwater
Meltwater
Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...

 from the Anglian ice sheet, caused the Thames to divert southwards into the valley of the Mole-Wey river, thus adopting its present route through London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

.

Water quality

The water quality of the watercourses in the River Mole catchment area has improved dramatically since the 1990s. In 1990 the Environment Agency
Environment Agency
The Environment Agency is a British non-departmental public body of the Department for Environment, Food and Rural Affairs and an Assembly Government Sponsored Body of the Welsh Assembly Government that serves England and Wales.-Purpose:...

 assessed only 23% of the watercourses as Grade B (good) or better, but by 2002 60% had reached this standard. Investment in the Sewage Treatment Works within the catchment area has improved the quality of the discharges into the river and modifications to the runway and apron drainage systems at Gatwick Airport means that surface water is diverted to aerated pollution control lagoons and balancing ponds for treatment prior to being released into the river.

There have been a number of high profile pollution incidents of the river in recent years: In 2003, Gatwick Airport Ltd pleaded guilty to charges of allowing chemical pollution to enter the River Mole after a detergent, used to clean rubber and oil from the runway, was washed into Crawters Brook by airport workers. The Environment Agency
Environment Agency
The Environment Agency is a British non-departmental public body of the Department for Environment, Food and Rural Affairs and an Assembly Government Sponsored Body of the Welsh Assembly Government that serves England and Wales.-Purpose:...

 estimated that up to 5200 fish of 14 different species were killed as the pollution spread downstream. The airport was fined £30,000 by Lewes
Lewes
Lewes is the county town of East Sussex, England and historically of all of Sussex. It is a civil parish and is the centre of the Lewes local government district. The settlement has a history as a bridging point and as a market town, and today as a communications hub and tourist-oriented town...

 Crown Court
Crown Court
The Crown Court of England and Wales is, together with the High Court of Justice and the Court of Appeal, one of the constituent parts of the Senior Courts of England and Wales...

. In May 2003, sewage leaking from a pump operated by Thames Water leaked into the Stanford Brook killing a number of coarse fish in the Gatwick Stream.

Biodiversity

The Marsh Frog
Marsh Frog
The Marsh Frog is the largest frog native to Europe and belongs to the family of true frogs. It is very similar in appearance to the closely related Edible Frog and Pool Frog...

 Pelophylax ridibundus (a non-native species introduced from Europe in the 1930s) is now commonly found in the upper Mole and its tributaries around Newdigate
Newdigate
Newdigate is a village and civil parish in Surrey lying to the east of the A24 road running between Dorking and Horsham. Neighbouring villages include Charlwood, Capel and Coldharbour...

 and Gatwick. There is no evidence that the presence of the frogs has had a deleterious effect on indigenous
Indigenous (ecology)
In biogeography, a species is defined as native to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention. Every natural organism has its own natural range of distribution in which it is regarded as native...

 amphibians. A second non-native species, the Edible Frog
Edible Frog
The Edible Frog is a name for a common European frog, also known as the common water frog or green frog . It is used for food, particularly in France for the delicacy frog legs...

 (Pelophylax kl. esculentus) was introduced to a site at Newdigate
Newdigate
Newdigate is a village and civil parish in Surrey lying to the east of the A24 road running between Dorking and Horsham. Neighbouring villages include Charlwood, Capel and Coldharbour...

 in the early 1900s. It has recently been recorded in tributaries of the River Mole at Capel and Brockham
Brockham
Brockham is a village in the Mole Valley district of Surrey, England. 'Broc-ham' is so called from the Anglo Saxon meaning 'river meadow by the brook' and is first recorded in 1241. It is often mistakenly believed that there is an association with badgers but this is a modern affectation from the...

.
The River Mole has the most diverse fish population of any river in England. The Gatwick Stream is dominated by coarse fish such as brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....

, brook lamprey
Brook lamprey
The European brook lamprey is a small European lamprey species that exclusively inhabits freshwater...

, and eel
European eel
The European eel, Anguilla anguilla, is a species of eel, a snake-like, catadromous fish. They can reach in exceptional cases a length of 1½ m, but are normally much smaller, about 60–80 cm, and rarely more than 1 m....

. In 2003, the upper River Mole near Meath Green Lane, Salfords, was enhanced to create a gravel spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 area to encourage chub
European chub
The European chub , sometimes called the round chub, fat chub, chevin, pollard or simply "the" chub, is a freshwater fish of the family Cyprinidae...

 and dace
Common dace
The common dace , also known as the dace or the Eurasian dace, is a fresh- or brackish-water fish belonging to the family Cyprinidae. It is an inhabitant of the rivers and streams of Europe north of the Alps as well as in Asia. It is most abundant in France and Germany, and has also spread to...

 in addition to roach. In 1974 zander
Zander
Zander is a species of fish. The scientific name is Sander lucioperca , and it is closely allied to perch. Zander are often called pike-perch as they resemble the pike with their elongated body and head, and the perch with their spiny dorsal fin. Zander are not, as is commonly believed, a pike and...

, a non-indigenous coarse fish native to Europe, were introduced legally to Old Bury Hill Lake which supplies the Pippbrook. Zander have been caught in the Lower Mole below Dorking since the 1980s.

In the Mole Gap between Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 and Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

 the river supports populations of chub, dace, barbel
Barbel (fish species)
Barbels are group of small carp-like freshwater fish, almost all of the genus Barbus. They are usually found in gravel and rocky-bottomed slow-flowing waters with high dissolved oxygen content. A typical adult barbel will range from 25 to 100 cm in length and weigh anywhere between 200 g...

, brown trout. Both barbel and brown trout are extremely sensitive to water quality and pollution. Below Leatherhead the river has historically supported larger predatory fish including chub, perch
European perch
The European perch, Perca fluviatilis, is a predatory species of perch found in Europe and Asia. In some areas it is known as the redfin perch or English perch, and it is often known simply as perch. The species is a popular quarry for anglers and has been widely introduced beyond its native area,...

, pike
Northern Pike
The northern pike , is a species of carnivorous fish of the genus Esox...

, and eels, however in recent years chub and eel numbers have begun to decline. North of Esher the old river channel is dominated by floating pennywort
Hydrocotyle umbellata
Hydrocotyle umbellata, is an aquatic plant that thrives in wet, sandy habitat. Its English common name is manyflower marsh pennywort or dollarweed. It is native to North America and parts of South America. It can also be found growing as an introduced species and sometimes a noxious weed on other...

, a highly invasive weed, which cuts off all light to the river bed, reducing oxygen levels and resulting in a poor habitat for fish. The Ember flood relief channel has a diverse fish population, including chub, dace, roach, bleak, large pike and barbel. At the confluence
Confluence
Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...

 of the Mole and the River Thames it is possible to catch brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....

 and flounder
Flounder
The flounder is an ocean-dwelling flatfish species that is found in coastal lagoons and estuaries of the Northern Atlantic and Pacific Oceans.-Taxonomy:There are a number of geographical and taxonomical species to which flounder belong.*Western Atlantic...

.

The geographical distribution of many species of invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

 in the river reflects the geology of the catchment area. Viviparid snails and water scorpions (of the genus Nepidae) are commonly found where the river runs over the London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...

. Crayfish are common in areas associated with high alkalinity particularly around Brockham
Brockham
Brockham is a village in the Mole Valley district of Surrey, England. 'Broc-ham' is so called from the Anglo Saxon meaning 'river meadow by the brook' and is first recorded in 1241. It is often mistakenly believed that there is an association with badgers but this is a modern affectation from the...

 and the tributaries which run over the Wealden Clay
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...

 provide an excellent habitat for stoneflies, caddisflies
Trichoptera
The caddisflies are an order, Trichoptera, of insects with approximately 12,000 described species. Also called sedge-flies or rail-flies, they are small moth-like insects having two pairs of hairy membranous wings...

, fast swimming mayflies and riffle beetles.
The Beautiful Demoiselle
Beautiful Demoiselle
The Beautiful Demoiselle is a European damselfly. It is often found among fast-flowing waters.-Identification:The male has dark brown-black wingtips with blue veins. Immature insects often have much paler, browner wings...

 (Calopteryx virgo) disappeared from the River Mole during the 1960s owing to deteriorating water quality, but has since recolonised. The White-legged Damselfly
White-legged Damselfly
The White-legged Damselfly or Blue Featherleg, Platycnemis pennipes, is a damselfly of slow-flowing, muddy waters. It occurs from the Atlantic to Siberia and is often abundant throughout its range.-Morphology:P. pennipes is about long...

 (Platycnemis pennipes) is also found along the river and the Downy Emerald
Downy Emerald
The downy emerald is a species of dragonfly. It is metallic green and bronze in color, and its thorax is coated with fine hairs, hence its name. Like most other emeralds, the downy emerald has bright shiny green eyes...

 (Cordulia aenea) is found between Box Hill
Box Hill, Surrey
Box Hill is a summit of the North Downs in Surrey, approximately south west of London. The hill takes its name from the ancient box woodland found on the steepest west-facing chalk slopes overlooking the River Mole. The western part of the hill is owned and managed by the National Trust, whilst...

 and Leatherhead. The Mole is one of only three locations in England where the River Shingle Beetle Meotica anglica is found.

A nationally scarce species which is locally common on the River Mole is the Greater Dodder Cuscuta europaea.

Conservation

The Mole catchment area
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 includes twelve Sites of Special Scientific Interest (SSSIs) which include wetland habitats and the stretch of river through Leatherhead has been designated a Local Nature Reserve
Local Nature Reserve
Local nature reserve or LNR is a designation for nature reserves in the United Kingdom. The designation has its origin in the recommendations of the Wild Life Conservation Special Committee which established the framework for nature conservation in the United Kingdom and suggested a national suite...

. The Mole Gap forms part of a Special Area of Conservation
Special Area of Conservation
A Special Area of Conservation is defined in the European Union's Habitats Directive , also known as the Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora...

 and is an SSSI of European importance.

The stretch of river between Thorncroft Manor (1 km south of Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

) and River Lane in Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

 has been designated a Local Nature Reserve. Although much of the surrounding land has been taken by residential and commercial development, this section of the Mole supports 20 different mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

 species, 20 butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 species and 15 species of dragonfly
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...

. The geology of the local area is complex, since the river leaves the chalk of the Mole Gap at this point and flows over gravel and clay, creating a patchwork of different habitats including scrub, woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

, hedges, banks, and meadow
Meadow
A meadow is a field vegetated primarily by grass and other non-woody plants . The term is from Old English mædwe. In agriculture a meadow is grassland which is not grazed by domestic livestock but rather allowed to grow unchecked in order to make hay...

s as well as the water itself. The river also provides a corridor for wildlife through the centre of Leatherhead.

The West End Common forms part of the Esher Commons
Esher Commons
Esher Commons comprises several large wooded areas to the South West of Esher in the English county of Surrey. The designation includes Esher Common, Fairmile Common, West End Common and Oxshott Heath.-Geology and terrain:...

, owned and managed by Elmbridge Borough Council
Elmbridge
Elmbridge is a local government district and borough in Surrey, England. Its council is based in Esher. The district has only one civil parish, which is Claygate...

. The River Mole forms the western boundary of the common, flowing past a steep sandy area known locally as The Ledges. Plant species typical of ancient woodland are found in this area, including bluebells
Common Bluebell
Hyacinthoides non-scripta, commonly known as the common bluebell, is a spring-flowering bulbous perennial plant. -Taxonomy:...

 (Hyacinthoides non-scriptus), Marsh Marigolds (Caltha palustris) and Golden Saxifrages
Saxifrage
Saxifraga is the largest genus in the family Saxifragaceae, containing about 440 species of Holarctic perennial plants, known as saxifrages. The Latin word saxifraga means literally "stone-breaker", from Latin + ...

 (Chrysosplenium sp.). Large Bittercress
Cardamine
Cardamine , is a large genus in the family Brassicaceae. It contains more than 150 species of annuals and perennials. The genus grows worldwide in diverse habitats, except in the Antarctic. Genus Dentaria is a synonym for Cardamine.The leaves can have different forms, going from minute to...

 (Cardamine amara) and the non-native Himalayan Balsam
Himalayan Balsam
Impatiens glandulifera is a large annual plant native to the Himalayas. Via human introduction it is now extant across much of the Northern Hemisphere.-Etymology:...

 (Impatiens glandulifera) are also found along the river banks.

Upper Mole (geology)

The Mole above Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 drains an area of 340 km² (131.3 sq mi), of which approximately 60% is on Wealden Clay
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...

 or Atherfield Clay, 20% is on Tunbridge Wells Sand and 20% is on greensand
Greensand
Greensand or Green sand is either a sand or sandstone, which has a greenish color. This term is specifically applied to shallow marine sediment, that contains noticeable quantities of rounded greenish grains. These grains are called glauconies and consist of a mixture of mixed-layer clay...

. The upper Mole catchment is dominated by a single broad terrace, which runs continuously from the entry to the Mole Gap as far south as Tilgate Forest. Above Meath Green (near Horley
Horley
Horley is a town in Surrey, England, situated south of the twin towns of Reigate and Redhill, and north of Gatwick Airport and Crawley.With fast links by train to London from Horley railway station, it has grown popular with commuters in recent years...

), the terrace corresponds to the flood plain of the river, however from this point downstream to Brockham, the river cuts a narrow trench no more than 150m wide. A similar trench is runs up several of the Mole's tributaries, notably along Deanoak Brook which follows a local strike
Strike and dip
Strike and dip refer to the orientation or attitude of a geologic feature. The strike line of a bed, fault, or other planar feature is a line representing the intersection of that feature with a horizontal plane. On a geologic map, this is represented with a short straight line segment oriented...

. The presence of the trench protects the land from flooding rendering it suitable for agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

.

Mole Gap (geology)

Between Dorking and Leatherhead the Mole cuts a steep-sided valley through the North Downs, creating a 170 metres (557.7 ft) high river cliff on the western flank of Box Hill. The bedrock is permeable chalk and the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

 lies permanently below the level of the riverbed, allowing water to drain out of the river through swallow holes in the bed and banks. The amount water lost from the river is significant and in very hot summers the channel can become dry between Mickleham and Thorncroft Manor, (recorded most recently in 1949 and 1976). At Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

, the river leaves the chalk and flows across impermeable London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...

. It is at this point that the water table rises sufficiently, enabling the water to flow back into the main river channel.

In a survey in 1958, the geologist C.C. Fagg, identified twenty five active swallow holes between Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 and Mickleham
Mickleham, Surrey
Mickleham is a village and civil parish between the towns of Dorking and Leatherhead in Surrey, England covering . The parish includes the hamlet of Fredley.-History:Mickleham lies near to the old Roman road known as Stane Street...

, finding that most were only a few centimetres in diameter and were located in the vertical banks of the river below the waterline. Most holes were difficult to observe in times of normal or heavy flow and were susceptible to silting up as new holes were continually being formed. A few much larger swallow holes were also observed separated from the main river by a channel of about a metre. An area to the west of the Burford Bridge Hotel
Burford Bridge Hotel
Burford Bridge Hotel is an historic hotel in the village of Mickleham, Surrey, England. It is to the south of Leatherhead and north of Dorking at the foot of Box Hill on the River Mole. It is now owned by Mercure Hotels.- History :...

 containing half a dozen of these larger swallow holes was located along the projected course of the A24 Mickleham Bypass
A24 road (Great Britain)
The A24 is a major road in England. It runs south from Clapham in southwest London through Morden before entering Surrey and heading through Ewell, Epsom, Ashtead, Leatherhead and Dorking...

. During the construction of the bypass in 1936. Initially the surveyors attempted to fill the holes with rubble to prevent the foundations of the new road subsiding. However this proved to be impractical and they were instead covered by concrete domes (up to 18 m in diameter) each fully supported by the surrounding chalk and provided with a manhole and access shaft to allow periodic inspections. During the late 1960s the domes were reopened and inspected and the alluvium in the largest swallow hole was observed to have subsided by 1.5 metres (4.9 ft) under the centre of one of the domes. When the Dorking to Leatherhead railway was constructed in 1859, a fossilised swallow hole was discovered in the cutting at the south end of Box Hill and Westhumble railway station, suggesting that even in its early history, the river possessed swallow holes.

The author
Author
An author is broadly defined as "the person who originates or gives existence to anything" and that authorship determines responsibility for what is created. Narrowly defined, an author is the originator of any written work.-Legal significance:...

, Daniel Defoe
Daniel Defoe
Daniel Defoe , born Daniel Foe, was an English trader, writer, journalist, and pamphleteer, who gained fame for his novel Robinson Crusoe. Defoe is notable for being one of the earliest proponents of the novel, as he helped to popularise the form in Britain and along with others such as Richardson,...

 (who attended school in Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 and probably grew up in the village of Westhumble
Westhumble
Westhumble is a village situated north of Dorking in Surrey, England. Neighbouring villages include Mickleham and Great Bookham. The census area Mickleham, Westhumble and Pixham has a population of 1,932....

) described the swallow holes in the River Mole in his book A tour thro' the Whole Island of Great Britain
A tour thro' the Whole Island of Great Britain
A tour thro' the whole island of Great Britain is an account of his travels by English author Daniel Defoe, first published in three volumes between 1724 and 1727....

 (first published in 1724):

.. the current of the river being much obstructed by the interposition of those hills, called Box Hill ... it forces the waters as it were to find their way through as well as they can; and in order to do this, beginning, I say, where the river comes close to the foot of the precipice of Box-Hill, called the Stomacher, the waters sink insensibly away, and in some places are to be seen (and I have seen them) little channels which go out on the sides of the river, where the water in a stream not so big as would fill a pipe of a quarter of an inch diameter, trills away out of the river, and sinks insensibly into the ground. In this manner it goes away, lessening the stream for above a mile, near two, and these they call the Swallows.


Not all of the water removed from the river by the swallow holes, is returned to the channel at Leatherhead
Leatherhead
Leatherhead is a town in the County of Surrey, England, on the River Mole, part of Mole Valley district. It is thought to be of Saxon origin...

. The chalk aquifer also feeds the springs at the southern end of Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

 Mill Pond, which have never been known to run dry. A survey carried out in March 1883, estimated that the Fetcham springs were producing approximately 3.6 million gallons of water every day. A second survey performed in 1948, estimated that the same springs were yielding approximately five million gallons of water a day. The water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

 in the chalk of the Wey Gap
River Wey
The River Wey in Surrey, Hampshire and West Sussex is a tributary of the River Thames with two separate branches which join at Tilford. The source of the north branch is at Alton, Hampshire and of the south branch at both Blackdown south of Haslemere, and also close to Gibbet Hill, near Hindhead...

 is significantly higher than might be expected from natural rainwater percolation alone. It has been suggested that a proportion of the excess water originates from the Mole Gap.

Lower Mole (geology)

At Leatherhead the river leaves the chalk bedrock, moving on to London Clay
London Clay
The London Clay Formation is a marine geological formation of Ypresian age which crops out in the southeast of England. The London Clay is well known for the fossils it contains. The fossils from the Lower Eocene indicate a moderately warm climate, the flora being tropical or subtropical...

. The river meanders across an alluvial plain
Alluvial plain
An alluvial plain is a relatively flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms...

 of between 400 m and 800 m wide towards Cobham, where it begins to descend to a lower flood plain which in turn broadens to the axehead meander at Painshill Park. At the east end of Painshill Park, the lower flood plain abruptly narrows to form a narrow trench approximately 60 m wide, in which the river runs northwards for 6.5 km (4 mi) towards Hersham, where the river enters the flood plain of the River Thames.

There are a series of gravel deposits laid down by the river above the London Clay between Cobham, Walton-on-Thames
Walton-on-Thames
Walton-on-Thames is a town in the Elmbridge borough of Surrey in South East England. The town is located south west of Charing Cross and is between the towns of Weybridge and Molesey. It is situated on the River Thames between Sunbury Lock and Shepperton Lock.- History :The name "Walton" is...

 and Esher. The depth of the deposits generally varies from 2.5 m (8.2 ft) to 7 m (23 ft), and the lower layers are generally highly compacted and cemented together with brick-red iron oxide, whilst the upper layers are loosely packed with angular flints and sand. Remains of a further gravel terrace containing both cherts and flints to a depth of 4 m (13.1 ft) are located along the side of St George's Hill.

Etymology

The name of the river is first recorded in the Red Book of Thorney in 983 AD as Emen and in the 1005 AD Cartulary of the Abbey of Eynsham as both Emen and Æmen. Variations in the name are recorded throughout the medieval period and the river appears as Amele in Domesday Book and subsequently as Emele in twelfth and thirteenth century Court Roles. This name is probably derived from the Old English word æmen meaning misty or causing mists. The name of the River Ember probably has its origins in this name.

The use of the name Mole for the river does not appear until the sixteenth century, first occurring as Moule in Harrison's
William Harrison (clergyman)
William Harrison was an English clergyman, whose Description of England was produced as part of the publishing venture of a group of London stationers who produced Raphael Holinshed's Chronicles...

 Description of Britain of 1577. The antiquarian William Camden
William Camden
William Camden was an English antiquarian, historian, topographer, and officer of arms. He wrote the first chorographical survey of the islands of Great Britain and Ireland and the first detailed historical account of the reign of Elizabeth I of England.- Early years :Camden was born in London...

 uses the Latinized form Molis in the 1586 edition of Britannia and Michael Drayton
Michael Drayton
Michael Drayton was an English poet who came to prominence in the Elizabethan era.-Early life:He was born at Hartshill, near Nuneaton, Warwickshire, England. Almost nothing is known about his early life, beyond the fact that in 1580 he was in the service of Thomas Goodere of Collingham,...

 is the first to use Mole in his poem Poly-Olbion published in 1613. The Oxford Dictionary of English Place Names suggests that Mole either comes from the Latin mola (a mill) or is a back-formation
Back-formation
In etymology, back-formation is the process of creating a new lexeme, usually by removing actual or supposed affixes. The resulting neologism is called a back-formation, a term coined by James Murray in 1889...

 from Molesey (Mul's island). In John Rocque's
John Rocque
John Rocque was a surveyor and cartographer.Rocque was born no later than 1709, since that was the year he moved to England with his parents, who were French Huguenot émigrés...

 1768 map of Surrey, the name Moulsey River is used.

Archaeology

In common with much of the rest of the Weald, the earliest evidence of human settlement along the Upper Mole is from the Mesolithic Period
Mesolithic
The Mesolithic is an archaeological concept used to refer to certain groups of archaeological cultures defined as falling between the Paleolithic and the Neolithic....

 (20 000 - 7000 BC). Mesolithic sites at Wonham, Flanchford and Sidlow. Finds at Wonham include arrowheads and a plano-convex knife. The Lower Mole appears to have been settled during the same period and a flint axe dating from Mesolithic period found on spit of land close to River Mole in Cobham in 1965. Remains of a flat-bottomed dug-out canoe were found at the confluence of the Mole and Thames in 1877 by a local boatman. The canoe is preserved at the Pitt Rivers Museum
Pitt Rivers Museum
The Pitt Rivers Museum is a museum displaying the archaeological and anthropological collections of the University of Oxford in Oxford, England. The museum is located to the east of the Oxford University Museum of Natural History, and can only be accessed through that building.The museum was...

 in Oxford
Oxford
The city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...

.

The Mole Gap and North Downs do not appear to have been settled until the late Stone Age: A large axe, typical of a "rough-out" axe produced during the Neolithic
Neolithic
The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...

 period, which was discovered in 1952 during building work in Westhumble, A Flint Mine of the same period has been discovered at East Horsley along with neolithic flakes of flint at Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

 and Headley Heath
Headley, Surrey
Headley is a small village and civil parish in Surrey, England covering 675 hectares.The village is bordered to its west by Leatherhead, to the north by Ashtead and Langley Vale, Walton-on-the-Hill to the east and to its south by Box Hill. It is just outside the M25 motorway encircling...

.

Significant Bronze Age
Bronze Age
The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Chronologically, it stands between the Stone Age and Iron Age...

 finds include a bronze sword found close to the river north of Amberley Farm near Charlwood and a small hoard of weaponry consisting of two palstave axes
Palstave
A Palstave is a type of early bronze axe. It was common in the mid Bronze Age in north, western and south-western Europe. In the technical sense, although precise definitions differ, an axe is generally deemed to be a palstave if it is hafted by means of a forked wooden handle kept in place with...

 and a scabbard chape was discovered in 2003 in Norbury Park close to Ham Bank.

Navigation

It is not clear to what extent the Mole was used for navigation in the past: In the late 13th century, Thorncroft Manor (south of Leatherhead) purchased a shout, a type of boat up to 16 metres (52.5 ft) in length used to carry produce to market and it has been suggested that stone cut from quarries in Reigate was transported to London via the river.

During the 17th century, two bills came before parliament to make sections of the river navigable. The first, in 1663, was passed by the House of Commons
British House of Commons
The House of Commons is the lower house of the Parliament of the United Kingdom, which also comprises the Sovereign and the House of Lords . Both Commons and Lords meet in the Palace of Westminster. The Commons is a democratically elected body, consisting of 650 members , who are known as Members...

 but was defeated in the House of Lords
House of Lords
The House of Lords is the upper house of the Parliament of the United Kingdom. Like the House of Commons, it meets in the Palace of Westminster....

. During the following year (1664), an act was passed by both Houses of Parliament to make the River Mole navigable from Reigate to the River Thames, but was never executed. The only Surrey
Surrey
Surrey is a county in the South East of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire and Berkshire. The historic county town is Guildford. Surrey County Council sits at Kingston upon Thames, although this has been part of...

 river to have been made fully navigable is the River Wey
River Wey
The River Wey in Surrey, Hampshire and West Sussex is a tributary of the River Thames with two separate branches which join at Tilford. The source of the north branch is at Alton, Hampshire and of the south branch at both Blackdown south of Haslemere, and also close to Gibbet Hill, near Hindhead...

.

In 1798 William Marshall advocated the canalisation of a short stretch of the River Mole between Betchworth
Betchworth
Betchworth is a village and civil parish in the Mole Valley district of Surrey, England. The village lies on the north bank of the River Mole, off the A25 road, about three miles east of Dorking and three miles west of Reigate. The village lay within the Reigate hundred.It was home to the now...

 and Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

 to facilitate the movement of chalk from quarry to market. In 1810 the engineer John Rennie proposed a canal linking the River Medway
River Medway
The River Medway, which is almost entirely in Kent, England, flows for from just inside the West Sussex border to the point where it enters the Thames Estuary....

 to Portsmouth
Portsmouth
Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...

 which was to have a branch to London following the Mole for much of its length. Between 1825 and 1828 the architect and civil engineer Nicholas Wilcox Cundy proposed a Grand Imperial Ship Canal from Deptford
Deptford
Deptford is a district of south London, England, located on the south bank of the River Thames. It is named after a ford of the River Ravensbourne, and from the mid 16th century to the late 19th was home to Deptford Dockyard, the first of the Royal Navy Dockyards.Deptford and the docks are...

 to Chichester
Chichester
Chichester is a cathedral city in West Sussex, within the historic County of Sussex, South-East England. It has a long history as a settlement; its Roman past and its subsequent importance in Anglo-Saxon times are only its beginnings...

 passing through the Mole Gap, however he was unable to attract sufficient financial interest in his scheme.

Today the Mole is navigable for the 400 m from the confluence with the River Thames
River Thames
The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 to Molember Weir at East Molesey
East Molesey
Molesey is a town in the Borough of Elmbridge in Surrey, England. Situated on the outskirts of Greater London, approximately from Charing Cross, it is a typical suburban area. There are two distinct areas in the town: West and East Molesey...

 where there is a private mooring facility. During the close fishing season
Coarse fishing
Coarse fishing is a term used in the United Kingdom and Ireland for angling for coarse fish, which are those types of freshwater fish other than game fish . The sport and the techniques used are particularly popular in the United Kingdom and mainland Europe.-History:The term "coarse fishing"...

 the river may be paddled by canoe
Canoe
A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...

 between Brockham
Brockham
Brockham is a village in the Mole Valley district of Surrey, England. 'Broc-ham' is so called from the Anglo Saxon meaning 'river meadow by the brook' and is first recorded in 1241. It is often mistakenly believed that there is an association with badgers but this is a modern affectation from the...

 and Fetcham
Fetcham
Fetcham is a village in Surrey, England. It is west of Leatherhead, on the other side of the River Mole and Mill Pond springs and the associated nature reserve....

 with an appropriate license from the British Canoe Union
British Canoe Union
The British Canoe Union is a national governing body for canoeing in the United Kingdom, whose stated purpose is "Helping and Inspiring people to go canoeing”....

.

World War II defences

During the Second World War several sites along the course of the Mole were fortified to facilitate the defence of London against invasion from the south. GHQ Line B
GHQ Line
The GHQ Line was a defence line built in the United Kingdom during World War II to contain an expected German invasion.The British Army had abandoned most of its equipment in France after the Dunkirk evacuation...

 ran along the North Downs from Farnham and Guildford, crossing the Mole Gap to the north of Dorking and following the river to Horley. Between Betchworth and Box Hill, the north bank of the River Mole was stabilised and made steeper to prevent wheeled vehicles from crossing. At Boxhill Farm, where access to the river from the north bank was required for the herd of dairy cows, a row of twelve concrete cylinders were cast as an anti-tank measure. Gun mounts were also installed to protect both Boxhill and Deepdene bridges and several pillboxes were installed. An anti-tank ditch was dug from the Stepping Stones eastwards across the fields belonging to Bradley Farm (now Denbies vineyard
Denbies Wine Estate
Denbies Wine Estate near Dorking, Surrey has the largest vineyard in England with under vines, representing over 10% of the plantings in the whole of the United Kingdom. It has a visitors' centre which attracts around 300,000 visitors a year....

).

The river crossing at Sidlow Bridge was heavily defended and a line of pill boxes was constructed on the north bank of the river. Concrete anti-tank cubes were provided on both side of the river, a short distance upstream of the bridge, as an obstacle to armoured vehicles
Armoured fighting vehicle
An armoured fighting vehicle is a combat vehicle, protected by strong armour and armed with weapons. AFVs can be wheeled or tracked....

.

Mole Gap

The North Downs Way
North Downs Way
The North Downs Way is a long-distance path in southern England, opened in 1978. It runs from Farnham to Dover, past Godalming, Guildford, Dorking, Merstham, Otford and Rochester, along the Surrey Hills Area of Outstanding Natural Beauty and Kent Downs AONB.East of Boughton Lees, the path splits...

 crosses the river at Box Hill
Box Hill, Surrey
Box Hill is a summit of the North Downs in Surrey, approximately south west of London. The hill takes its name from the ancient box woodland found on the steepest west-facing chalk slopes overlooking the River Mole. The western part of the hill is owned and managed by the National Trust, whilst...

 via seventeen hexagonal stepping stone
Step-stone bridge
A Step-stone bridge is a simple bridging allowing a pedestrian to cross a natural watercourse or pond, or a garden's water feature where water is allowed to course between stone steps. Unlike other bridges it has no spans. Step-stone bridges, along with log bridges are likely to be the oldest...

s, which are frequently submerged after heavy rainfall. The current stones were dedicated in September 1946 by the then Prime Minister Clement Attlee
Clement Attlee
Clement Richard Attlee, 1st Earl Attlee, KG, OM, CH, PC, FRS was a British Labour politician who served as the Prime Minister of the United Kingdom from 1945 to 1951, and as the Leader of the Labour Party from 1935 to 1955...

, replacing those destroyed during WW2 as an anti-invasion measure. The location is popular both with anglers and families, although swimming is strongly discouraged as the water is polluted in places. The stones give their name to the pub in the nearby village of Westhumble
Westhumble
Westhumble is a village situated north of Dorking in Surrey, England. Neighbouring villages include Mickleham and Great Bookham. The census area Mickleham, Westhumble and Pixham has a population of 1,932....

.

When the Burford Bridge was rebuilt in 1937, excavations revealed a "flint-surfaced approach to [a] ford at low level having all the signs of Roman workmanship" suggesting that Stane Street (which ran from London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 to Chichester
Chichester
Chichester is a cathedral city in West Sussex, within the historic County of Sussex, South-East England. It has a long history as a settlement; its Roman past and its subsequent importance in Anglo-Saxon times are only its beginnings...

 via Dorking
Dorking
Dorking is a historic market town at the foot of the North Downs approximately south of London, in Surrey, England.- History and development :...

) crossed the river at this point. In Defoe's time, there was a footbridge at this point, but carts and waggons had to cross the river by a ford.

Leatherhead

There are three listed bridges in Leatherhead of which the 14 arch Leatherhead Town Bridge is the oldest. The first bridge on this site was probably constructed during the late Middle Ages and was rebuilt and enlarged by the county surveyor George Gwilt
George Gwilt
George Gwilt , also sometimes known as George Gwilt the Elder, was an English architect of the late 18th and early 19th century, particularly associated with buildings in and around London....

 in 1782-83. The bridge is a long structure of 14 segmental arches resting on low piers, finished in red brick in Flemish bond, with some Portland stone
Portland stone
Portland stone is a limestone from the Tithonian stage of the Jurassic period quarried on the Isle of Portland, Dorset. The quarries consist of beds of white-grey limestone separated by chert beds. It has been used extensively as a building stone throughout the British Isles, notably in major...

 dressing.

A few metres downstream of Leatherhead Bridge stands the Grade II listed railway viaduct which carries the Leatherhead to Dorking line over the river. The bridge was constructed in 1867 and, at the insistence of Thomas Grissell
Thomas Grissell
Thomas Grissell was an English public works contractor who was responsible for constructing a number of prestigious buildings in England.-Early life and education:...

 the landowner, was given lavish architectural treatment.

The single span Shell Bridge stands in the grounds of Thorncroft Manor, to the south of the Town Centre. The bridge was constructed as an ornamental feature in parkland laid out by Capability Brown
Capability Brown
Lancelot Brown , more commonly known as Capability Brown, was an English landscape architect. He is remembered as "the last of the great English eighteenth-century artists to be accorded his due", and "England's greatest gardener". He designed over 170 parks, many of which still endure...

 in the late 18th century. The bridge is largely composed of flint and has a large inverted scallop shell in the place of the keystone
Keystone (architecture)
A keystone is the wedge-shaped stone piece at the apex of a masonry vault or arch, which is the final piece placed during construction and locks all the stones into position, allowing the arch to bear weight. This makes a keystone very important structurally...

 and similar shells in the spandrels at each side. The bridge was renovated and strengthened in 1999 by a group of Canadian engineers working on the Terra Nove project. The restoration project was dedicated to the memory of the Canadian servicemen, who were billeted in the Manor during the second world war.

Cobham

A wooden bridge is thought to have existed on the site of Cobham Bridge since the twelfth century, the upkeep of which was the responsibility of the adjacent landowners. The present bridge was constructed by George Gwilt
George Gwilt
George Gwilt , also sometimes known as George Gwilt the Elder, was an English architect of the late 18th and early 19th century, particularly associated with buildings in and around London....

 in 1792, after responsibility for maintenance had been transferred to the County Council by Act of Parliament. The bridge has nine low arches and is primarily built of red brick with stone coping. The parapets were rebuilt in 1914 and the structure was given a Grade II listing in 1953.

Upper Mole

Horley Mill was first mentioned in a deed of the early thirteenth century. The most recent mill was demolished in 1959, although the mill house still stands.

The first mill at Sidlow
Sidlow
Sidlow is a village in the parish of Salfords and Sidlow in the borough of Reigate and Banstead. It has a pub called the . The village also houses the Sidlow Bridge Centre which is a pupil referral unit.-External links:*...

 was built during Saxon times
History of Anglo-Saxon England
Anglo-Saxon England refers to the period of the history of that part of Britain, that became known as England, lasting from the end of Roman occupation and establishment of Anglo-Saxon kingdoms in the 5th century until the Norman conquest of England in 1066 by William the Conqueror...

. The final mill on the site was demolished in 1790, however remains of the mill leat
Leat
A leat is the name, common in the south and west of England and in Wales, for an artificial watercourse or aqueduct dug into the ground, especially one supplying water to a watermill or its mill pond...

 are still visible.

Mention is made of a mill at Brockham
Brockham
Brockham is a village in the Mole Valley district of Surrey, England. 'Broc-ham' is so called from the Anglo Saxon meaning 'river meadow by the brook' and is first recorded in 1241. It is often mistakenly believed that there is an association with badgers but this is a modern affectation from the...

 in 1634 and remains of the mill race are still visible.

Lower Mole

Slyfield Mill near Stoke d'Abernon
Stoke d'Abernon
Stoke d'Abernon is a small village situated between Cobham and Leatherhead in the county of Surrey. The census area Oxshott and Stoke d'Abernon has a population of 6,100.-History:...

 is first mentioned in Domesday Book
Domesday Book
Domesday Book , now held at The National Archives, Kew, Richmond upon Thames in South West London, is the record of the great survey of much of England and parts of Wales completed in 1086...

. It was used for fulling
Fulling
Fulling or tucking or walking is a step in woolen clothmaking which involves the cleansing of cloth to eliminate oils, dirt, and other impurities, and making it thicker. The worker who does the job is a fuller, tucker, or walker...

 woollen cloth and milling corn.

Five of the mills mentioned in Domesday Book
Domesday Book
Domesday Book , now held at The National Archives, Kew, Richmond upon Thames in South West London, is the record of the great survey of much of England and parts of Wales completed in 1086...

 were in the borough of Elmbridge.

Downside Mill, Cobham
Cobham, Surrey
Cobham is a town in the Borough of Elmbridge in Surrey, England, about south-west of central London and north of Leatherhead. Elmbridge has been acclaimed by the Daily Mail as the best place to live in the UK, and Cobham is a prosperous part of the London commuter belt...

 was the mill of the manor of Downe. Until the Dissolution of the Monasteries
Dissolution of the Monasteries
The Dissolution of the Monasteries, sometimes referred to as the Suppression of the Monasteries, was the set of administrative and legal processes between 1536 and 1541 by which Henry VIII disbanded monasteries, priories, convents and friaries in England, Wales and Ireland; appropriated their...

 it was owned by Chertsey Abbey
Chertsey Abbey
Chertsey Abbey, dedicated to St Peter, was a Benedictine monastery located at Chertsey in the English county of Surrey.It was founded by Saint Erkenwald, later Bishop of London, in 666 AD and he became the first abbot. In the 9th century it was sacked by the Danes and refounded from Abingdon Abbey...

. It has been used for many purposes including the processing of corn, paper, iron, tinplate and flock and the generation of electricity. The present building dates from the 18th century but it is inaccessible to the public.

Cobham Mill, downstream of Leatherhead, consisted of two mills used for grinding corn. In 1953 the larger mill was demolished by Surrey County Council to allieviate traffic congestion on Mill Road. The remaining red brick mill dates from the 1822 and was in use until 1928. It was restored to full working order by the Cobham Mill Preservation Trust, and is now open to the public from 2 pm to 5 pm on the second Sunday of each month (between April and October).

Esher Mill was at the end of Lower Green Road where there is now an industrial estate. It was used to process corn, brass wire, iron, paper, linoleum, and books. For many years there may have been two mills on the site for corn grinding and industrial use. There were a series of fires over a century and after the last in 1978 the buildings were demolished.

East Molesey Upper Mill was associated with the manor of Molesey Matham. It was used to produce gunpowder from the time of the Commonwealth until about 1780. The island where it stood now forms part of the ornamental gardens of a housing development called "The Wilderness".

East Molesey Lower Mill, also known as Sterte Mill, was associated with the manor of Molesey Prior. During the Commonwealth it was used for gunpowder manufacture, but after the restoration of the monarchy in 1660 it reverted to corn milling. An old timber structure was replaced by a brick building in the 1820s which can be seen from the bridge over the Ember in Hampton Court Way.

In addition there was Ember Mill, which stood on the banks of the old course of the River Ember near Hampton Court Way.

River Ember Flood Relief Channel and confluence with the Thames

The River Mole originally flowed into the River Thames at the point where the present Hampton Court bridge now crosses the Thames (approximately 500 m upstream of the present confluence
Confluence
Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...

, on the reach above Teddington Lock
Teddington Lock
Teddington Lock is a complex of three locks and a weir on the River Thames in England at Ham in the western suburbs of London. The lock is on the southern Surrey side of the river....

).

However, during the early 1930s, when Hampton Court Way and the bridge were built, the River Mole was redirected to flow into the River Ember
River Ember
The River Ember is a river in the county of Surrey, England. It is a distributary of the River Mole which splits in two at the Island Barn Reservoir to the South of East and West Molesey. The larger portion becomes the River Ember and flows in an easterly and then northerly direction around the...

 and both rivers now enter the Thames in a single widened and straightened channel once occupied only by the River Ember
River Ember
The River Ember is a river in the county of Surrey, England. It is a distributary of the River Mole which splits in two at the Island Barn Reservoir to the South of East and West Molesey. The larger portion becomes the River Ember and flows in an easterly and then northerly direction around the...

. There have been further alterations to the courses of these two rivers in a major flood prevention scheme since serious flooding in the area in 1947
1947 Thames flood
The 1947 Thames flood was worst overall 20th century flood of the River Thames, affecting much of the Thames Valley as well as elsewhere in England during the middle of March 1947 after a severe winter....

 and 1968
Great Flood of 1968
The Great Flood of 1968 was a flood caused by very heavy rain that struck South East England and France in mid-September 1968, with the worst on Sunday 15 September 1968, and followed earlier floods in South West England during July.-South West England:...

.

Photograph of the River Ember Flood Relief Channel under construction in 1981.

Literature

In The Faerie Queene
The Faerie Queene
The Faerie Queene is an incomplete English epic poem by Edmund Spenser. The first half was published in 1590, and a second installment was published in 1596. The Faerie Queene is notable for its form: it was the first work written in Spenserian stanza and is one of the longest poems in the English...

(first published in 1590) Edmund Spenser
Edmund Spenser
Edmund Spenser was an English poet best known for The Faerie Queene, an epic poem and fantastical allegory celebrating the Tudor dynasty and Elizabeth I. He is recognised as one of the premier craftsmen of Modern English verse in its infancy, and one of the greatest poets in the English...

 wrote of the river:
And Mole, that like a nousling mole doth make
His way still under ground till Thamis he overtake.



In Poly-Olbion (first published in 1612) the poet Michael Drayton
Michael Drayton
Michael Drayton was an English poet who came to prominence in the Elizabethan era.-Early life:He was born at Hartshill, near Nuneaton, Warwickshire, England. Almost nothing is known about his early life, beyond the fact that in 1580 he was in the service of Thomas Goodere of Collingham,...

 described the journey taken by the River Thames to the sea:
As still his goodly traine yet every houre increast,
And from the Surrian shores cleer Wey came down to meet
His Greatnes, whom the Tames so gratiously doth greet
That with the Fearne-crown'd Flood he Minion-like doth play:
Yet is not this the Brook, entiseth him to stay.
But as they thus, in pompe, came sporting on the shole,
Gainst Hampton-Court he meets the soft and gentle Mole.
Whose eyes so pierc't his breast, that seeming to foreslowe
The way which he so long intended was to go,
With trifling up and down, he wandreth here and there;
And that he in her sight, transparent might appeare,
Applyes himselfe to Fords, and setteth his delight,
On that which might make him gratious in her sight.

But Tames would hardly on: oft turning back to show,
For his much loved Mole how loth he was to go.
The mother of the Mole, old Holmsdale, likewise beares
Th'affection of her childe, as ill as they do theirs:
But Mole respects her words, as vaine and idle dreames,
Compar'd with that high joy, to be belov'd of Tames:
And head-long holds her course, his company to win.
Mole digs her selfe a path, by working day and night
And underneath the Earth, for three miles space doth creep:
Till gotten out of sight, quite from her mothers keep,
Her foreintended course the wanton Nymph doth run;
As longing to imbrace old Tame and Isis son...


He writes in the appendix to Song XVII

This Mole runnes into the earth, about a mile from Darking in Surrey, and after some two miles sees the light againe, which to be certaine hath been affirmed by Inhabitants thereabout reporting triall made of it.


John Milton
John Milton
John Milton was an English poet, polemicist, a scholarly man of letters, and a civil servant for the Commonwealth of England under Oliver Cromwell...

 (c. 1562–1647) described the river as
sullen Mole that runneth underneath



In a similar vein, Alexander Pope
Alexander Pope
Alexander Pope was an 18th-century English poet, best known for his satirical verse and for his translation of Homer. He is the third-most frequently quoted writer in The Oxford Dictionary of Quotations, after Shakespeare and Tennyson...

 (1688–1744) wrote in his poem Windsor Forest (first published 1713)
And sullen Mole that hides his diving flood



Robert Bloomfield
Robert Bloomfield
Robert Bloomfield was an English labouring class poet whose work is appreciated in the context of other self-educated writers such as Stephen Duck, Mary Collier and John Clare.-Life:...

 (1766–1823) writes the following lines about the Mole Valley in his 1806 poem Wild Flowers.
Sweet Health, I seek thee! Hither bring
Thy balm that softens human ills;
Come on the long drawn clouds that fling
Their shadows o'er the Surry-Hills.
Yon green-topt hills, and far away
Where late as now I freedom stole,
And spent one dear delicious day
On thy wild banks romantic Mole.

Ay there's the scene! Beyond the sweep
Of London's congregated cloud,
The dark-brow'd wood, the headlong steep,
And valley paths without a crowd!
Here Thames I watch thy flowing tides,
Thy thousand sails am proud to see;
But where the Mole all silent glides
Dwells Peace - and Peace is wealth to me.



Extract from The River Mole or Emlyn Stream by Mary Uniacke (writing under her maiden name Mary Drinkwater-Bethune), which was published in 1839.
Who may count back that forgotten time
When first the waters forced an outlet here:
When the foundations of these stedfast hills
Were shaken, and the long imprisoned stream
Flowed through the yawning chasm? That awful day
Yet leaves its trace. The waters find their way,
Now laughing in the sun - now swallowed up
In caverns pervious to their course alone,
They leave their channel dry, and hide awhile
Their silent flow; like bitter tears, unshed
From the dim eye, before a careless world
Unheeding of our grief; but swelling still
In the full heart, which leaves unsoothed, unseen,
And broods o'er ruined hopes, and days gone by.


Tributaries

The major tributaries of the River Mole are the Isfield Brook, Gatwick Stream
Gatwick Stream
The Gatwick Stream is a tributary of the River Mole in southern England. The Gatwick Stream rises in Worth Forest in West Sussex and flows northwards through Tinsley Green to meet the Mole on the border between West Sussex and Surrey...

, Earlswood Brook, Pipp Brook and The Rye
The Rye (Brook)
The Rye is a stream rising east of Ashtead and flowing into the River Mole near Leatherhead, Surrey.The Rye Brook flows westwards across Ashtead Common, through the Ashtead Common National Nature Reserve, managed by the City of London Corporation...

. A full list of the tributaries is given in the table below.

See also

  • List of rivers in England
  • Tributaries of the River Thames
    Tributaries of the River Thames
    This article lists the tributaries of the River Thames, in England. It also includes significant backwaters and waterways which also have confluences with the main stream of the River Thames.Most of the tributaries are natural, but a few were man-made...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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