Geology of Cheshire
Encyclopedia
The geology of Cheshire in England
consists mainly of Triassic
sandstone
s and mudstone
s. To the north west of Cheshire
, these rocks are heavily faulted and the underlying Carboniferous
Coal Measures
are thrown up. Around the areas of Poynton
and Macclesfield
, the coal is close to the surface and was easily mined. Below the Coal Measures is the Millstone Grit
, which appears towards the Derbyshire
border on the flanks of the Peak District
dome
.
The Cheshire Basin
is a major sedimentary basin
which comprises the larger part of the county. This fault-bounded half-graben
structure is bounded to the east and southeast by a series of faults of which the most significant is the Red Rock Fault. Numerous faults trend north-south through the basin, some of which help to define the series of hills which are known collectively as the Mid Cheshire Ridge
. The basin was flooded on several occasions in the Permian
and early Triassic periods resulting in the laying down of massive halite
(salt) beds. These beds have been mined both by cavern working and hot water brine
extraction for over 200 years, mainly in the area around Northwich
. The collapse of some of these worked-out halite beds has given rise to some of Cheshire's noted features, the Cheshire Meres.
period are largely restricted to that part of the county to the east of the Red Rock Fault. They comprise mudstones, siltstones and sandstones of the Lower Coal Measures
and of the Millstone Grit
Group. A very small outcrop of Carboniferous Limestone
formerly occurred near Astbury
though this has largely been removed by quarrying.
Coal Measures strata also occurs in the Neston area though it is obscured by glacial till and estuarine alluvium. It represents the easternmost extent of the Flintshire Coalfield
. An inlier of upper Carboniferous rocks occurs to the south of Chester though it too is obscured by superficial deposits.
Carboniferous strata underlies the entire Cheshire basin at depth.
and Triassic
periods. Both the east and west Cheshire Plain
s are immediately underlain by Triassic sandstones, siltstones and mudstones though outcrops are restricted to those areas which are not covered by thick expanses of glacial till of glacio-fluvial sands and gravels, such as the Mid Cheshire Ridge
and Alderley Edge
.
Rocks of Permian age are encountered to the west of Chester and in restricted areas to the southeast and northeast of the city, though again largely obscured by superficial deposits.
age. Outcrops are very scarce as the thick cover of glacial till in this area largely obscures the underlying bedrock. The strata are assigned to the lowermost Jurassic Lias Group
comprising mudstones and limestones.
is covered by a thick mantle of glacial till and sands and gravels of glacio-fluvial origin. These deposits are the legacy of the over-riding of the area on several occasions by glacial ice during the past 2 million years. The present distribution of deposits and the landforms to which they give rise are largely the result of the last ice age
, the Devensian which peaked around 22-20,000 years ago. Kettle holes caused by the in-situ melting of ice-blocks during deglaciation are a notable feature of the landscape. Many are now dry though others such as Hatchmere
and Pettypool remain as locally significant waterbodies.
The morphology of both the Dee and Mersey estuaries is in large part owed to the passage of Irish Sea Ice southwestwards over the relatively soft sandstones of the area. These features have been termed iceway
s. There are also a number of tunnel valleys
beneath modern river valleys and other parts of the plain, excavated by ice and meltwater. Striking examples underlie the lower and middle stretches of the Weaver
valley and those of the Dee
and Gowy
near Chester
.
A considerable number of small glacial meltwater channels
have been identified along the Mid Cheshire Ridge
such as that known as Urchin's Kitchen near Kelsall
whilst larger examples occur along the edges of the Peak District
. There are notable examples at Lyme Park
and southwards to Bollington
and again in the Bosley
area, south of Macclesfield
.
The floodplains of the majority of watercourses in the county are composed of alluvium
which has accumulated in the post-glacial period. River terraces can be identified along some valleys such as those of the River Mersey
and River Dane
, reflecting changing base levels to which these rivers have been cutting down.
Peat deposits have accumulated in various of the kettle-holes, not least within Delamere Forest
, and on parts of the high ground of the east of the county where thin soils and high rainfall have contributed to their formation.
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
consists mainly of Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s and mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
s. To the north west of Cheshire
Cheshire
Cheshire is a ceremonial county in North West England. Cheshire's county town is the city of Chester, although its largest town is Warrington. Other major towns include Widnes, Congleton, Crewe, Ellesmere Port, Runcorn, Macclesfield, Winsford, Northwich, and Wilmslow...
, these rocks are heavily faulted and the underlying Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
are thrown up. Around the areas of Poynton
Poynton
Poynton is a town within the civil parish of Poynton-with-Worth, and the unitary authority area of Cheshire East, England. For ceremonial purposes it is part of the county of Cheshire. Poynton is located at the eastern most fringe of the Cheshire Plain, north of Macclesfield, south of Stockport...
and Macclesfield
Macclesfield
Macclesfield is a market town within the unitary authority of Cheshire East, the county palatine of Chester, also known as the ceremonial county of Cheshire, England. The population of the Macclesfield urban sub-area at the time of the 2001 census was 50,688...
, the coal is close to the surface and was easily mined. Below the Coal Measures is the Millstone Grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
, which appears towards the Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...
border on the flanks of the Peak District
Peak District
The Peak District is an upland area in central and northern England, lying mainly in northern Derbyshire, but also covering parts of Cheshire, Greater Manchester, Staffordshire, and South and West Yorkshire....
dome
Dome (geology)
In structural geology, a dome is a deformational feature consisting of symmetrically-dipping anticlines; their general outline on a geologic map is circular or oval...
.
The Cheshire Basin
Cheshire Basin
The Cheshire Basin is a late Palaeozoic and Mesozoic sedimentary basin which extends under most of the county of Cheshire in northwest England. It extends northwards into the Manchester area and south into Shropshire...
is a major sedimentary basin
Sedimentary basin
The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification...
which comprises the larger part of the county. This fault-bounded half-graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
structure is bounded to the east and southeast by a series of faults of which the most significant is the Red Rock Fault. Numerous faults trend north-south through the basin, some of which help to define the series of hills which are known collectively as the Mid Cheshire Ridge
Mid Cheshire Ridge
The Mid Cheshire Ridge is a range of low sandstone hills which stretch north to south through Cheshire in North West England. The ridge is discontinuous, with the hills forming two main blocks, north and south of the "Beeston Gap"...
. The basin was flooded on several occasions in the Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
and early Triassic periods resulting in the laying down of massive halite
Halite
Halite , commonly known as rock salt, is the mineral form of sodium chloride . Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities...
(salt) beds. These beds have been mined both by cavern working and hot water brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
extraction for over 200 years, mainly in the area around Northwich
Northwich
Northwich is a town and civil parish in the unitary authority of Cheshire West and Chester and the ceremonial county of Cheshire, England. It lies in the heart of the Cheshire Plain, at the confluence of the rivers Weaver and Dane...
. The collapse of some of these worked-out halite beds has given rise to some of Cheshire's noted features, the Cheshire Meres.
Carboniferous
Rocks originating in the CarboniferousCarboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
period are largely restricted to that part of the county to the east of the Red Rock Fault. They comprise mudstones, siltstones and sandstones of the Lower Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
and of the Millstone Grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
Group. A very small outcrop of Carboniferous Limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...
formerly occurred near Astbury
Newbold Astbury
thumb|AstburyNewbold Astbury is a village and civil parish in the unitary authority of Cheshire East and the ceremonial county of Cheshire, in the north-west of England. It is situated to the south of Congleton on the A34 road to Scholar Green; the A34 forms one side of the triangular village green...
though this has largely been removed by quarrying.
Coal Measures strata also occurs in the Neston area though it is obscured by glacial till and estuarine alluvium. It represents the easternmost extent of the Flintshire Coalfield
Flintshire Coalfield
The Flintshire Coalfield in north-east Wales is one of the smaller British coalfields. It extends from the Point of Ayr in the north, along the Dee Estuary through Connah's Quay to Caergwrle in the south. A small part extends onto the Wirral i.e. English coast of the estuary at Neston which was the...
. An inlier of upper Carboniferous rocks occurs to the south of Chester though it too is obscured by superficial deposits.
Carboniferous strata underlies the entire Cheshire basin at depth.
Permo-Triassic
The majority of the solid rocks of Cheshire are sedimentary rocks laid down during the PermianPermian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
and Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
periods. Both the east and west Cheshire Plain
Cheshire Plain
The Cheshire Plain is a relatively flat expanse of lowland situated almost entirely within the county of Cheshire in northwest England. It is bounded by the hills of North Wales to the west, and the Peak District of Derbyshire and North Staffordshire to the east and southeast...
s are immediately underlain by Triassic sandstones, siltstones and mudstones though outcrops are restricted to those areas which are not covered by thick expanses of glacial till of glacio-fluvial sands and gravels, such as the Mid Cheshire Ridge
Mid Cheshire Ridge
The Mid Cheshire Ridge is a range of low sandstone hills which stretch north to south through Cheshire in North West England. The ridge is discontinuous, with the hills forming two main blocks, north and south of the "Beeston Gap"...
and Alderley Edge
Alderley Edge
Alderley Edge is a village and civil parish within the unitary authority of Cheshire East and the ceremonial county of Cheshire, England. According to the 2001 census the parish had a population of 4,409....
.
Rocks of Permian age are encountered to the west of Chester and in restricted areas to the southeast and northeast of the city, though again largely obscured by superficial deposits.
Jurassic
Small areas of the extreme south of the county are underlain by rocks of JurassicJurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
age. Outcrops are very scarce as the thick cover of glacial till in this area largely obscures the underlying bedrock. The strata are assigned to the lowermost Jurassic Lias Group
Lias Group
The Lias Group or Lias is a lithostratigraphic unit found in a large area of western Europe, including the British Isles, the North Sea, the low countries and the north of Germany...
comprising mudstones and limestones.
Quaternary
The larger part of the Cheshire PlainCheshire Plain
The Cheshire Plain is a relatively flat expanse of lowland situated almost entirely within the county of Cheshire in northwest England. It is bounded by the hills of North Wales to the west, and the Peak District of Derbyshire and North Staffordshire to the east and southeast...
is covered by a thick mantle of glacial till and sands and gravels of glacio-fluvial origin. These deposits are the legacy of the over-riding of the area on several occasions by glacial ice during the past 2 million years. The present distribution of deposits and the landforms to which they give rise are largely the result of 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 Devensian which peaked around 22-20,000 years ago. Kettle holes caused by the in-situ melting of ice-blocks during deglaciation are a notable feature of the landscape. Many are now dry though others such as Hatchmere
Hatchmere
thumb|Swimmers in Hatchmerethumb|Swimmers in HatchmereHatchmere is a small lake in Cheshire, adjacent to Delamere Forest. It is also the name of a hamlet near to the village of Norley. Hatchmere is notable for several campaigns to maintain public access to the lake after it was boughtby the...
and Pettypool remain as locally significant waterbodies.
The morphology of both the Dee and Mersey estuaries is in large part owed to the passage of Irish Sea Ice southwestwards over the relatively soft sandstones of the area. These features have been termed iceway
Iceway
An iceway is a linear channel eroded through bedrock by the passage of glacial ice. The term was coined by geographer Ronald Kay Gresswell in a paper in 1964 in relation to the origins of the Dee and Mersey estuaries on the boundary of northwest England and northeast Wales...
s. There are also a number of tunnel valleys
Tunnel valley
A tunnel valley is a large, long, U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages....
beneath modern river valleys and other parts of the plain, excavated by ice and meltwater. Striking examples underlie the lower and middle stretches of the Weaver
River Weaver
The River Weaver is a river, navigable in its lower reaches, running in a curving route anti-clockwise across west Cheshire, northern England. Improvements to the river to make it navigable were authorised in 1720 and the work, which included eleven locks, was completed in 1732...
valley and those of the Dee
River Dee, Wales
The River Dee is a long river in the United Kingdom. It travels through Wales and England and also forms part of the border between the two countries....
and Gowy
River Gowy
The River Gowy is a river in Cheshire, England and a tributary of the River Mersey.It rises in western Cheshire in the hills near Peckforton Castle, very close to the source of the River Weaver. While the Weaver flows south initially, the Gowy flows north and for several miles provides the valley...
near Chester
Chester
Chester is a city in Cheshire, England. Lying on the River Dee, close to the border with Wales, it is home to 77,040 inhabitants, and is the largest and most populous settlement of the wider unitary authority area of Cheshire West and Chester, which had a population of 328,100 according to the...
.
A considerable number of small glacial meltwater channels
Subglacial channel
A subglacial meltwater channel is a channel beneath an ice mass, like ice sheets and valley glaciers, roughly parallel to the main ice direction. These meltwater channels can have different sizes, ranging from very small channels of a metre deep and wide to big valleys which can be up to a...
have been identified along the Mid Cheshire Ridge
Mid Cheshire Ridge
The Mid Cheshire Ridge is a range of low sandstone hills which stretch north to south through Cheshire in North West England. The ridge is discontinuous, with the hills forming two main blocks, north and south of the "Beeston Gap"...
such as that known as Urchin's Kitchen near Kelsall
Kelsall
Kelsall is a medium-sized agricultural/commuter village and civil parish in the unitary authority of Cheshire West and Chester and the ceremonial county of Cheshire, England. It is located around east of Chester, west of Northwich and north west of Tarporley...
whilst larger examples occur along the edges of the Peak District
Peak District
The Peak District is an upland area in central and northern England, lying mainly in northern Derbyshire, but also covering parts of Cheshire, Greater Manchester, Staffordshire, and South and West Yorkshire....
. There are notable examples at Lyme Park
Lyme Park
Lyme Park is a large estate located south of Disley, Cheshire, England. It consists of a mansion house surrounded by formal gardens, in a deer park in the Peak District National Park...
and southwards to Bollington
Bollington
Bollington is a small rural town and civil parish in the county of Cheshire, , England, in the unitary authority of Cheshire East. It is located east of Prestbury. In the Middle Ages it was part of the Earl of Chester's manor of Macclesfield., and the ancient parish of Prestbury...
and again in the Bosley
Bosley
Bosley is a village and civil parish in the unitary authority of Cheshire East and the ceremonial county of Cheshire, England. According to the 2001 census it had a population of 406. The village is on the A523 road about six miles south of Macclesfield...
area, south of Macclesfield
Macclesfield
Macclesfield is a market town within the unitary authority of Cheshire East, the county palatine of Chester, also known as the ceremonial county of Cheshire, England. The population of the Macclesfield urban sub-area at the time of the 2001 census was 50,688...
.
The floodplains of the majority of watercourses in the county are composed of alluvium
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
which has accumulated in the post-glacial period. River terraces can be identified along some valleys such as those of the River Mersey
River Mersey
The River Mersey is a river in North West England. It is around long, stretching from Stockport, Greater Manchester, and ending at Liverpool Bay, Merseyside. For centuries, it formed part of the ancient county divide between Lancashire and Cheshire....
and River Dane
River Dane
The River Dane is a river mainly in Cheshire in the north west of England.The river rises in Derbyshire, close to the source of the River Goyt just to the south west of Buxton, on Axe Edge Moor...
, reflecting changing base levels to which these rivers have been cutting down.
Peat deposits have accumulated in various of the kettle-holes, not least within Delamere Forest
Delamere Forest
Delamere Forest or Delamere Forest Park is a wood in the Cheshire West and Chester area of Cheshire, England, near the town of Frodsham. It includes of mixed deciduous and evergreen woodland, centred at around , making it the largest area of woodland in Cheshire...
, and on parts of the high ground of the east of the county where thin soils and high rainfall have contributed to their formation.
See also
- Geology of the United Kingdom
- Geology of EnglandGeology of EnglandThe Geology of England is mainly sedimentary. The youngest rocks are in the south east around London, progressing in age in a north westerly direction. The Tees-Exe line marks the division between younger, softer and low-lying rocks in the south east and older, harder, and generally a higher relief...
- List of geology of English counties
- Geology of ShropshireGeology of ShropshireShropshire's Geology is very diverse and most rock types found in the British Isles can be found in the county too. There is also a large amount of mineral wealth, including lead, coal and iron in the county, which perhaps helped the area develop the first industry of the industrial revolution, in...
- Geology of Alderley EdgeGeology of Alderley EdgeAlderley Edge in Cheshire is one of the classic locations for the study of Triassic sandstones in the United Kingdom. Numerous scientists from the early 19th century up to the present day have studied the area and it is a popular field site for universities around the UK. As time progresses, new...