A
Dew pond is an artificial
pondA pond is an inland body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar...
usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. The name dew pond (sometimes
cloud pond or
mist pond) was first recorded in south
WiltshireWiltshire is a ceremonial county in the south west of England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers 3,485 km²...
in 1879, but it was claimed to have been in use there since “time immemorial”.
They are usually shallow, saucer-shaped and lined with
puddledPuddle is a watertight material based on clay used in building and maintaining canals or reservoirs. Puddling is the process of lining the channel with puddle....
clayClay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired...
,
chalkChalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores. It is common to find flint and chert...
or
marlMarl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
on an insulating straw layer over a bottom layer of chalk or lime.
A
Dew pond is an artificial
pondA pond is an inland body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar...
usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. The name dew pond (sometimes
cloud pond or
mist pond) was first recorded in south
WiltshireWiltshire is a ceremonial county in the south west of England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers 3,485 km²...
in 1879, but it was claimed to have been in use there since “time immemorial”.
They are usually shallow, saucer-shaped and lined with
puddledPuddle is a watertight material based on clay used in building and maintaining canals or reservoirs. Puddling is the process of lining the channel with puddle....
clayClay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired...
,
chalkChalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores. It is common to find flint and chert...
or
marlMarl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
on an insulating straw layer over a bottom layer of chalk or lime. To deter earthworms from their natural tendency of burrowing upwards, which in a short while would make the clay lining porous, a layer of soot would be incorporated or lime mixed with the clay. The clay is usually covered with straw to prevent cracking by the sun and a final layer of chalk rubble or broken stone to protect the lining from the hoofs of sheep or cattle.
A method of constructing the base layer using chalk puddle was described in
The Field December 14 1907.
A Sussex farmer born in 1850 tells how he and his forefathers made dew ponds:
“The requisite hole having been excavated, the chalk was laid down layer by layer, while a team of oxen harnessed to a heavy broad-wheeled cart was drawn round and round the cup shaped hole to grind the chalk to powder. Water was then thrown over the later as work progressed, and after nearly a day of this process, the resultant mass of puddled chalk, which had been reduced to the consistency of thick cream, was smoothed out with the back of a shovel from the centre, the surface being left at last as smooth and even as a sheet of glass. A few days later, in the absence of frost or heavy rain, the chalk had become as hard as cement, and would stand for years without letting water through. This old method of making dew ponds seems to have died out when the oxen disappeared from the Sussex hills, but it is evident that the older ponds, many of which have stood for scores of years practically without repair, are still more watertight than most modern ones in which Portland cement has been employed.”
Despite the name, their primary source of water is believed to be rainfall rather than dew or mist.
History
The mystery of dew ponds has drawn the interest of many historians and scientists, but until recent times there has been little agreement on their early origins. It was widely believed that the technique for building dew ponds has been understood from the earliest times, as
KiplingRudyard Kipling was a British author and poet. Born in Bombay, British India, he is best known for his works of fiction The Jungle Book , Kim , many short stories, including The Man Who Would Be King ; and his poems, including...
tells us in
Puck of Pook's HillPuck of Pook's Hill is a historical fantasy book by Rudyard Kipling, published in 1906, containing a series of short stories set in different periods of English history. The stories are all told to two children living near Pevensey by people magically plucked out of history by elf Puck, or by Puck...
. The two
Chanctonbury HillChanctonbury Ring is a hill fort based ring of trees atop Chanctonbury Hill on the South Downs, on the border of the civil parishes of Washington and Wiston in the English county of West Sussex...
dew ponds were dated, from flint tools excavated nearby and similarity to other dated earthworks, to the
neolithic periodThe Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BCE in the Middle East that is traditionally considered the last part of the Stone Age...
.
Landscape archaeologyLandscape archaeology is a body of method and theory for the study of the material traces of past peoples within the context of their interactions in the wider social and natural environment they inhabited...
too seemed to demonstrate that they were used by the inhabitants of the nearby
hill fortA hill fort is a type of fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage. They are typically European and of the Bronze and Iron Ages...
(probably from an earlier date than that of the surviving
late bronze ageThe Bronze Age of a culture is the period when the most advanced metalworking in that culture utilised bronze. This could either have been based on the local smelting of copper and tin from ores, or trading for bronze from production areas elsewhere...
structure) for watering cattle. A more prosaic assessment from
Maud CunningtonMaud Edith Cunnington , was a Welsh-born archaeologist, most famous for her pioneering work on the prehistoric sites of Salisbury Plain....
, an archaeologist from Wiltshire, while not ruling out a prehistoric origin, describes such positive interpretations of the available evidence as no more than “flights of fancy”. A strong claim to antiquity may, however, be made for at least one Wiltshire dew pond: A
land deedA deed is a signed and usually sealed legal instrument in writing used to grant a right. Deeds have historically been part of the broader category of instruments under seal, requiring only the affixing of a common seal to render them valid. Today, however, deeds are instruments in solemn form...
dated 825
CECommon Era, abbreviated as CE, is a designation for the calendar system most commonly used world-wide for numbering the year part of the date...
mentions Oxenmere at
Milk HillMilk Hill, located near Alton Priors is the highest point in the county of Wiltshire, UK at some 295 m above sea level ....
, Wiltshire, showing that dew ponds were in use during the
SaxonAnglo-Saxons is the term usually used to describe the invading Germanic tribes in the south and east of Great Britain from the early 5th century AD, and their creation of the English nation, to the Norman conquest of 1066...
period. In the eighteenth century the naturalist
Gilbert WhiteGilbert White was a pioneering naturalist and ornithologist.White was born in his grandfather's vicarage at Selborne in Hampshire. He was educated by a private tutor in Basingstoke before going to Oriel College, Oxford...
noted that during extended periods of summer drought the artificial ponds on the
downsA downland is an area of open chalk hills. This term is especially used to describe the chalk countryside in southern England. Areas of downland are often referred to as Downs....
above his native
SelborneSelborne is a village in the East Hampshire district of Hampshire, England. It is south of Alton. It will be just within the extreme northern boundary of the proposed South Downs National Park, which is due to take effect in mid-2010....
, Hampshire, retained their water, despite supplying flocks of sheep, while larger ponds in the valley below had dried up. Later observations demonstrated that during a night of favourable dew formation a typical increase in water level of some two or three inches was possible.
There is equal controversy on the means of replenishment of dew ponds. Experiments conducted in 1885 to determine the origin of the water found that dew forms not from dampness in the air but from moisture in the ground directly beneath the site of the condensation: dew, therefore, was ruled out as a source of replenishment. Other scientists have pointed out that the 1885 experiments failed to take into account the insulating effect of the straw and the cooling effect of the damp clay: the combined effect would be to keep the pond at a lower temperature than the surrounding earth and thus able to condense a disproportionate share of moisture.
In turn these conclusions were disproved in the 1930s, when it was pointed out that the heat-retaining quality of water (its
thermal capacitySpecific heat capacity, often shortened to specific heat, is the measure of the heat energy required to increase the temperature of a of a substance by unit degree. The term originated primarily through the work of 18th-century physicist Joseph Black who conducted various heat measurements and...
) was many times greater than that of earth and therefore the air above a pond in summer would be the last place to attract condensation. The deciding factor, it was concluded, is the extent of the saucer-shaped basin extending beyond the pond itself: the large basin would deliver more rainfall than a pond created without such a surrounding feature.
Dew ponds are still common on the downlands of southern
EnglandEngland 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 and the North Sea to the east, with the English Channel to the south separating it from continental...
, the
North DerbyshireDerbyshire 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...
and
Staffordshire moorlandsStaffordshire Moorlands is a local government district in Staffordshire, England. Its council, Staffordshire Moorlands District Council, is based in Leek and is located between the city of Stoke-on-Trent and the Peak District National Park. The 2001 census recorded the population as...
and in
NottinghamshireNottinghamshire is an English county in the East Midlands, which borders South Yorkshire, Lincolnshire, Leicestershire and Derbyshire...
.
External links