In going through my papers found an article (from 1990s?) ‘From dolines to dewponds’ by Colin Hayfield and Pat Wagner. A doline is a depression in the land surface resulting from the collapse of an underground hollow in the porous bedrock (chalk). Dewponds are man-made, clay-lined shallow surface depressions in which dew condenses to provide a source of water, usually for farm animals to drink.
The study concentrates on the north-west part of the High Yorkshire Wolds and includes parishes such as Wharram Percy, Thixendale, Fimber and Towthorpe.
The article is sub-titled ‘a study of water supplies on the Yorkshire Wolds’. In progressing this study the authors provide a brief history of the landscape history of the Yorkshire Wolds which is very useful.
The dolines clearly have to have some impermeable lining to function in the same way as dewponds. As the Ice sheets of the last ice age (Devensian) did not over-top the high Wolds (as also on the Lincolnshire Wolds) it is thought that some water holding dolines may date from the previous ice age (Anglian). On an area with porous base rock sources of water would be more critical in defining sites of pre-historic settlement than elsewhere. With historic water table levels likely to have been much higher than today another source of water would have been valley bottoms then fed by springs, now dry. The course of the Gypsey Race along the Great Wold Valley and flowing into the Bay at Bridlington is still usually surface water and parish boundaries along its course were drawn to incorporate sections of valley bottom, valley side and high wold in each parish.
It is thought that modern arable agriculture has destroyed the ecology of many dolines whereas in some parishes they have become ‘village ponds’ e.g. in Fimber and Fridaythorpe.
Part 2 next time.