Why Is There a Bare Rolling Upland With No Rivers? The Water Went Underground

Chalk and many limestones are porous and fractured, so rain falling on them soaks straight in rather than running across the surface, and it travels down until it reaches the level below which the rock is saturated. That means there is almost no surface drainage on high ground of this kind, and water emerges instead at springs where the permeable rock meets something impermeable, which is usually well down the slope or at the foot of the escarpment. The uplands are therefore dry, and settlement historically clustered at the spring line rather than on the high ground.

The combination of features is distinctive and consistent:

• •Smooth rounded hills with few sharp edges
• •A steep escarpment on one side and a gentle slope on the other
• •Deep winding valleys with no stream in them
• •Thin soil with flint or chert scattered across it
• •Few trees on the tops, historically grazed by sheep
• •Villages at the foot rather than on the hill

Valleys cut by running water in ground where water does not run are the most striking feature and the explanation involves conditions that no longer exist. During the cold phases of the ice ages the ground was permanently frozen to depth, so the porous rock could not absorb anything, and meltwater in spring ran across the surface in quantity and cut valleys exactly as it would on clay. When the ground thawed permanently, the rock resumed absorbing and the streams stopped, leaving the valleys behind with nothing flowing in them. A few flow briefly after exceptional rainfall, which is how such streams acquired local names meaning that they come and go.

The term comes from an old word meaning woodland, which is the reverse of what the landscape now looks like and records what was there before it was cleared. That origin is shared with the German word for forest and with several related terms across the Germanic languages. In England it attaches to specific regions, principally the chalk uplands of Lincolnshire and the eastern part of Yorkshire, and to limestone country in Leicestershire and Kent, and it appears in a great many settlement names across those areas. Reading a place name containing it therefore indicates both the geology underfoot and a vegetation history that has completely reversed.

The land was used in ways that follow from what it can support and that shaped the whole region. Thin dry soil suits sheep far better than arable, and enormous flocks grazed these uplands for centuries, which is where the wool that funded so many churches came from. That grazing kept the turf short and open, producing a species-rich grassland that is now rare and protected. Prehistoric monuments and trackways concentrate on these uplands, partly because the ground was open and passable when the clay lowlands were wooded and wet. Later ploughing of the tops, made possible by fertiliser and machinery, has removed most of the old grassland.

Rain soaks straight into porous chalk and limestone, so high ground of this kind carries almost no surface water and villages sit at the spring line below instead. Valleys cut into it were made when ice age permafrost stopped the rock absorbing and meltwater ran on the surface, which is why they are dry now. Thin soil suited sheep, and the wool funded the churches.