COLE : PHYSICAL GEOGRAPHY OF THE EAST RIDING. 115 
and wet seasons. The main dip of the Chalk is towards the south-east; 
hence the greater portion of the rain which falls over an area 
estimated at 420 sq. miles finds its way to Holderness, but there it 
meets an impervious sheet of Boulder Clay, lying on the surface of 
the Chalk, through which it cannot possibly rise except by means of 
Artesian Wells. Consequently, when the Chalk strata below are 
fully charged with water, springs burst out at the edge of the 
Boulder Clay which are mostly perennial. Sometimes, as at 
Kirkburn, they cease altogether during a dry season, whilst at other 
times, during a wet season, they accumulate such force as to burst 
through a solid highroad. These peculiar outbursts of water are 
known by the name of " Gypseys," and the flow of water is called 
the " Gypsey-race," another peculiarity of the East-Riding. 
At the northern and western sides of the Wolds there is a 
copious discharge of water from the innumerable springs, which 
burst forth at the junction of the Chalk with the underl3^ing clays, 
whether Kimeridge or Lias. This line of junction occurs at varying 
heights, but attains its maximum above sea level at the north-west 
corner of the Wolds, at an elevation of about 500 feet. Hence the 
mass of the Chalk Wolds, east and south of this point, is shown to 
be composed not of Chalk, but of earlier rocks thrown up millions of 
years ago, in an anticlinal stretching probably through Harrogate 
from Lancashire, and subsequently denuded before the area in 
question formed the bottom of a Cretaceous sea. 
There are but two rivers woi thy of the name, and even that is 
saying a great deal, namely, the Derwent and the Hull. The former 
rises in the heart of the Moorlands to the north and, having cut 
through the gorge of the Forge Valley, is joined in its progress 
through the Vale of Pickering b}' a number of streams coming down 
from Newton Dale, Rosedale, Farndale, Bransdale, and Bilsdale, 
besides the becks issuing from the Chalk Wolds on the south, and 
a second time cuts through a barrier of Oolitic rocks, and finds its 
way into the Vale of York, where eventually it joins the Ouse. The 
other river, the Hull, rises somewhat promiscuously. It is difficult 
to say where its origin is^ in consequence of the " Gypseys." The 
streams which contribute to it burst out from the edge of the clay 
