120 COLE : PHYSICAL GEOGRArHY OF THE EAST RIDING. 
by sinking- a well to a depth of 300ft. Of course the Vale of 
Pickering- is a mass of Kimeridg-e Clay 400 to 500ft. deep, but as 
this is covered up with alluvial deposits, it suffices to mention the 
fact. 
The Speeton Clay, which is a marine formation equivalent to 
the fresh-water deposits of the Wealden in the South of England, 
occupies a corner in the extreme north-east of the East-Riding. Here 
a fairly large portion, half-a-mile in length, is available for investiga- 
tion, and so well has it been studied by Professor Judd, that three 
distinct zones have been mapped, each containing characteristic 
fossils. Strips of this clay appear along the northern edge of the 
Wolds from Ganton to Knapton. In Painsthorpe Dale, near Kirby 
Underdale, there is another exposure of Neocomian age, but in this 
case the rock is a coarse irony sandstone. 
In the south, beds of the horizon just mentioned are followed 
by Gault and Upper Greensand, but in the north they are absent. 
The rock which immediately rests on Speeton Clay is Red Chalk. 
This appears to underlie the whole Chalk area of Yorkshire and 
Lincolnshire. Wherever the Red Chalk appears on the sides of the 
hills there are the springs. This is noticeable as the line of 
moisture is an important factor in botanical or conchological research. 
Grey Chalk succeeds, and is partially intermixed with the Red 
Chalk, and both are followed by a thin band of Black Chalk, with 
vegetable and animal remains, which forms a boundary line between 
these somewhat argillaceous bands and the flint-bearing White 
Chalk. The greater portion of the surface of the Wolds is composed 
of this middle flint-bearing chalk. All round the northern and 
western edge the flints lie on the ground in such profusion, that it 
is a matter of wonder how a blade of corn can pierce its way 
upwards. In many cases the flints are gathered up by hand, but 
the supply is almost inexhaustible, and the benefit doubtful when 
done. 
There is a narrow district extending from Flamborough Head 
through Burton Agnes and Cottam to Wetwang, thence south to 
Beverle}^, where the Upper beds of the Chalk appear. These 
contain no flints, but there is a larger proportion of Silica in the 
