32 
cole: on the red chalk. 
highest elevation, and increases in thickness, in a line drawn 
from the north-west corner of the wolds to Hornsea in 
Holderness, where it is 800 ft. thick, at a depth of 135 ft. 
below the surface of the boulder clay. (Compare section 5.) 
The thinness of the chalk at high elevations is shown 
in the four following sections, each about 1 j miles in length. 
The first (1) is from the Cement Stone Quarry, figured 
in Messrs. Blake & Huddlestone's " Corallian Rocks," p. 375, 
to Duggleby, in a direction due east. 
The second (2) is from Wharram Percy Church to a pond 
and springs, close to Burdale Station, in a direction south by 
east. 
The third (3) from Bishop Witton to Whitekeld Dale, 
near Givendale, direction east. 
The fourth (4) from a spring on the Kilnwick Percy 
Hill, which supplies Admiral Duncombe's house, to the 
pond in Warter village, direction east. 
In the first, the grey chalk is highest at the west end, 
450 ft., and appears at 375 ft. at the east end. The white 
chalk, in the hill above called the Peak, attains a height 
of 561 ft., and is therefore only about 150 ft. thick. In the 
second, the red chalk dips from 450 ft. to 338 ft., whilst the 
summit of the intermediate hill is 675 ft. So that a thick- 
ness of nearly 300 ft. might be assigned to the white chalk, 
were it not for another fact brought to light by the boring 
of Burdale Tunnel, adjoining the line of section. This tunnel, 
one mile long, was bored almost throughout its entire length 
in Kimmeridge clay. At the south, or Burdale end, the 
railway enters the tunnel at an elevation of 400 ft., and with 
an incline of 1 in 70. This would make the elevation of 
the railway towards the centre about 440 ft., whereas the 
highest point on the surface is only 660 ft. So that, what 
with the height of the tunnel itself, wholly bored here in 
Kimmeridge clay, it may be confidently asserted that 200 ft. 
