34 
COLE : ON THE RED CHALK. 
denudation, has been raised highest by subterranean forces ; 
and that this action found its fullest development in the 
neighbourhood of the valley from North Grimston to Whar- 
ram and Bur dale Tunnel, which valley is probably due to 
a crack or fissure, produced by upheaval and tension of the 
superincumbent beds. Denudation has worn down the sides, 
but not equally. On the east side of the valley, the grey 
chalk appears at an almost uniform level of 400 ft. ; whereas 
on the west side it attains a height of 475 ft. Consequently 
a larger portion of Kimmeridge clay is exposed on the west 
side than on the east ; and this has wasted away, and presents 
a more sloping surface than the chalk on the east. 
I have used the terms red and grey chalk indiscriminately, 
because I believe that many beds which present no traces 
of red colour belong to this formation. 
At the north end of Burdale tunnel there is a deposit 
of upwards of 20 ft., similar in texture to the red chalk of 
Speeton, with no trace of flint, of a greyish colour, and 
showing, when broken, rich chocolate markings, resem- 
bling the black spots indicating Manganese. It contains 
terebratulse, but of a much smaller kind than those found 
so abundantly at Speeton. A similar formation, or rather 
the same, appears at another point nearer North Grimston, 
exposed for a length of several hundred yards on the same 
east side of the valley. On the west side it also appears at 
the base of the chalk, opposite Wharram station (where there 
are springs at an elevation of 475 ft.), with the same peculiar 
markings. It occurs also at Duggleby and Nova. It is not 
white chalk ; it cannot be called chalk marl exactly, though 
at Nova and other places it is friable and clayish ; but it 
must be the equivalent of the formations known in the south 
under the terms Chalk Marl, Upper Greensand, and Gault. 
In fact, since writing the above, I have satisfied myself 
that the grey and red chalk are parts of the same forma- 
