213 
which may formerly have existed. In many places it is not 
more than three inches thick, and the chalk itself is fre- 
quently ploughed up and intermixed with the soil. There is, 
however, considerable difficulty in explaining the presence of 
63 per cent, of silica, while the chalk rock contains not 1 per 
cent., and also in the absence of calcareous matter, which is 
only 7 per cent, while that of the rock is 98 per cent. 
(Compare the analyses of the rock at Hessle, and the shallow 
wold soil of Bishop Wilton.) The embedded flints, how- 
ever, which pervade the whole formation, resist the decom- 
position of the atmosphere, while the carbonate of lime is 
continually being dissolved by the rains and carried away 
into the subsoil^ — hence, probably, the prevalence of the 
former, and absence of the latter earth. 
The division between the chalk and chalk marl over this 
district must be considered rather arbitrary. The embedded 
flint nodules are found through the whole formation, and are 
here of an unusually light colour. In Elloughton dale are two 
beds of chalk marl, one yellow and the other red, the latter of 
which runs at the bottom of the chalk terrace as far north as 
Pocklington. Mr. Harcourt considers this thin red band the 
representative of the Cambridgeshire gault, from the pre- 
sence of the small transparent beleranites described by Lister. 
The chalk marl is said by Professor Sedgwick to exist at 
Speeton, and the yellow and red beds alternating there to 
give the cliflf a very singular character. 
The Oolitic series consists of, in the descending order : — 
1. Kimmeridge Clay, about 25 yds. 
2. Kelloways Rock 5 „ 
3. Inferior Oolite 6 „ 
4. Lias 25 „ 
and is here characterized by the absence of the several mem- 
bers in its group, the Kimmeridge Clay being the only 
member of the upper Oolite, the Kelloways Rock that of the 
middle Oolite, while the inferior Oolite is the only representa- 
