BLAKE : EAST YORKSHIRE. 
21 
events commenced, which had but little relation to those that 
went before. 
The first change appeared in the direction whence the 
sediment was derived. No longer it came in a regular 
though slow manner from the west, but rapidly-increasing 
sandbanks were formed, now known as Kelloway rock. The 
largest followed to a certain extent the line of the most 
northerly deposits, from Scarborough to the Roulston Scar, 
while another series were deposited along a southerly line 
from near Malton to the Humber. After this the whole area 
slowly sank, and the line of separation between the true 
Yorkshire and Lincolnshire areas became nearly obliterated. 
The deepened water admitted of a clay deposit, derived 
possibly from a still further depression of the carboniferous 
area, bringing the coal measures once more beneath the 
action of the denuding forces. This, the Oxford clay, 
spread over the whole area, and united Yorkshire again to 
the south. It lay thinnest where the Kelloway rock was 
thickest, and vice versa; but was, as far as can be told, 
nowhere absent. In the Yorkshire basin, however, where the 
deposits had been so thick, the deposition seems to have 
rapidly overtaken the depression, and sand once more 
collected; and in the shallows towards the shore of the 
Pennine chain to be, corals established themselves. Colonies 
of these zoophytes also established themselves further west, 
where Hackness is now ; but in the deeper waters towards 
the south, where but little deposit had previously taken place, 
not the sign of a coral ever appeared, but the clay kept falling 
down in a dull monotony. 
The Yorkshire basin now once more began to teem with 
marine life, which had so long been almost deprived of it; and 
spite of its more northern climate, developed masses of lime- 
stone from the worn-down fragments of corals living near 
the spot that put to shame the products of the. tiny reefs of 
