BLAKE : EAST YORKSHIRE. 
25 
still further west, a mass of the Lias let down into the 
Trias below. 
It was now the turn of Yorkshire to be denuded, and to 
pass on to other districts the materials it had so richly 
gathered. While the central portion, protected, as has just 
been explained, by the very catastrophe which exposed the 
whole to denudation, escaped comparatively untouched, the 
two main anticlinal axes, one to the north, across the moor- 
lands, and the other to the south, corresponding to the old 
line of elevation which originally gave Yorkshire its local 
character, suffered most severely. In the north the beds were 
worn away to so thin a substance that little was left as a cap 
above the Lias ; and the denuding forces of later periods soon 
carved a way through it to produce the curious Liassic inliers 
of the moorland vales. On the south a clean sweep was made, 
and the old axis denuded to the Lower Lias. Not that much 
was required in the way of denuding, for the beds were very 
thin and many absent ; but only here and there were remnants 
left to tell what once had been. In particular, the Kimmer- 
idge clay, which must once have covered the whole area with 
no mean thickness, has only escaped here and there on the 
surface of the lower beds, as at Pickering, Helmsley, Malton, 
and Birdsal. 
But what became of all this clay ? By what must be 
considered almost an accident we are able to give some 
account of it. For at Speeton we just catch the corner, so to 
speak, of the great area where it went to rest. There, 
separated from the last of the Portlandian clays by nodules 
of phosphatic matter, such as are generally taken to be a 
sign of unconformity, we find a new series of lower Neocomian 
clays, nearly the only ones in this country, and which there 
can be but little doubt were derived from the denudation of 
the Kimmeridge clay of the elevated Yorkshire area, and 
which accounts for their local development. These are 
