SECOND SHALE. 81 



the place of the second shale. Similar indications of the same trans- 

 ition may be seen in several other spots. The shale is generally 

 divided by thin seams of sandstone; and this transition takes place, 

 by the enlargement of these seams into thick beds, and the consequent 

 contraction of the shale beds, which in their turn become thin seams 

 between the beds of sandstone, nay, are sometimes thrust out alto- 

 gether, leaving the sandstone to fill up their place. 



This change, which is very common in the lower beds of shale, 

 may be traced on the coast in this second shale. At a point a little 

 to the east of Cayton mill, the seams of sandstone, interstratified with 

 the shale, are enlarged ; particularly two seams or beds, which at 

 some distance beyond that point are separated by a thick bed of shale, 

 but at the point come together, the upper bed descending to meet 

 the lower, while the shale is compressed to a thin edge between them. 

 On the west side of the point, the two sandstone beds again separate, 

 and the shale between them resumes its former dimensions ; but its 

 progress, with that of the other shale beds above and below, is sud- 

 denly checked at Cayton mill ; an interruption occasioned, not only 

 by the wearing out of the upper part of the strata, at the cleft or 

 ravine that leads down to the mill; but especially by a slip in the 

 strata, at least in the higher strata, which with the alluvial beds have 

 come down on the north-west side of the mill, and removed or cov- 

 ered up the shale from thence to Scarborough. 



The slip in Cayton clifls is of a class not uncommon along the 

 coast. The lower strata have not sunk with the upper, but the latter 

 have come down in a mass over the former; and while most of the 

 shale has been pressed out from under the mass, and washed away 

 by the sea, the sandstone beds, corresponding with those which cap the 

 shale opposite Gristliorp, have come down to the beach, occupying 

 the place of the shale that is gone, and covering what has been left. 

 Portions of the shale are still visible here and there, through openings 



X 



