182 DAVIS : SECTIONS IN THE LIASSIC AND OOLITIC ROCKS OF YORKSHIRE. 
Pholadomya Beyrichii, Schlonb. 
Ammonites capricornus, Schloth. 
A. fimbriatus, Sow. 
A. striatus, Rein. 
The Capricornus Beds at Huntcliff, near Skinningrove, and 
Colburn Nab, Staithes, contain a much greater variety of fossils 
than the section now considered. 
The Middle Lias may be divided into two parts. The Lower 
consisting of sandstones and hard shales, called the " Sandy Series " ; 
and the Upper made up of shales with bands of ironstones of variable 
thickness, denominated the " Ironstone Series." The sandstones of 
the Lower Series have a blueish tinge when newly broken, but this is 
lost by exposure. The fractured surface is often found covered with 
casts of shells, principally Cardium truncation, Gryphcca, Cymbium, 
Pecten, and Avicula. The beds are remarkable for the great 
abundance of fossils they contain ; they are between 50 and 60 
feet in thickness. Several exposures occur in the district. On the 
west side of the Peak Fault the cliff is capped by sandstone and 
sandy shales. They are seen on the left of the footway with an 
abundance of fossils : A. margaritatus, Hippopodium ponderosum, 
Cardium truncation, Gryphwa, and Dentalium, not generally very 
well preserved. From thence the sandstones form a well-marked 
terrace round the south-east side of the Bay, and disappear under 
the Boulder Clay below the Brow Alum Quarry. The Middle Lias 
rocks form a fine succession of curving terraces systemmatically 
arranged round this part of the bay ; and in Tan Beck, and less 
perfectly in other streams, good sections of the series may be 
obtained. The best section of the Middle Lias beds is obtained 
a short distance north of North Cheek of Robin Hood's Bay at 
Castle Chamber, the following is the section in descending order — 
Ft, In. 
Thin calcareous sandy band forms top of Dobson 
Nab: layers of Cardium truncation, &c. .. ... 0 10 
Hard sandy shale ... ... ... ... 4 0 
Calcareous sandy shale : Dentalium giganteum, 
Gryphcea, Cardium truncation, &c, abundant ... 5 0 
