184 DAVIS : SECTIONS IN THE LIASSIC AND uOLITIC ROCKS OF YORKSHIRE. 
ward, in the narrow gorge of Howedale Beck, there is a section of the 
Ironstone Series to a depth of 80 feet, in which it is observed that 
the thick beds of ironstone of the district further north have dis- 
appeared and are represented by bands of nodules. The shales are 
more clayey and decidedly less sandy than in other sections. The 
outcrop from this point is lost under the Boulder Clay until Hawsker 
is reached. At Hawsker Bottoms a very complete section about 100 
feet thick is obtained (fig. 5). 
FIG. 5. — SHORE PLAN FROM HAWSKER TO ROBIN HOOD'S BAY. 
The Upper Lias comprises thick beds of argillaceous shale, in 
the upper part grey in colour changing to nearly black in the lower ; 
it has a nearly constant thickness of 240 feet. It may be roughly 
divided into three parts : — 
1. Soft grey micaceous Alum Shale (with Ammonites communis, 
A. elegans, A. bifrons, &c, and Ledaovum), the Jet Rock is 
at the base. 
2. Hard dark shale, with pyritous doggers ; the characteristic 
fossils being A. serpentinus and Inoceramus dubias. 
3. Soft or grey shale, with the very restricted A. annulatus. 
The Grey Shale rests immediately on the ironstone series of the 
Middle Lias, and consists of shale which weathers soft and grey. 
Two bands of impure earthy ironstone occur close together about the 
the middle of the bed, enclosing A. annulatus, the characteristic 
fossil, in great abundance. Belemnites cylindricus occurs on about 
the same horizon as well as many other fossils ; otherwise these beds 
are remarkable for the paucity of their fossils. These shales occur 
on the east side of the fault at South Cheek on Peak Steel. The 
