388 
LAMPLUGH : GLACIAL SECTIONS. 
4, Fiuely laminated chocolate -coloured clay, entirely free from stones. 
This only occurs in detached and crumpled patches in section 
No. 1, but is seen in place and almost undisturbed in section 
No. 2, where it has above it a thin seam of sand, (lb) and 
below an inconstant layer of earthy chalk wash. ( 4c.j 
5. Dark greenish-blue Boulder Clay (the Basement Clay): more 
sandy than the Purple Clay, and of a patchy streaky nature : 
includes masses of fine clay and mingled sand aDd clay, often 
containing arctic shells, generally crushed (5c, the ' Bridlington 
Crag) : has above it in places a sandy silt with pebbles, 56. 
(probably a rearrangement or wash from its surface.) This 
division is only seen in section No. 1 , but it is present on the 
beach opposite No. 2. 
Detailed description. Section No. 1 slopes gradually from 
south to north ; forming- the southern side of a hollow which reaches 
its lowest level just beyond the section. Section 2 forms the 
north slope of this hollow. 
The Fresh-water Marls (1) occupy and partially obliterate 
this hollow, coming' in at about the same level on either side, at 
first very thin and interrupted ; but thickening rapidly as the cliff 
sinks, they attain a maximum of about 7 feet near the middle of 
the depression. They consist of a very fine, tenacious, elastic 
mud, arranged in bands varying in colour from a dirty white to a 
deep bluish-black. They contain many fresh -water shells of exist- 
ing species and roots and other traces of plants, and at one time 
showed in their midst where thickest, a thin band of peat with 
wing-cases of beetles and small seeds, but this has disappeared as 
the cliff has wasted back. They rest unconformably on an uneven 
and eroded surface of contorted gravel, filling up many unequali- 
ties thereof. In places there is a few inches of rearranged gravel 
immediately below the marls and conformable to them. 
The Gravels (2) on which these marls rest, show throughout 
signs of great disturbance, being strangely contorted and crushed 
— often compressed into vertical folds ( see enlarged section 3 ) and 
often ending abruptly against boulder-clay (between C and J) of 
