66 Notes on the Geology of South Ferriby. 
.\ reference to the numbers on this section will perhaps make 
the following description clearer :— 
In (1) we have the purple boulder clay, which occurs at the 
base of the cliffs and on the beach towards the east end of the 
section. It is exceedingly tough and crowded with boulders. 
In the same clay in ‘the corresponding section at North Ferriby 
there is an extraordinary profusion of far-travelled erratics.* 
(2.) The Upper loose foxey-red Clay, to which the name 
Hessle Clay has been given on account of its development at 
Hessle, on the north bank of the Humber. ‘This contains only a 
very occasional large boulder, its erratics being usually small and 
few innumber. Amongst them is a good proportion of porphy- 
rites from the Cheviot Hills. 
(3.). This is a lenticular patch of finely laminated stoneless 
clay, which at this point occurs between the two boulder-clays. 
It isalso found at other places in the section at the base of the 
Hessle clay. 
(4.) An extensive deposit of fine angular chalky ‘valley 
eravel,’ the denudation of which largely contributes to the beach 
material—the white flat chalk pebbles known locally as ‘ checkers.’ 
The gravel extends for a considerable distance, and attains a 
thickness of about ten feet. From its nature it has obviously not 
travelled far, and probably has been washed down from the chalk 
wolds just above, where there is a significant depression in the 
hill. This ‘wash’ or ‘flood gravel’ has occasional layers of very 
fine sand, resembling the blown sand at Sewerby near Bridlington. 
Pebbles of quartzite occur with the chalk.t 
(5.) In places upon the rubble at the top of the solid chalk is 
a somewhat puzzling laver of ripple-marked sandstone, two or 
three inches in thickness. ‘This weathers out and can generally be 
*Loe. cit. pp. 214-215, for list of these. 
7Mr. Jukes-Browne, in the Geological Survey Memoir, 1890, p. 
150, states “ at the east end of this section, where the cliff is about 20 
feet high,” the “ purplish clay was seen to pass up into the reddish clay 
of Hessle type by a gradual change of colour, and without the interven- 
tion of any loam or sand.” The section is evidently better now than it 
was in 1890, as the division between the two clays is most marked, and 
there is now no sign of any “ gradual change in colour.” 
{For the origin of these pebbles see papers by Mr. Stather and the 
present writer on “Quartzite pebbles on the Yorkshire Wolds,” 
Naturalist, 1904, pp. 9 and 56, 
De ee Se 
aes, 
