STATHER : NOTES ON THE DRIFTS OF THE HUMBER GAP. 211 
the dead-level of the warp deposits continues till North and South 
Ferriby are reached. (See map.) 
At North Ferriby the land rises somewhat abruptly, and the 
bank of the river becomes a low cliff which continues for half-a-mile 
or so, and then sinks, though much more gradually than it rose, to 
its former level, under the recent river warp to the west. This cliff, 
which is at present receding somewhat rapidly under the erosive 
action of the Huniber, is locally known as Red Cliff. It has an 
average height of 16 or 18 feet, with an extreme height of 25 feet. 
The only previous description of the section known to me, is that of 
Mr. Cameron, who, however, mentions only that "At the low cliff of 
North Ferriby there is a purple chalky boulder clay, the upper part 
of which weathers red." 
The cliff at South Ferriby also rises somewhat suddenly from the 
eastern flats, attains a height of 20 feet, and then gradually sinks 
towards the west. The length of the section is about two-thirds of 
a mile. Of this section Mr. Clement Reid remarks, " The low cliff 
of South Ferriby is the only exposure of boulder clay on the south 
shore of the Humber. It corresponds closely with that seen at North 
Ferriby, and exhibits a boulder clay separated from the Chalk by thin 
ripple-marked flaggy sandstone. From this point eastward, boulder 
clay forms a belt separating the Chalk Wold from the Humber flat, 
clearly showing that the ancient Humber valley was not only deeper 
but wider than the present one, and was subsequently filled with 
drift, through which the present river is excavating its channel."t 
Description of the Beds. 
10. Chalk. — At South Ferriby, the solid Chalk which forms the 
base of the middle part of the section, and also the adjacent beach, 
belongs to the Lower Chalk. It is a hard grey rock with pink bands 
(fig 10). 
8. Rippled Sandstone. — Interposed between the boulder clay 
and the rubbly top of Ifhe soHd Chalk in the South Ferriby cliff 
* Survey Memoir, Holderness, p. 19. 
t Survey Memoir, Holderness, p. 51. 
