218 STATHER : NOTES ON THE DRIFTS OF THE HUMBER GAP. 
It seems not improbable that these weathered boulders of the 
Upper Clays have been derived at second-hand from the destruction 
of the Lower Clay.''' 
Notes on the Correlation of the Beds. — The difficulty and 
uncertainty attending the correlation of glacial deposits, always 
great, is necessarily increased when, as in the present case, the 
sections under discussion are isolated and far away from other 
exposures. Yet the characteristics of some of the beds just described 
are sufficiently marked and definite to invite and perhaps to justify 
comparison with other areas and sections. Besides it has been the 
opinion of observers from the time of Messrs. Wood and Rome 
onwards (for discussion of this point see Mr. G. W. Lamplugh's 
paper on "The Drifts of Flamboro' Head"), that well-marked divisions 
in the drifts exist and persist over wide areas, including Flambro' 
Head, Holderness, and perhaps Lincolnshire. And it appears almost 
certain that the deposits seen in the Ferriby sections are continuous 
with like deposits far beyond the limits of these sections. Thus 
with regard to the lowest bed, when speaking of the Hessle gravels, 
Messrs. Wood and Rome observe "at the Hessle quarry, the sand 
and gravel bed is divided from the brecciated surface of the Chalk by 
a thin bed of indurated or ripple-marked mud ; and at South Ferriby 
is divided from its superincumbent clay by a similar pan." In 
further confirmation of the extension of this bed north of the 
Humber, I may mention that a section recently visible in the railway 
cutting west of Hessle station exhibited a thin sandstone (ripples 
not seen) at the base of the boulder clay. So we may conclude that 
the special conditions which produced the rippled sands at South 
Ferriby extended at least as far as Hessle on the opposite side of the 
Humber gap. 
Mr. A. J. Jukes-Browne, who has written very fully on the 
boulder clays of Lincolnshire, has, I think, very justly referred the red 
earthy Upper Boulder Clay of both the sections described in this 
paper to the Hessle clay of Holderness, first described under that 
name by Messrs. Wood and Rome. 
* I am indebted to Mr. G. W. Lamplugh for this suggestion. 
