LAMPLUGH : NOTES ON THE WHITE CHALK OF YORKSHIRE. 185 
the headland. I liave suggested" that the explanation is that the 
Chalkless gravels were washed from the margin of the glacier lying 
to the eastward, while the Chalky gravels were swept down the 
valley from the bare Chalk Wolds to the westward, and the alterna- 
tions were produced where the floods from opposite sides poured into 
the same hollow. 
Part II. Notes on the Age and Physical History of 
Flamborough Head. 
The foregoing descriptions will serve to elucidate the stratigraphy 
of the headland, and in conclusion a brief retrospect of its geological 
history may be permissible. 
Throughout the Upper Cretaceous period this region, in common 
with tlie whole of eastern and southern England and the greater part 
of Central Europe, lay submerged beneath the sea. The probable 
depth of this sea is still a matter of debate. By some geologists it is 
held that the Chalk was formed at great depths like the Globigerina- 
ooze of the Atlantic Ocean, while other students of the subject con- 
sider that the deposit may have accumulated in comparatively shallow 
waters. As to the probable westerly bounds of this Upper Cretaceous 
Sea there are also, from the vagueness of the evidence, differences of 
opinion. The whole of Western England may hive been covered 
and the chalky sediments of the Eastern Counties been conterminous 
with those of Northern Ireland. But it is more probable that the 
Pennine axis and the hills of Wales, with other elevated tracts of the 
older rocks, stood above the water, forming land-areas of limited 
extent. 
There is a very pronounced thinning of all the marine Jurassic 
and Lower Cretaceous strata of the north of England in a westerly 
direction, and also a change of character indicating the proximity of 
land. The same features are repeated in the lower part of the Upper 
Cretaceous rocks, and possibly throughout the formation. f We may 
therefore assume that the deposit of Chalk attained in England its 
maximum thickness near our present eastern coast-line, and that 
* Drifts of Flamboroupjh Head," op. cit.,'p. 421. 
t See \V. Hill. Quart. Journ. Geol. Soc. vol. xliv., p. 320 ; also Lamplugh. 
Proc. Yorksh. Geol. and Polyt. Soc, voL xiii., p. 76. 
