LAMPLUGH : GLACIAL SECTIONS. 
37 
with none, and much might be learnt from a study of their mutual 
relations. 
I regard the whole of the beds above the Purple Clay as of 
fresh-water origin, but shall be better able to submit my reasons 
after I have described the di-ainage sections. 
I suggested last year that the intrusions and contortions 
between the Purple Boulder clay and gravel might result from the 
movement of ice in fresh-water. I have been confirmed in this 
view by finding similar disturbances amongst undoubtedly fresh- 
water beds in some sections shown in the banks of Watermill 
Beck, a small stream which empties itself across the beach about 
three miles to the south of Bridlington Quay. The great thickness 
of undisturbed clay and sand overlying the seat of disturbances in 
Figs. 1 and 2, shows conclusively that it is not a recent surface 
movement that has affected the beds. At the same time I may 
note that after much rain, water is shed pretty freely from the 
gravel above the boulder-clay, and also that the lower layers of 
the overlying warp are sometimes slightly drawn downwards into 
the crushed gravels. 
The stratified band in the Purple Clay is another point which 
must not be forgotten by the glacial theorist. At first glance the 
stratification might be supposed to occur at random throughout 
the mass of the clay, owing to the constant change in the height 
and position of the band in a cliff-face always in some degree 
masked by landslips (which come and go over every point of the 
section at a surprising rate), but when once noticed, there is no 
difficulty in tracing it as long as the boulder-clay is visible. 
The material of which it is composed differs so slightly from 
the clay above and below, that it has almost certainly been derived 
from the same source ; yet there can be no doubt that this 
material has been sorted and deposited in water, for sometimes 
streaks of sand make their appearance along every bedding plane. 
It cannot therefore be directly the product of land ice ; neither is 
