At 
towards the bottom of the deposit near its junction with 
the clay. The sands are generally somewhat barren, 
however, or contain only a few shallow water species. 
In some instances the sands rest on boulder clay 
or directly on the rock which is often striated below the 
deposit. When the sands rest upon the clay, as is not 
infrequently the case, the contact may be either of two 
kinds. In most cases there is a transition from one 
deposit to the other, the clay becoming sandy and gra- 
dually passing upwards into pure sand and fine gravel. 
In other cases the surface of the clay has been deeply 
trenched, apparently by stream erosion, the channels 
afterwards being filled with cross-bedded sands and 
gravels. A good example of this is shown by a section 
uncovered near the sulphite plant of the Eddy paper 
works in Hull. In such cases the sands and gravels, 
_ which are local in character and distribution and have 
not been found to contain marine fossils, are supposed 
to be due to stream deposition. 
Stratified and unstratified sands and gravels, which 
are considered to be glacial in origin, also occur in the 
district. Travelled boulders are numerous, either imbed- 
ded in the sands and gravels or lying loose on the surface 
at all elevations. 
It is generally believed that the marine sands and 
clays were deposited during the time of submergence at 
the close of the Glacial period and that they were never 
overlain by a later till sheet. Drift boulders occasionally 
rest on these beds, but their occurrence may be explained 
on the supposition that they were carried to their present 
positions by floating ice during the time of marine sub- 
mergence or by stream action aided by ice. On account 
of the general absence of boulder clay from the surface 
of the clays and the well perserved character of many 
of the marine strand lines, it does not seem probable 
that any extensive ice invasion took place after the deposi- 
tion of the clays. It is possible, however, that local ice 
tongues advanced from the highlands during the time of 
marine submergence, or after the partial subsidence of the 
marine waters and the occurrence of the moraine-like 
deposit which overlies marine clay and is well seen in 
Hull, may possibly be explained on this supposition. 
32224—93 
