PEOCEEDINGS OF GEOLOGICAL SOCIETIES. 
191 
Oise, which is only separated by a watershed six miles broad from that of 
the Somme, passes from it into the latter valley. 
2. The presence of freshwater shells in some of the intercalated beds, 
many such as live in clear and rapid streams, indicates a probable fluviatile 
origin for these deposits. 
3. The mammalian remains and land shells give evidence of dry land. 
The occasional occurrence of bones in the position they hold during life 
shows that the carcases and limbs of animals were dropped into the old 
shingle before they were freed from their integuments, or within a short 
time after death, whilst the perfect state of preservation of the land shells 
is an indication of their not having been transported far. 
All these characters tend to prove that these beds are to be referred to 
old river action. This, liowever, must have taken place when the river 
occupied a level about 100 feet higher than it does now. It is true that 
similar gravels, containing similar mammalian remams and also flint im- 
plements, occur at lower levels (forty feet) in the valley, whence it is in- 
ferred that similar causes were in operation when these also were de- 
posited. But it is plain that the two could not have been deposited at the 
same time. For the deposition of the high-level gravels on the supposi- 
tion that the valley had been previously excavated, would have required a 
river at some times filling a channel more than a mile wide and 100 feet 
deep— a state of things not to be accounted for under any circumstances. 
The alternative therefore of a river flowing at the higher level and gradu- 
ally excavating its channel is adopted. 
The character of the climate may be inferred from the fauna. The 
land and freshwater shells are of species now living in France, but they 
also range as far north as Kussia, Finland, and Siberia. They are there- 
fore such as, though occurring in temperate climates, are capable of exist- 
ing in high northern latitudes. The animal remains furnish more positive 
testimony. The woolly mammoth and rhinoceros were fitted by their 
coating to endure the rigours of a cold climate, such as Hussia and Sibe- 
ria, where their remains abound, and where they seem to have fed on ve- 
getation common to such latitudes. A species of tiger now lives in Central 
Asia, and is often tracked and hunted down in the winter on the snow and 
frozen lakes of that region. The reindeer, of which we have the remains 
in the vaUey of the Sorame, and the musk ox, which occurs in the same 
deposits in the valley of the Thames, indicate still more clearly the north- 
ern tendencies of this group. There is a difliculty about the hippopota- 
mus, but the elephant and rhinoceros originally presented the same difli- 
culty ; and there seems no reason why in this case also the extinct species 
should not be found to have been fitted to live in a severe climate. 
These conclusions are corroborated by the physical phenomena. Mr. 
Prestwich pointed on the large section to numerous blocks of sandstone 
but little worn, and varying in weight from half to five tons, which could 
hardly have been carried and deposited, as now found, by water alone. 
He also showed various contortions in the upper beds of gravel (whilst the 
lower ones were hardly disturbed), and in the laminated sands overlying 
them. These he attributed to ice-action. The blocks, to transport from 
places higher up the valley on ice-floes at the breaking up of the ice in 
the spring, and the contortions to the grounding of ice-floes on the soft 
sand and loose gravel, impinging into them and piling up the gravel, as 
now occurs on the banks of some of the Canadian rivers. He pointed es- 
pecially to the pendent masses of brick-earth isolated in the upper part of 
the sands, and which he attributed to angular masses of ice brought down 
