448 
THE GEOLOGIST. 
The phenomena of these deposits offer a wide scope for considera- 
tion. The causes of such an accumulation of sedimentary matter, 
the deposit of such matter anterior to the clay, and the water-worn 
faces of the bluffs, could not have occurred in the present state oi 
the surrounding country. The rush of water necessary for such 
events must have had a source much greater than any now existing 
in the district, and perhaps far distant. The quantity of water must 
have been vast. The conjecture that England at one time joined the 
continent, and that the mountains of the continent were the sources 
from which the supply proceeded, is therefore probable. It is very 
interesting to find that the waters of the Medway deposit now a 
sediment very similar to the clay filling up the faults and covering 
the highest parts of the rocks. The larger debris brought down by 
the river is also analogous to the gravel. I am thus led to the infer- 
ence that these deposits are the relics of water having considerable 
motive power. 
The principal sources of the Medway are now in the elevated por- 
tions of the Weald, but we cannot attribute the ancient "diluvial" 
waters to so limited a source. 
The lines of fracture, which constitute the principal faults, are 
parallel to the course of the Medway, and are filled almost entirely 
with clay (brick-earth), and contain the remains of mammalia, viz. 
elephant, deer, horse, and hippopotamus. The bones and teeth are 
found at a considerable depth in the clay, and much separated. I 
discovered a fragment of a jaw of a horse with five teeth in their 
sockets. There occurs also, at a depth varying from ten to twenty 
feet from the surface, a bed of freshwater shells, Li/mncea, Helix, 
and Pupa. These shells are rather sparingly distributed, but may 
be found in all the clay-pits worked on each side of the river. The 
general level of the bed is about a hundred feet above the present 
level of the water. Transverse faults cross the main lines of frac- 
ture, and these are filled with a gravelly drift of flints, chert, and 
ragstone, more or less water-worn ferruginous sand, and occasionally 
a boulder of Druid sandstone. In the gravelly detritus I have found 
detached fossils from the Lower Greensand. 
The following statement of the moving power of water, in the ' Civil 
Engineers'and Architects' Journal,' gives the rates of the force required 
for the disturbance of matter subjected to its action : — " A velocity of 
three inches per second at bottom will work upon fine clay ; six inches 
will lift fine sand ; eight inches per second, sand as coarse as linseed ; 
twelve inches per second will sweep along fine gravel; and twenty-four 
inches per second, gravel one inch in diameter." From the above 
facts it would appear that the clay, drift-gravel, etc., were not de- 
posited by the same forces, and consequently not at the same time. 
The red clay, composed of very fine particles, was deposited after 
the erosion of the rock. At that period, I presume, a great flow of 
water was wearing away the angles of those rocks which obstructed its 
course. "When this speed diminished and the water became tranquil, 
the fine clay held in suspension deposited itself at the bottom ; this 
