133 
It thins out westward, but rapidly thickens to the east, whilst 
nearer the river-mouth, which seems to have been at Sheppey, in 
Kent, abundant remains of tropical fruits, turtles, sharks, and 
other fish testify to the tropical climate which then prevailed. No 
fossils are found at Studland, but in the London Clay of Alum 
Bay some marine shells occur. At the close of this period the 
sea-bed was gradually raised, much of the London Clay being 
probably planed off in the process. An extensive but low-lying 
land surface, extending for many miles into what is now the Eng¬ 
lish Channel, and northward to a little beyond the Thames Valley, 
now appeared. Through this flat country a large river 
flowed down from the west. No doubt this began in a small way, 
but, as the westward land slowly rose, the drainage area greatly 
increased until it became a mighty river which, in size, rivalled 
the modern Ganges or Mississippi. Its watershed included a vast 
land area in Devonshire, Cornwall, and far out into the Atlantic, 
much of which land has since vanished. At the commencement 
of the Bagshot Period this river entered the sea near Selsey Bill, 
and its width, as evidenced by the Bagshot Sands in this district, 
must have been many miles. It was shallow and sluggish, though 
subject to floods which carried its waters occasionally far to the 
north, and probably also to the south. The material brought and 
deposited shows that the river drained a great granite district, 
for the quartz sand and pipe-clavs have been derived from decom¬ 
position of granite. The same process is now proceeding on a 
small scale in deposits left by streams from Dartmoor, and, in 
Cornwall. 
During the Bagshot Period the land began to slowly sink 
again, and the sea to gradually encroach upon the river’s mouth 
from the east. As we have seen,this occurred in three stages,during 
the first of which the pipe-clays of Corfe and around Poole Har¬ 
bour, and the variegated sands of Studland were formed. No 
leaves are now found in these clays, probably because they are 
worked at a lower level, but formerly they were abundant, con¬ 
sisting chiefly of deciduous forest-trees, fig-leaves, Leguminosae, 
Aralia, Myrtle, and others. These were considered by Mr. 
Gardner as of the same age as the leaf beds of Alum Bay, and 
belong to the Lower Bagshot Period. The Alum Bay bed has 
however, now been worked out, and no leaves have been found 
there for some years. 
Following these pipe-clays and sands of the Lower Bagshot 
age, we find a gap of probably ioo feet of strata which have been 
denuded off where Poole Harbour now exists, and we next meet 
with the Middle Bagshots or Bournemouth Freshwater Beds in 
the cliffs from Canford to Bournemouth. The conditions as re¬ 
vealed in these strata had evidently changed. _ The river had be¬ 
come more rapid, for pipe-clay only occasionally occurs in pockets, 
indicating little backwaters where the current was very feeble and 
permitted the fine clay to deposit slowly. But the bulk of the 
white clay was carried out to sea in solution and had few oppor- 
