202 
THE GEOLOGIST. 
tliem off, carrying away the debris to form tlie Tertiary mud and 
sands, which in turn — uplifted, too, Math the expanding ground — 
were also partly shced away, leaving the patches and remnants we 
have observed upon the summits of those chalk downs, which record 
the first act in the long period of denudation associated with the uprise 
of the Wealden tract. Slowly in this way did the sea do its antago- 
nistic work, until the inner domes of gault and greensand were cut 
down to nearly level plains encircling one and another round the 
central Wealden beds, which, like an island, stood out last in the 
midst. 
Nor is the story ended now. England and France were then 
united lands ; no " narrow straight" separated two nations of emula- 
tive men, but the hairy mammoth, the giant elk, the thick-skinned 
hippopotamus, and other of the great beasts of that marvellous age 
of gigantic forms which preceded and joined on to the age of man the 
ages of the irrevocable past wandered across and lived and bred in 
the forests, caves, or marshes of our land. 
Slowly as the intumescence proceeded, there opened out wider and 
■wider a long fracture through the uprising land, up which the sea 
washed daily and nightly, with high swelling tides, that, pent up by 
the cliff-walls of the crack, eddied back at ebb with monstrous force, 
and carved out at either end the triangular edentations which still 
form the openings of the British Channel. Sweeping round in their 
eddyings as restrained by the ridge of land that formed the barrier 
to their onward passage, these pent-up tides scoured the Wealden 
plains, and strewed the bases of the downs with half- worn flints and 
gravel. To explain this more fully I have drawn a rough sketch of 
the English Channel, with the narrow neck of land which may be 
presumed to have existed there during at least the early part of the 
Pleistocene age. 
We all know that the great tidal wave striking the land at the 
Lizard Point, in Cornwall, parts in two, or bifurcates, one tide rush- 
ing up the .Channel, the other swinging round the whole extent of 
the coasts of Wales, Scotland, and the East of England, until it 
meets and collapses with the Channel tide, off Pegwell Bay. 
In those geologic times to which we have referred, the nan-ow 
isthmus which stretched across from Folkestone to Boulogne barredthe 
