352 
THE MODERN EPOCH. 
gone no material alteration ; the ordinary effects 
of the atmosphere, the degradation of the shores 
by the action of the sea, the erosion by river cur- 
rents of the strata over which they flow, and the 
formation of deltas, and the silting up of valleys, 
being the only physical changes that have taken place 
in the south-east of England during the modern 
epoch, and which are still in active operation. 
The existing rivers in this district are pro- 
ducing on a small scale the same effects as the 
mighty river of the Iguanodon period ; bringing- 
down from the interior the debris of the strata 
over which they flow, mixed with the bones of 
animals, and the trunks, branches, and leaves of 
vegetables, and imbedding a portion in the chalk 
valleys in a deposit of mud or silt, and transporting 
the remainder to form deltas at their entrance into 
the ocean. 
formed. The annexed figure represents the actual section presented 
by the face of this range towards the town. 
CLIFF HILLS, NEAR LEWES. 
d. The Coombe. e. Mailing road. 
/. Bridgwick chalk pit, consisting of the upper chalk. 
g. Mount Cabum. A. Southerham Corner. 
At Mailing road, on the north, the chalk marl is seen, inclined 
towards the south-east, and coming out from beneath the lower 
chalk. Approaching the deep ravine called f/ie Coombe, the loiver chalk 
forms the lower two thirds of the cliff, the upper portion being com- 
posed of the chalk. The southern side of the valley, on the 
