370 ON THE SETEIA AND 
erly countries and of marine exuvie froma greater 
or less distance. During this submergence, ex- 
tensive deposits, both conglomerated and stratified, 
of gravel, sand, and marly clay, took place, which, 
on the subsidence of the sea-level, appeared to 
have completely covered up this land of primeval 
vegetation. The remains of this once living sur- 
face, in subsequent periods, was, and is now at 
times discovered, at varying depths beneath the 
soil, by trenching, or by the degradation of the 
tides, as at Blackpool, Crosby, and Leasowes in 
Wirral. 
The recession of the sea-level during the period 
of this emergence of the land, appeared not to 
have been uniformly gradual, but rather intermit- 
tent, as the remains of what are called sea-terraces 
or raised beaches afford very probable evidence. 
These may be observed at Clifton, round by 
Kirkham, and on by Poulton in the Fylde, in 
Walton and Leyland on this side the Ribble, and 
along the shores of the Dee and Mersey in Wirral 
and Broxton. 
Of late years, at least during the last half cen- 
tury, it would seem that the sea is again slowly 
encroaching, in some places, on the deposits which 
