104 
ELEMENTS OF GEOLOGY. 
are, upon the whole, extremely partial, and are often entire¬ 
ly wanting in districts composed of argillaceous and sandy 
formations, which must, nevertheless, have been upheaved 
at the same time, and by the same intermittent movements, 
as the adjoining harder rocks. 
Escarpments. —Besides the inland cliffs above alluded to 
which mark the ancient limits of the sea, there are other ab¬ 
rupt terminations of rocks of various kinds which resemble 
sea-cliffs, but which have in reality been due to subaerial de¬ 
nudation. These have been called ^‘escarpments,” a term 
which it is useful to confine to the outcrop of particular 
formations having a scarped outline, as distinct frgrn cliffs 
due to marine action. 
I formerly supposed that the steep line of cliff-like slopes 
seen along the outcrop of the chalk,.when we follow the edge 
of the North or South Downs, was due to marine action; but 
Professor Ramsay has shown* that the present outline of the 
physical geography is more in favor of the idea of the escarp¬ 
ments having been due to gradual waste since the rocks were 
exposed in the atmosphere to the action of rain and rivers. 
Mr. Whittaker has given a good summary of the grounds 
for ascribing these apparent sea-cliffs to waste in the open 
air. 1. There is an absence of all signs of ancient sea-beach¬ 
es or littoral deposits at the base of the escarpment. 2. 
Great inequality is observed in the level of the base line. 
3. The escarpments do not intersect, like sea-cliffs, a series 
of distinct rocks, but are always confined to the boundary¬ 
line of the same formation. 4. There are sometimes differ¬ 
ent contiguous and parallel escarpments—those, for exam¬ 
ple, of the greensand and chalk—which are so near each oth¬ 
er, and occasionally so similar in altitude, that we can not 
imagine any existing archipelago if converted into dry land 
to present a like outline. 
The above theory is by no means inconsistent with the 
opinion that the limits of the outcrop of the chalk and 
greensand which the escarpments now follow, were original¬ 
ly determined by marine denudation. When the south-east 
of England last emerged from beneath the level of the sea, 
it was acted upon, no doubt, by the tide, waves, and cur¬ 
rents, and the chalk would form from the first a mass pro¬ 
jecting above the more destructible clay called gault. 
Still the present escarpments so much resembling searcliffs 
have no doubt, for reasons above stated, derived their most 
characteristic features subsequently to emergence from sub¬ 
aerial waste by rain and rivers. 
* Physical Geography and Geology of Great Britain, p. 78. 1864. 
