196 WEE POWGINAUL HF GE QULOE Nc 
and these would be carried by streams or waves to less elevated 
regions, where they would be deposited over beds which either 
had not experienced erosion at all or had suffered but slightly. 
The pebbles would therefore be found overlying the lateral exten- 
sion of the beds from which they had been derived. 
It is still too early to say that marked shore escarpments did 
not exist. It is sufficient for the present to state that they have 
so far not been discovered, and that the failure of pebbles from _ 
decidedly lower horizons to appear, is decidedly against their 
former existence. It might be worth while to consider under 
what conditions such escarpments would be formed, and when 
they would be preserved. It is evident that during the gradual 
emergence of land above sea level any small escarpment formed 
by the sea would, on continued elevation, be exposed to aerial 
denudation which might accentuate it, but would be more likely 
to do the opposite. On the depression of the land area below 
the sea level, the same land surfaces would once more become a 
prey to the action of the waves. In either case, whether of 
emergence or depression, escarpments of any size would be 
formed only during periods when elevation or depression were 
ata standstill. The height of these escarpments would be deter- 
mined by the slope of the land surface and the sea bottom lead- 
ing up to the same, and by the length of time during which the 
land would admit of attack at practically the same levels. The 
best escarpments would not be formed during the rise of a land 
area, when the waters nearer the line of attack upon any shore 
would gradually grow shallower, but during the depression of 
the same, when any advantage gained by cutting through several 
layers of some bedded series of rocks was hardly likely to be 
lost, as the gradual increase in depth at this point permitted 
the more violent impact of the waves. Any fairly rapid period 
of depression would then preserve such an escarpment in good 
form for the future geologist. 
The failure to find evidence of an escarpment may be proof 
merely that there were no long periods of rest either during the 
elevation or depression of the land area. 
