42 — 
of which together with the rock platform in front of it, is 
submerged. Such a cliff must of course have been cut before 
submergence took place, at a time when no reefs were 
present to obstruct wave action. These various features are 
manifestly of easy determination, but it is remarkable to see 
how often they have been overlooked. 
In contrast to the irregular shore lines above referred 
to, are the simple or almost rectilinear shore lines which 
frequently accompany coasts of recent uplift, formed of 
marine sediments partly consolidated and but little eroded. 
Such coasts are usually bordered by a low bluff a few feet 
in height and a smooth beach, and they are rarely fringed 
with reefs. This seems to show that coasts of uplift such 
as these do not afford good conditions for coral growth, 
apparently because the loose sediment of the beach and the 
off-shore sea bottom does not provide points of attachment 
for coral larvae. Coasts of this kind are reported along the 
southern side of Java and Sumatra, but the accounts that I 
have found of them are very brief. I should be glad to 
know more about them. If with further observation it 
appears to be very generally true that coasts of emergence 
of this kind are free from reefs, it would lead to the infer- 
ence that coasts where reefs occur have suffered submergence, 
and this inference would be confirmed if such coasts are 
universally embayed. As far as my reading has gone, such 
is the case. 
Coasts are also reef-free where large rivers have built 
forward extensive deltas, which as they expand on either 
side of the river mouth may overwhelm reefs previously 
formed there. This may be the case either on coasts of 
emergence or coasts of submergence, but of course in both 
cases the formation of a large delta implies a large land 
area and a considerable rainfall to supply a large river, and 
a considerable period of time for the river to work. Al 
the examples that I have found of large deltas confirm the 
implications of this paragraph. 
