RIVER AND LAKE DEPOSITS 183 
that of the bottom of the stream are raised above the 
level of the water in which it is made, so that the river 
is often obliged to change its course from one part of 
the plain to another. This is very well shown in the 
delta of the Yellow River of China, which frequently 
Fig. 94. 
Delta in Lake Cayuga, Ithaca, N. Y. (see Fig. 96), overflowed by flood water. 
changes its mouth during flood, not only shifting its 
course to a place many miles away, but causing a ter- 
rible destruction of life and property. 
This branching and changing of the river mouth, 
builds a triangular shaped deposit, which in the Nile 
so closely resembles the Greek letter A (Fig. 95), that 
