MOUNTAINS 319 
The Japanese Islands and the Last Indies are 
instances of mountains that are even now growing; 
and yet plants and animals, and man himself, are 
able to dwell upon them as they rise, and man is 
scarcely aware of their growth. In some cases the 
uplift of mountains appears to have been so slow, that 
rivers have been able to maintain their courses across 
them as they rose; at least, this is the interpretation 
placed upon some rivers, such as the Green River of Utah, 
which cuts directly across the high Uintah Mountains. 
One of the evidences of present mountain growth 
is found in the occurrence of earthquakes, which are 
often due to the slippimg of the rocks as they break 
and move. A second evidence is the occurrence at 
the surface of actual breaks, or faults, on one side of 
which the land has been raised. Sometimes these 
movements of the rocks have been witnessed by man 
(pp. 294 and 358). 
Of slow growth in the past, there is also evidence. While 
mountains have been rising, rivers have sometimes been dammed, 
and locally transformed into lakes, in which extensive deposits of 
sediment have been laid down. In some cases these have been 
upturned and folded into the mountains, the changes all occur- 
ring slowly, so that before the complete cycle was passed through, 
time enough had elapsed for the extinction of some kinds of life, 
and the development of new types. By this, the development of 
the mountains is known to have extended through ages. More- 
over, the fact that rocks are folded, instead of shattered, indicates 
slow rather than rapid growth. 
