Ниттох.—0Оз the Formation of Mountains. 289 
11:9 yards in 2,000 years, the time during which we have astronomical obser- 
vations, or 1 inch in 41 years, 
9. If, however, for the sake of argument, we allow Mr. Fisher all he asks, 
namely, that a mountain half a mile high might be formed on every 100 miles 
since the present surface features originated, we then find that, taking the 
date as before, Mr. Fisher’s mountain has taken 11 millions of years to rise 
2,640 feet, or it has risen only 1 foot in 4,166 years, which is slower than the : 
ascertained rate of denudation, 
Mr. Fisher, therefore, is in this dilemma: either the contraction of the 
earth's radius has been so rapid that astronomers ought to have detected it ; 
or else elevation has been so slow that no land could rise above the sca level. 
10. Another important objection to the contraction theory, is that 
mountains have always been formed in those places where deposits have been 
heaviest ; while, by that theory, those areas should never rise at all. Mr. 
Fisher says that “the local pressure caused by a fresh deposit * ж will 
originate a line of elevation along its shore line or boundary,” and again, “ the 
thickness of the rigid crust being increased by the new deposit, it would offer 
an impediment to the elevation of ridges beneath it, and throw the whole 
disturbance into the region just outside its boundary.” This is exactly 
opposite to what we see in nature. 
11. In my previous papers on this subject I have pointed out that 
mountains are formed on two different plans, the one being associated with 
- volcanic rocks, the other with the crystalline schists ; but the contraction 
theory supposes that all mountain chains are identically formed. 
12. My last objection is, that this theory makes no provision for tension 
in rocks—everything is done by compression ; while faults prove tension just 
as surely as contortions prove compression. 
I am therefore of opinion that the effect on the crust caused by contraction 
has been very small, and that it has been totally obliterated by the much 
larger effects caused by deposition. 
In conclusion, I wish to explain that I do not consider it necessary that 
the whole of an area must have been under water in order that it may be 
raised by the deposition of limestone ; but that, owing to the lateral conduction 
of heat, one or more mountain ranges might project out of it as islands. Indeed, 
I believe that all high mountain ranges are the result of several subsidences 
and elevations, during which they may never have totally disappeared under 
the ocean. 
