ORIGIN OF MO UNTAIN RANGES. 553 



And such indeed seems to have been the fact. For if all the 

 strata which have been removed from existing plateaus and 

 mountains were restored, it would make an incredible height of 

 land. At least 10,000 to 12,000 feet have been carried away by- 

 erosion from the Colorado Plateau region and yet 8,000 feet 

 remain. At least 30,000 feet have been worn away from the 

 Uinta Mountains and yet 10,000 feet remain. Evidently there 

 has been a rise pari passu with the lightening by erosion. 



May we not then safely generalize? May we not conclude 

 with Dutton that the earth in its general form and in its greater 

 inequalities is in a state of gravitative equilibrium — that the 

 earth is oblate spheroid, only because this is the form of gravi- 

 tative equilibrium of a rotating body ; that ocean basins and 

 continental protuberances exist, only because the materials 

 underlying the former are denser, and underlying the latter 

 lighter than the average. It is true that the spheroid form of 

 the earth and the sinking and rising of the crust by load- 

 ing and unloading may be explained on the supposition 

 that the earth is liquid beneath a thin crust, but to this 

 view there are three fatal objections. 1. The cosmic behavior 

 of the earth is that of a rigid solid. This I believe to have been 

 demonstrated. 2. The existence of the present great inequali- 

 ties of the earth would be impossible, except under the most 

 improbable conditions. For example, if the earth be fluid then 

 the crust must rest as a floating body. But if so, then, by the 

 laws of floatation, for every continental protuberance on the 

 upper side there must be a corresponding protuberance in 

 reverse on the other side of the crust, and for every great pla- 

 teau or mountain range there must be a corresponding plateau 

 or mountain range in reverse. And taking the difference of 

 specific gravity of the floating crust and the supporting liquid 

 to be as great as that between ice and water, these reverse ine- 

 qualities must be ten times as great as those at surface ! Can we 

 accept so violent an hypothesis? But (3) repeated experiments, 

 especially very recent ones by Carl Barus, 1 prove that rocks 



'Am. Journal, vol. 45, p. I., 1893. 



