CONTINENTAL CREEP 



355 



required^ the amount of the individual movements, or the thickness of 

 crust affected. 



At the same time, 1885, W. B. Taylor promulgated a theory that 

 mountain-folding was due to a slowing' down of the earth's rotation. 

 This acted by raising the polar areas to such an extent that gravity pulled 

 the excess matter toward the equator and folded parts of the crust. 

 Since the circumference of the earth at the equator was reduced at the 

 same time, there must have been an east-west compression making north- 

 south mountain ranges. In assigning a cause for the slower rotation, 

 Taylor adopted the idea that the friction of the tides was responsible. 

 The probability of this as a cause had long engaged the attention of 

 astronomers; it had been rejected by Fisher in 1881, and Ferrel had con- 

 cluded from astronomical observations that there had been no retardation 

 of consequence in a million years. Taylor further calculated that the 

 change in revolution necessary to account for the amount of crustal 

 shortening, which he estimated to be 10 per cent of the original length, 

 would require a former revolution of the earth in four hours. Cham- 

 berlin later (1909) arrived at similar conclusions regarding the position 

 and trend of mountain ranges. 



According to F. B. Taylor's theory of 1910, the whole crust between 

 the north polar regions and the island loops of the East Indies moved 

 southward as a mass. In Asia the horizontal motion was least in the 

 Himalayas, where the moving crust encountered the buttress of the 

 Indian Plateau, and it was greatest in the East Indies, where motion 

 was unobstructed and is stated to have been in the vicinity of 2,500 miles. 

 The immensity of this transformation was recognized by Taylor, and no 

 cause except one of the highest order — that is, astronomical — could be 

 considered sufficient. Accordingly, he postulated that the earth's revo- 

 lution was increased, with a tendency to settling of the polar areas and 

 elevation of the equatorial belt. 



The mechanism by which this polar change was transmuted into a hori- 

 zontal motion of 1,000 to 2,500 miles was conceived by Taylor to have 

 been a plane in the earth's crust dipping at a low angle toward the 

 equator; down this plane a part of the crust of the earth was supposed 

 to slide under the influence of gravity. Eeyer had already (1888) pro- 

 mulgated a simpler theory of creep, in which he considered that the sedi- 

 ments were folded by a simple sliding down the slope of the ocean basins. 

 The earlier discussion by W. B. Taylor had not gone into the difficulties 

 of the sliding process or the means of accomplishing it. All forms of the 

 tiieory pass over the element of friction, which must have had a com- 

 pelling influence. jSTear the surface of the earth this absolutely stops 



