190 F. B. TAYLOR ORIGIN OF THE EARTH's PLAN 



by oceanic depression and tangential thrusts directed toward the oceans 

 from certain northern vertices, or horsts, of relatively restricted area, is 

 not adopted. In its stead an attempt is made in the closing part of this 

 paper to determine in a general way the nature of the causes producing 

 the tangential thrusts, particularly by a study of the largest definable 

 units of deformation and by the groupings which the similar and dis- 

 similar characters of these units suggest in relation to possible causes of 

 deformation. The conclusion reached is one which Suess himself hints 

 at in one of his later works, where he recognizes the possibility of a much 

 broader cause than that which he discusses in the first three volumes of 

 "The Face of the Earth.'' 



Eurasia, the greatest Unit in the Earth's Plan 

 signfflcance of the peripheral mountain arcs of asia 



Throughout his whole discussion of the mountain systems of Asia, 

 Suess dwells continually on the significance of the mountain arcs, and 

 especially on those of the peripheral belt. He notes that they all bend to 

 the southward — to the southeast from eastern Asia, to the south from 

 southern x\sia, and to the southwest and south from southwestern Asia ; 

 that they are overthrust against the northern side of the obstructing 

 tableland of Indo-Africa, and show peculiar forms which arise from 

 adaptation to the form of the obstructing mass; that the island arcs 

 along the east coast, where no obstruction was met, bend out even more 

 perfectly toward the deep depression of the Pacific ; that the southward 

 bending of the arcs indicates a connection between the different parts of 

 all this vast region and must have arisen from a common cause, and 

 finally that these characters all contribute to the conclusion that the en- 

 tire peripheral mountain system of Asia was folded toward the south by 

 horizontal thrust forces acting in that direction. It seems impossible to 

 contemplate a plan of the trend-lines of the peripheral ranges, such as is 

 shown in figure 2, without reaching these conclusions. 



The trend-lines show, with two or three exceptions, simple arc-forms 

 bending to the south along the entire front from Asia Minor to Alaska. 

 Their simplicity of form and their relations to one another are such as 

 seem to be attributable only to a single thrusting force acting throughout 

 the whole process of folding substantially in one direction, for there ap- 

 pears to be no evidence of complexity resulting from thrusts in different 

 directions, such as is found in Europe. The arc of the main range of 

 the Himalaya is about 1,500 miles long and is a curve of wonderful sim- 

 plicity and perfection. It is an almost perfect arc of a circle with a 



