THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Jl-rt. XXIII. — The Bearing of Physiography upon Suess' 

 Theories;* by W. M. Da vis. 



Contents : — Three conclusions reached by Suess. Observations on the 

 Tian Shan Mountains and on the Steppes north of the Tian Shan. Pene- 

 planation of these regions, followed by uplift of the mountains. The 

 existing Tian Shan ranges are not demonstrably the result of tangential 

 movement toward the south. Other examples of mountains carved in 

 uplifted peneplains. Suess' theory of horsts ; the great area of subsidence 

 that it requires. Improbability that horsts have stood still while all the 

 rest of. the earth subsided. Horsts .are probably the result of local uplifts, 

 while all the rest of the earth remains relatively undisturbed. 



The eminent Austrian geologist, Professor Eduard Suess, 

 has emphasized three conclusions of his researches. Uplifts 

 are limited to mountain belts, where tangential pressure has 

 acted to produce a resultant uplifting force ; mountain ranges 

 are of unsymmetrical structure, as a result of tangential move- 

 ment, and not symmetrical as a result of axial uplift ; plateau- 

 like masses owe their altitude, not to their own uplift, but to 

 the subsidence of the surrounding lower areas. Although dis- 

 placements are elaborately discussed, it is notable, as has been 

 pointed out by various students of Suess' works, that he gives 

 only a minimum of attention to the processes and results of 

 erosion, whereby so many features on the face of the earth 

 have been given their actual expression. The present article 

 offers some considerations on this aspect of the subject, and' 

 leads to conclusions that differ from those reached by Suess. 



As a member of Professor Raphael Pumpelly's Carnegie 

 Institution expedition to Turkestan in 1903, I had opportunity 

 of crossing the western ranges of the Tian Shan mountain 

 system, where the occurrence of a curious flat-topped range, 



*Eevised, January. 1905, from a paper presented before the Eighth Inter- 

 national Geographic Congress in Washington, September, 1904. 



Am. Jour. Sci. — Fourth Series, Vol. XIX, Xo. 112. — April, 1905. 

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