BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 34, pp. 231-242 June 3o. 1923 



♦ 



KOBEFS THEORY OF OEOGEXY^ 



BY CHESTER R. LOXGWELL 



{Presented before the Society Decernher 28, 1922) 



CONTENTS 



Page. 

 Brief outline of Kober's theory 231 



Theory and work of Suess 232 



Comparison of views of Suess and Kober on tlie Mediterranean mountain 



system 232 



Characteristics of the Mediterranean ranges 233 



Comparison of the Mediterranean orogen with other mountain systems . . 236 

 Mountain growth 238 



Brief Outlixe of Kober's Theory 



Professor Kober has attempted to fit all parts of the earth's crust into 

 a broad structural scheme, recognizing major units of two kinds : great 

 plates or shields, continental in size, which behave as essentially rigid 

 masses; and between them sinuous, comparatively narrow zones, which 

 are relatively weak or labile and in which the effects of deformation are 

 concentrated. These orogenetic zones are marked first by geosynclines, 

 later by great systems of folded mountains. Their positions, as well as 

 the outlines of the plates, have changed somewhat through geologic time. 

 Thus we find within some of the present rigid masses structure lines 

 that mark the sites of mountain zones in the pre-Cambrian or the early 

 Paleozoic. These were belts of weakness which have been healed or 

 welded with the passage of time, while new labile zones have come into 

 existence elsewhere. Therefore details in the structural aspect of the 

 crust have varied, but there has been continued repetition of a general 

 process. In the contraction of the earth the edges of adjacent plates 



^ A review of "Der Bau der Erde," by Leopold Kober. Berlin, 1921. 

 Manuscript i-eceived by the Secretary of the Society March 13, 1923. 

 This paper is one of a series composing a "'Symposium on the structure and history 

 of mountains and the causes of their development." 



XVI— Bull. Geol. Soc. Am., Vol. 34, 1922 (231) 



