BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 5, pp. 203-206 February 17, i894 



RELATION OF MOUNTAIN-GROWTH TO FORMATION OF 



CONTINENTS 



BY N. S. SHALER 



{Read before the Society December 28^ 1893) 

 CONTEXTS 



Page 



Introductory 203 



Limitations as to Position of Mountains 203 



Origin and Occurrence of Mountain Pedestals 204 



Causes of Mountain-uplifting above Sealevel 205 



Conclusions 206 



Introductory. — In this writing I wish to call attention to certain features 

 in the distribution of mountains which seem to me to throw light on the 

 conditions which lead to the develoi)ment of continents, and, as the points 

 to be set forth concern a considerable range of phenomena, I shall state 

 them brief! 3^ with the expectation that in some other form of publication 

 the chance may be offered for more extended presentation. 



Limitations as to Position of Mountains. — Mountains a|)pear to be limited>^ 

 to the continents or to large islands which are more or less continental 

 in their relations. This is shown by the fact that the surfaces of the 

 greater oceans are essentially destitute of islands which we can suppose 

 to be mountain-tops which have attained the surface of the water. All 

 the thalassic islands, in a word, are volcanic masses or have been brought 

 to the surface by the coral-building animals. As the average depth of 

 the sea is about fifteen thousand feet, and as there are some hundred 

 peaks in various systems which attain to more than this height, we 

 should expect, if mountains grew on the sea-floor as freely as they do 

 on the land, to find more of these elevations in that realm than we do 

 on the continental areas. The case is even stronger when we consider 

 that on the land mountains are continually subjected to erosion, an action 

 to which they would not be exposed in the oceans until they had risen 

 above the surface of the water. Although we may recognize the fact 

 that down-wearing is a concomitant and perhaps a necessary condition 

 of extended dislocation of strata, and that mountains never have had 



(203) 



