BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 33, PP. 333-336 JUNE 30, 1922 



FOLDING OF MOUNTAIN RANGES— THE ARGUMENT FKOM 



ISOSTASY 1 



BY SIR SIDNEY BURRARD 2 



(Read before the Society December 29, 1921) 

 CONTENTS 



Page 



Introduction 333 



Mountain formation by vertical expansion 334 



Geological structure of Himalayas 335 



Relation of isostasy to mountain formation 335 



Introduction 



The hypothesis that mountain ranges have originated from the shrink- 

 age of the earth's core away from its crust and from the consequent 

 wrinkling of the crust has not met with support from geodesists in India. 

 In 1858 Pratt's investigations of Himalayan attraction and compensation 

 raised serious objections, and these were subsequently strengthened by 

 the brilliant writings of Dutton. 3 Pratt was a mathematician and Dutton 

 was a geologist. Pratt regarded the subterranean compensation of the 

 Himalayas as a proof that these mountains had arisen from below by the 

 vertical expansion of rocks in the crust. But even before Pratt had pub- 

 lished his conclusions the Himalayan geologist, Strachey, had put for- 

 ward an opinion, based on geological grounds, that the origin of the 

 Himalayas had been vertical uplift. 4 And the idea of a planetary core 

 contracting independently of its outer shell was forcibly opposed by Os- 

 mond Fisher, also a geologist. 5 



1 Manuscript received by the Secretary of the Society November 17, 1921. 

 This paper is one of a series composing a symposium on isostasy. 



2 Introduced by William Bowie. 



3 Philosoph. Trans. Royal Society London, 1858. 



Bull. Philosoph. Soc. Washington, vol. xi, 1892, pp. 51-64. 



4 Quart. Journ. Geolog. Soc, vol. vii, 1851, p. 292. 



5 Physics of the earth's crust. 



(333) 



