BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 33, PP. 273-286 JUNE 30, 1922 



THEOKY OF ISOSTASY— A GEOLOGICAL PROBLEM * 



BY WILLIAM BOWIE 



(Presented before the Society December 29, 1921) 



CONTENTS 



Page 



Introduction 273 



Extent of isostatic investigations 274 



Relation of gravity anomalies to topography 274 



Relation of isostatic gravity anomalies to geologic formation .' 275 



Isostatic adjustment of delta formations 276 



Completeness of isostatic adjustment 277 



Depth of compensation 278 



Regional distribution of compensation 279 



Mountain formation by vertical versus horizontal movements 280 



Introduction 



It would be inappropriate, at a meeting like this, to consider in detail 

 the accuracy of the geodetic observations on which the investigations in 

 the theory of isostasy are based, and to give detailed accounts of the 

 methods employed in making investigations. Many articles have been 

 published which deal with the geodetic observations and with the isostatic 

 investigations which are, no doubt, familiar to you. They can be con- 

 sulted by any one wishing to make an exhaustive study of the subject. 2 



1 Manuscript received by the Secretary of the Society December 22, 1921. 

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



2 John F. Hayford : Figure of the earth and isostasy from measurements in the United 

 States. U. S. Coast and Geodetic Survey, 1909. (No number.) 



John F. Hayford : Supplementary investigation in 1909 of the figure of the earth and 

 isostasy. U. S. Coast and Geodetic Survey, 1910. (No number.) 



John F. Hayford and William Bowie : Effect of topography and isostatic compensa- 

 tion upon the intensity of gravity. U. S. Coast and Geodetic Survey Special Publication 

 No. 10, 1912. 



William Bowie : Effect of topography and isostatic compensation upon the intensity 

 of gravity (second paper). U. S. Coast and Geodetic Survey Special Publication No. 12. 

 1912. 



William Bowie : Investigations of gravity and isostasy. U. S. Coast and Geodetic 

 Survey Special Publication No. 40, 1917. 



H. J. Couchman : The pendulum operations in India and Burma. Professional Paper 

 No. 15, Trigonometrical Survey of India. 



Sidney Burrard : Investigations of isostasy in Himalayan and neighboring regions. 

 Professional Paper No. 17, Trigonometrical Survey of India. 



XVIII— Bull. Geol. Soc. Am., Vol. 33, 1921 (273) 



