626 HARMON LEWIS 



the geodetic evidence, three groups of possibilities for isostatic 

 compensation: first, the possibility of complete compensation at a 

 depth in the neighborhood of 60 to 150 miles depending on the 

 distribution of compensation; second, the possibility of an over- 

 compensation at a greater depth for land areas with probably 

 complete compensation for ocean areas; and third, the possibility 

 of under-compensation at a shallower depth for land areas with 

 complete or over-compensation for ocean areas. 



Hayford's geodetic results do not, therefore, constitute a proof 

 of the theory of isostasy. 



An incomplete compensation of the topographic features of the 

 continents can be plausibly explained without supposing the type 

 of deformation postulated by isostasy. 



There are many important phenomena which the theory of 

 isostasy will not explain. 



