218 GROVE KARL GILBERT— DAVIS 



Gilbert published no further contribution to the problem of isostasy until 1913; but in the 

 meantime he urged the Carnegie Institution of Washington to undertake a deep boring chiefly 

 for the determination of the temperature gradient within the earth. He spent a small part of 

 a grant of $1,000 for a preliminary investigation, and in 1904 asked for a further grant of §65,000 

 to be spent on a boring in the Lithonia district of Georgia, a district where a large granite batho- 

 litli as well as the rocks into which it was long ago intruded have been reduced to a peneplain 

 during a prolonged period of geological quiet, and where the absence of recent deformation, of 

 alternations of deposition and erosion, and of ice invasion have presumably permitted the uni- 

 form granitic mass to assume a vertical distribution of temperature characteristic of the earth's 

 crust as a whole; 6 but the recommendation came to nothing, as the grant was not made. 



• Value and feasibility of a determination of subterranean temperature gradient by means of a deep boring. Carnegie Inst. Yearbook no. 3. 

 1005. 261-287. 



