676 RECORDS. 



SECTION OF GEOLOGY AND MINERALOGY. 



December i8, 1899. 



Section met at 8:15 P. M., Professor J. J. Stevenson, presiding. 

 The minutes of the last meeting of Section were read and ap- 

 proved. 



The following program was then offered : 



J. F. Kemp, (1) Recent Theories Regarding the Cause 

 OF Glacial Climate. 



(2) Metamorphosed Dikes in the Mica Schists of Morn- 

 iNGSiDE Heights. 



W. D. Matthew, Notes on the Geology of the Laramie 

 Plains and Rattlesnake Mountains in Wyoming. 



Summary of Papers. 



During the subsequent discussion of the first paper by Pro- 

 fessors R; E. Dodge, D. S. Martin and others, Professor Stev- 

 enson called attention to the fact that the great excess in the 

 area of the peat bogs on the surface of the earth, during the 

 present period, over that of the swamps which prevailed during 

 the Carboniferous, shows the little foundation for the hypothesis 

 of an excess of carbon dioxide in the atmosphere during the 

 formation of coal. 



Dr. Julien also pointed out, in reference to the theoiy of the 

 refrigerating influence of the absorption of carbon dioxide from 

 the atmosphere, during the decay of rocks, that this effect may 

 have been more than offset by the heat produced during the 

 accompan}'ing absorption of oxygen. 



In the discussion of the second paper. Dr. Julien acknowl- 

 edged the resemblance of outcrop of black hornblende schist 

 to a sheared dike, produced by its strong constrast in color with 

 the enclosing light gray micaceous gneiss ; and by the sharp lines 

 of separation of the schist from the highly tilted beds on either 

 side, as if thrust up from below. But this is but one of hun- 

 dreds of exacth' similar outcrops in New York and Westchester 

 Counties. All are intercalated, however, as thin beds in the 



