Crosby.] 488 [March 7, 



popular teacher, in whom a deep insight into the workings of nature 

 and an exceptional capacity for the highest scientific work were 

 combined with a rare talent for generalization and a most winning 

 simplicity and attractiveness of manner. 



Resolved: That as members of this Society we recall with sad- 

 ness, but not without a sense of mournful pleasure, his many 

 amiable and noble personal qualities which endeared him to us in- 

 dividually and we would extend our cordial sympathy to his be- 

 reaved family in their great affliction. 



Professor LLyatt seconded the resolutions and they were unani- 

 mously adopted by the Society by a rising vote. 



General Meeting, March 7, 1888. 



The President, Prof. F. W. Putnam, in the chair. 



A letter from Mrs. Asa Gray, thanking the Society for the res- 

 olutions of sympathy adopted at the last meeting, was read. 

 The following paper was then presented : 



GEOLOGY OF THE BLACK HILLS OF DAKOTA. 



BY W. O. CROSBY. 



Introduction. 

 The first systematic examination of the geology of the Black 

 Hills was made, by the lamented Prof. Henry Newton, under the 

 auspices of the United States Geological Survey, in the summer 

 of 1875, before the Hills were opened to civilization. His report, 

 which was not published until 1880, three years after the author's 

 death, is, considering the great difficulties under which he labored, 

 wonderfully comprehensive and accurate. Although the dozen 

 years which have elapsed since Newton's survey have witnessed the 

 rapid settlement of the Black Hills and the development of the 

 mineral resources of the district, they have added very little to our 

 knowledge of the geological structure of the Hills. Newton's me- 

 moir still stands essentially intact ; and, although such of my ob- 

 servations and conclusions as seem to contravene his work must 



