11 



4 



the year, to the preparation of a paper on the Iron and Copper 

 Regions of Lake Superior, which forms the first number of the 

 first volume of tlie Geological Series of the Bulletin of the Mu- 

 seum. It contains 157 pages, and is illustrated by six plates. 



The time of tlie Sturgis-Hooper professor has been chiefly occu- 

 pied in continuing the publication of the Auriferous Gravels of 

 the Sierra Nevada," which is now completed, forming Yol. YI. 

 No. 1 of the Memoirs of tlie Museum, and containing xvi and 569 

 pages, with twenty-four illustrations, — maps, plates of sections, 

 and heliographs of scenery, ^ — and two large folding maps, one of 

 which is in two sheets. This work, with the Memoir of Mr. Les- 

 quereux on the fossil plants of the same formation, completes the 

 sixth volume of the Memoirs. 



It was the intention of the Sturgis-Hooper professor to include 

 within the volume on the gravels an account of the glacial and 

 surface geology of the Sierra Nevada ; but finding the work 

 likely to expand to dimensions too large for convenience, if all 

 this matter were to be included in one volume, it has been divided 

 into two portions. A memoir entitled the " Climatic Changes of 

 Later Geological Times" has been prepared, and a portion of it 

 (120 pages) is already in type, and will be published synchro- 

 nously with the gravel volume. The remainder, which is nearly 

 all written, will be put in type and issued during the coming 

 winter. Tliis work -will form No. 2 of Yol. YII. of the Memoirs. 

 It will contain a full description of the phenomena observed in 

 the Cordilleras, indicating changes of climate during the later 

 geological periods, followed by a discussion of the bearing of these 

 facts on climatic changes in general, especially those which have 

 occurred during the most recent geological epochs, and which the 

 author believes to be still in progress. 



