ACADEMY OF SCIENCES. 123 
Reeuntar Meeting, May 17, 1875. 
Vice-President Edwards in the Chair. 
Fifty members present. 
Gustave Mahé and Ernest L. Hueber were elected resident 
members. 
Joseph L. King and Pembroke Murray were proposed for 
membership. J 
Donations to Museum: Sponges and tertiary fossils from San 
Diego, by Henry Hemphill; concrete gum, from C. B. Smith; 
archil from Mazatlan, and Epiphites (Abies Douglassii), Henry 
Edwards; fragments of wood from a well 180 feet deep in Alvarado, 
Alameda County, California, from John Hall; Indian Mortar, 
from Amos Bowman; fine specimen of peacock (mounted), from 
James Lick; portion of skull of Ursus horribilis, from M. 
O’Hara; snake from Master Willie Lockington. 
Wm. Guerin read a paper on ‘‘ The Sewage System of San 
Francisco.”’ 
Mr. Stearns read a paper by J. E. Clayton, of Salt Lake, as 
follows: . 
The Glacial Period—Its Origin and Development. 
BY J. E. CLAYTON, 
In the summer of 1860, I discovered the markings and terminal moraines 
of the Glacial system of the Sierra Nevada mountains, on the head waters of 
the Merced and Tuolumne rivers. 
Upon my return to San Francisco, I reported the facts to the California 
Academy of Sciences. Since that time I have been a careful student of the 
glacial phenomena presented on the western slope of the continent. In other 
portions of the world, the phenomena of the Glacial period have engaged the 
attention of scientific investigators, ever since geology became a science. 
Many theories have been suggested to account for the sudden change of the 
climate of our planet, at the close of the tertiary age, from temperate and 
tropical heat to that of arctic cold. The theories put forth by the ablest 
