32 ANNUAL REPORT OF THE 



REPORT ON THE GEOLOGICAL COLLECTIONS. 



By R. W. Sayles. 



The installation of the unique collection of cave deposits from 

 Bisbee, Arizona, in the new hall case, was successfully accom- 

 plished. The dark hall and artificial lighting give a realistic effect 

 not attainable by sunlight. 



In January, the Curator studied the collection of microscopic 

 slides of slate and shale at the National Museum in Washington, 

 with the object of finding evidences of seasonal deposition. This 

 search resulted in the discovery of probable seasonal banding in 

 lowest Cambrian or latest Proterozoic times. In June, Mr. Allyn 

 C. Swinnerton, a graduate student, was sent to collect specimens 

 and make a field study of some of the slates examined in Washing- 

 ton. His findings corroborated the microscopic evidence noted 

 in the slides. Mr. Swinnerton visited several localities in south- 

 east Tennessee, in New York near Albany, and in western Vermont, 

 and the Cobalt, Ontario, region. The Curator takes this oppor- 

 tunity to express his gratitude to the geologists at Washington for 

 the willing help given him. 



The months of February, March, and April, were spent in study- 

 ing the literature bearing on geologic climates. 



Mr. Preston E. James gave a splendid slab of glaciated granite 

 from Rockport, Mass. The labels in the Museum have been 

 renewed. 



