EEPORT OF THE SECRETARY. 5 



GEOLOGICAL EXPLORATIONS IN THE ROCKY MOUNTAINS. 



In continuation of my previous geological researches in the Rocky 

 Mountains of Canada and Montana I spent a week during the field 

 season of 1914 at Glacier, British Columbia, where I assisted Mrs. 

 Walcott (nee Mary M. Vaux) in measuring the flow of the Illecille- 

 waet and Asulkan Glaciers. 



From Glacier we proceeded to White Sulphur Springs, Mont., 

 for the purpose of studying the ancient sedimentary pre-Paleozoic 

 rocks of the Big Belt Mountains. These explorations were made on 

 the eastern and southern slopes of this range, and then extended to 

 the south on the Gallatin, Madison, and Jefferson Eivers. 



It was found that the pre-Paleozoic sedimentary rocks were ex- 

 posed by the uplift of the granite mass forming the summit of 

 Mount Edith of the Big Belt Mountains in such a way that the 

 thickness of the sandstones, limestones, and shales could be readily 

 measured in the numerous sections exposed in the canyons worn by 

 waters descending from the higher points to the valley surrounding 

 the range. Nearly 5 miles in thiclmess of rock were measured, and 

 in the limestone belts reefs of fossil algal remains were studied and 

 large collections made with the assistance of Mrs. Walcott and 

 Charles E. Eesser and sent on to Washington. 



It was found that the algal remains were deposited very much 

 in the same manner as those that are now being deposited in many 

 fresh-water lakes, and that many of the forms had a surprising simi- 

 larity to those being deposited in the thermal springs and pools of 

 the Yellowstone National Park. 



In the lower portion of Deep Creek Canyon, southeast of the city 

 of Helena, a deposit of siliceous shale was examined where some 

 years ago I had discovered the remains of crablike animals suggest- 

 ing in form the fresh-water crayfishes found in the streams and ponds 

 all over the world. These fossils are the oldest animal remains now 

 known, and the algal deposits which occur at intervals for several 

 thousand feet below the shales containing the crustaceans are the 

 oldest authentic vegetable remains. It is also most interesting that 

 two types of bacteria have been found in a fossil state in the rock 

 in association with the algal remains. 



On the north side of the Gallatin River two very rich beds of 

 algal remains were found, many of which, on account of the fossil 

 being silicified and embedded in a softer limestone, were weathered 

 out in relief. 



For the season of 1915 I have planned some investigations in the 

 Yellowstone Park in order to be able to better interpret the fossil 

 algal remains found in and about the Big Belt Mountains. 



