

PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



GEOLOGICAL SOCIETY OF WASHINGTON 



The 254th meeting was held in the Cosmos Club March 13, 1912, 

 President Stanton being in the chair. The following informal communi- 

 cations were presented : 



Mr. David White brought up the question of the formation of lime- 

 stone near tide level thru the agency of calcareous algae and called 

 attention to the very important as well as striking data on the subject 

 published in the 18th part of the "Siboga-Expeditie," and to the work 

 of Rothpletz and other paleontologists on limestones of various ages in 

 Europe. Expressing the opinion that many of the limestones of the 

 American coalfields were formed very close to tide level and under cli- 

 matic conditions shown by the associated land plants to be favorable 

 for great development of coralline algae, the speaker hoped that this 

 branch of paleontology, almost untouched in America, might engage the 

 interest of some of our young paleontologists. 



Mr. K. D. Burling described the reexamination by Mr. J. A. Allan and 

 himself of the Mount Bosworth (British Columbia) section described by 

 Dr. Charles D. Walcott in 1908, in an attempt to determine the position 

 in that section of a series of 2500 feet of Cambrian shales and limestones 

 measured by Mr. Allan in the Ice River Region, and announced the find- 

 ing of typical Upper Cambrian (Sherbrooke) fossils in the "Ordovician" 

 beds forming the top of the exposed section, a discovery which enabled 

 them to place the Ice River beds in the interval between the Sherbrooke 

 and the true Ordovician. 



Mr. F. E. Matthes briefly called attention to the introduction by 

 French topographers of two new terms, " topology" and "topometry," 

 expressing concepts related to that of "topography," but different from 

 it. He gave the definitions, as laid down by Berthaut, and discussed 

 the desirability of the wider adoption of these terms, and the value of the 

 more precise differentiation between the respective concepts which would 

 ensue. 



REGULAR PROGRAM 



The development of a typical bolson in the Southwest: O. E. Meinzer. 

 The Spanish term "bolson," is used to designate constructional detritus 

 plains occupying structural troughs in arid regions. A good example of 

 a plain of this type is afforded by Sulphur Springs Valley in southeastern 

 Arizona. The northern part of this valley is a completely closed bol- 



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