Proceedings. 27 



Keweenaw series is made up of silicate sands. A marked distortion of strata 

 occurs along the line of junction between the two formations; the beds are 

 bent up usually, exceptionally down, along this junction and there is a line 

 of junction debris partly trappean and partly of detrital material, with con- 

 tact faces, slickensides and foliated structure. 



From these and other specification, the conclusion is reached by the 

 authors "that the Keweenaw series is much older than the Eastern (Potsdam) 

 sandstone; that it was upturned, faulted along the escarpment and much 

 eroded before the deposition of the Eastern sandstone; that the latter was 

 laid down unconformably against and upon the former and that subsequent- 

 ly minor faulting along the old line ensued, disturbing the contact edge of 

 the sandstone." [Page 106.] The Trenton limestone and possibly other forma- 

 tions were subsequently laid down to be removed again at a still more recent 

 date. 



April 6, 1886. 



Three persons present . 



The evening after the city elections and no quorum. 



May 4, 1886. 



Sixteen persons present. 



F. L. Washburn read a paper prepared by Mr. N. Kolkin for 

 the Academy entitled, "the effect of an electric current on the 

 oscillation of suspended bodies. 



The secretary read for Mr. John Leiberg, ''some notes on the 

 most recent fossil flora of North Dakota and an inquiry into the 

 causes that have led to the development of the treeless area of the 

 Northwest." [See paper U.] 



A paper by Warren Upham was read giving ''a description 

 for a set of maps showing the climate, geography and geology of 

 Minnesota." [See paper V.] 



The Secretary C. W. Hall gave the Academy an account of 

 the tornado which visited St. Cloud in A.pril last. [See paper W.] 



June 8, 1886. 



Seventeen persons present. 



Miss Gertrude J. Leonard was elected a member. 



Professor L. W. Chaney, Jr., from the section of invertebrate 

 zoology discussed *'the anatomy and embryology of Unio^'' era- 

 bodying the professor's laboratory notes and studies so far as he 

 had been able to pursue them in a single season. 



Mr. F. L. Washburn gave an account of the method employ- 

 ed on the U. S. Fish Commission's Steamer Albatross in securing 

 marine invertebrates, with incidental mention of the character and 

 outfit of the vessel. 



