F" 



Proceedings. 185 



series in which has been brought to light latterly a wonderful fauna of 

 primordial life, and which extends from the Atlantic slopes to the western 

 basis of the Rocky mountains. This overlap unconformity implies a sink- 

 ing of the pre-existing land, and of the ocean's bed, bringing the later 

 formed strata over the beach-limit that existed before. 



We may conclude therefore that the observations that were made on 

 the recent excursions conform, at least do not contravene, the views lately 

 set forth by Irving, Bonney and Lawson, and the conclusions published by 

 the reports of the Minnesota survey, to the effect that the Huronian system 

 as now defined and understood by the Canadian geological reports, really 

 embraces two or three formations; that one of these is the true Huronian,. 

 as at first discribed and mapped by Murray, another is the Keewatin of Dr. 

 A. C. Lawson, containing the iron ores at Tower, Minnesota, and another is 

 the series of crystalline schists which we have styled Vermillion series. In 

 other places these three formations have been fully treated.* They are dis- 

 tinctly separate by lithology and by unconformities that have been noted 

 from Vermont to Minnesota, and should no longer be included under a 

 single term, at least not under the term Huronian, which at first had a cor- 

 rect and adequate definition embracing but one of them. 



Horace V. Wincliell read a paper on " The Iron-ore bearing^ 

 rocks of Minnesota." [See paper FF.] 



L. W. Chaney, Jr., presented '' some notes on the Cryptozoon 

 Minnesotense Winehell of the Cambrian rocks of Minnesota, par- 

 ticularly those in the vicinity of Northfield." [See paper GG.] 



Warren Upham read a paper describing a recent visit to Lake 

 Itasca. [See paper HH.] 



December 3, 1889. 



Ten persons present. 



The following persons v^^ere elected members: Jos. R. Hofflin^ 

 Henry Howling, Minneapolis; W. H. Scofield, Cannon Falls. 



The amendment to the by-laws proposed at the October meet- 

 ing, to-wit: to change Article vii, Section 1, by striking out the- 

 words "resident in the state," was presented and carried.f 



C. W. Hall gave an account of "a vacation trip into the Black 



Hills of South Dakota." 



[abstract.] 



The excursion was made in company with Professor Van Hise of the 

 U. S. Geological Survey, who was making a summer's reconnaissance through 

 certain Archaean areas of the western half of the United States. The Pro- 

 fessor's object in visiting the Black Hills of South Dakota was to determine 



*See the seventeenth annual report, Minnesota survey. 



fPor the constitution and by-laws of the Academy see Bulletins, Vol. ii, pp. 1 to 

 6, incl. 



