January 20, 1899.] 



SCIENCE. 



101 



the eleventh annual meeting at Columbia 

 Uuiversit}', December 2Sth. Just nine years 

 had elapsed since its last session in New 

 York, which was held at the American 

 Museum of Natural History. The Society 

 assembled this year at 10 a. m., on Wed- 

 nesday, the 2Sth, in the large lecture room 

 of Schermerhorn Hall ; Professor J. J. Ste- 

 venson, the retiring President, in the chair. 

 President Low was introduced and in a few 

 happily chosen remarks welcomed the So- 

 ciety to Columbia. After the usual routine 

 business, President Stevenson read a me- 

 morial of the late Professor James Hall, so 

 long State Geologist of New York and the 

 first President of the Society. At the con- 

 clusion of the memorial Professor Steven- 

 son delivered his presidential address upon 

 the subject ' Our Society.' He sketched the 

 rise and development of geological organiza- 

 tions in North America and discussed the 

 important influence that they have exercised 

 in the material progress of the country. 

 The address appeared in full in the last 

 number of Science. 



The reading of papers was at once begun, 

 as a list of fifty titles had accumulated. 



The Archcean- Potsdam Contact in the Vicinity 

 of Manitou, Colorado. W. O. Crosby, Bos- 

 ton, Mass. 



The speaker described the remarkably 

 plane character of the contact of the Ar- 

 chsean granite and Potsdam sandstone, 

 which is in striking contrast with the exist- 

 ing topography of the granite even in 

 coastal regions. He distinguished and de- 

 scribed in detail, with numerous illustra- 

 tions, the original and secondary irregular- 

 ities, the latter including a few flexures 

 and numerous small faults which throw 

 important light upon the origin of the sand- 

 stone dikes of the Manitou district. The 

 original irregularities of the contact are all 

 small, and, as a rule, are evident! j' related 

 to tlie existence in the Archajan granite of 



a coarse concentric or spheroidal structure- 

 The plane type of erosion-unconformity, 

 although probably of rather widespread and 

 common occurrence, appears to liave at- 

 tracted less attention than it merits. It 

 suggests interesting possibilities as regards 

 the development of peneplain surfaces in 

 early times and invites a renewed com- 

 parison of the relative efficiency in base- 

 leveling of subaerial and marine agencies. 

 These more theoretical aspects of the sub- 

 ject were embraced within the scope of the 

 paper, and the general conclusion was that 

 the Archtean land surface must have passed 

 with extreme slowness beneath the waves 

 of the Potsdam sea. 



The paper was illustrated with maps and 

 lantern slides and excited great interest, but 

 did not arouse discussion. 



Outline of the Geology of Hudson's Bay and 

 Strait. Robert Bell, Ottawa, Canada. 

 The author described the general nature 

 of the depression of Hudson's Bay ; the 

 contrasted characters of the opposite shores; 

 the Huronian areas on both sides ; the In- 

 termediate Formation ; the Animikie and 

 Nipigon series ; the Trenton gi-oup in Hud- 

 son's Bay and Strait ; the middle Silurian 

 rocks on the east, west and north sides 

 of the Bay and in Baifinland ; the large 

 Devonian area southwest of James Baj' ; 

 the Devonian rocks on Southampton Is- 

 land ; and the geology of the islands in the 

 Bay. He gave a general geological descrip- 

 tion of Hudson's Strait and of the rocks of 

 its north shore, or southern Baffinlaud. He 

 also took up the Laurentiau and older 

 Cambrian strata of the Ungava district. 

 Under the head of the economic minerals 

 of the regions described, some details of the 

 rich iron-ore deposits, involving carbonates, 

 hematites and magnetites, were presented. 

 In connection with the glacial geology of 

 Hudson's Bay and Strait he sought to show 

 the source of the ice that had yielded the 



