May 19, 1899.] 



SCIENCE. 



719 



SECTION OF GEOLOGY AND MINERALOGY, APRIL 

 17, 1899. 



Professor J. J. Stevenson in the Chair. 



Dr. A. A. Julien presented a ' Note on a 

 Feldspar from the Calumet Copper Mine, Ke- 

 weenaw Point, Michigan,' with specimens col- 

 lected by him at the first opening of that mine. 

 The wide distribution of the mineral was pointed 

 out, through both the Portage Lake and On- 

 tonagon districts, as drusy linings of cavities in 

 the amygdaloid and in crystals scattered through 

 the cement of the copper conglomerate. The 

 crystals were of simple type, a rhombic prism 

 with orthodome modification on obtuse angles, 

 but both faces and cleavage-planes were often 

 distinctly curved. By the complete analysis 

 presented, it was identified as a normal ortho- 

 clase, with an unusually large proportion of 

 protoxides in isomorphous replacement. These 

 seemed to bear a relationship to the instability 

 of the mineral, indicated by its general partial 

 decomposition ; to its remarkably low Specific 

 Gravity, 2.455; and possibly, in part, to the 

 curvature of its planes. 



Professor J. F. Kemp called attention to the 

 unusual presence of cobalt oxide in a feldspar, 

 shown in the analysis. 



Dr. E. O. Hovey then gave a very interest- 

 ing description, with lantern illustrations, of 

 ' Geological and Mineralogical Notes Gathered 

 during a Collecting Trip in Russia,' in connec- 

 tion with the excursions of the recent Interna- 

 tional Congress. Many of the lantern pictures 

 were beautifully colored ; they referred in part 

 to ethnographic observations ; and the accom- 

 panying remarks awakened much interest. 

 Alexis A. Julien, 

 Secretary of Section. 



geological conference and students' club 

 of harvard university. 

 Students^ Geological Club, March 28. — Mr. C. 

 H. White explained a method of field work that 

 has been developed by the members of the Ap- 

 palachian Division of the United States Geolog- 

 ical Survey. It can be used only in regions of 

 distinctly bedded rocks of low dip, and has the 

 merit of greatly facilitating both field and lab- 

 oratory work. Mr. A. W. Grabau exhibited a 



number of new paleontological specimens 

 which were collected by Mr. W. W. Dodge 

 from the middle Cambrian, at Braintree, Mass. 

 These included nine very perfect specimens of 

 a new species of Acrothele. 



Qeological Conference, April J^,, 1899. — In ' A 

 Comparison of Snow-chart with Ice-lobes,' Mr. 

 R. K. Kent described a method of comparing 

 the location of snow accumulations of the pres- 

 ent time with those of glacial time ; the posi- 

 tion of the former being indicated by snow- 

 charts and the latter by frontal moraines. From 

 these snow-charts, issued weekly by the 

 Weather Bureau, composite charts for the 

 winters of '96-' 97 and '98-' 99 were constructed. 

 These showed that the lines of equal snow- 

 averages follow lobations which in character 

 and position closely correspond to the glacial 

 lobes. The driftless area of Wisconsin was 

 thus shown to have been an area of minimum 

 snow-average, during the past winter. In their 

 tendency toward local retention, the distribu- 

 tions of snow for these two winters show in 

 miniature a remarkable likeness to the supposed 

 distribution of glacial times. 



In considering the causes of annual isochional 

 lobations, maps were shown which gave lines 

 indicating equal frequency of exposure of local 

 ai'eas to traversal by cyclonic areas during 

 these winters. These present a remarkable re- 

 semblance between these lines and the distribu- 

 tion of snow. Accordingly, the speaker con- 

 cluded that the lobations shown by the charted 

 averages are due to meteorological rather than 

 to topographical causes. 



Dr. R. A. Daly communicated the results of 

 a study of etch figures produced with hydro- 

 fluoric acid and the caustic alkalies on the 

 principal planes of the amphiboles, with espe- 

 cial reference to the cleavage prism. He sum- 

 marizes the chief problems which he studied in 

 this connection as follows: " (1) The orienta- 

 tion of the amphiboles — that of Tschermak 

 (Dana, Lacroix) is preferred to that of Norden- 

 skiold (Hintze) ; (2) the orientation of cleavage 

 pieces of amphiboles ; (3) the limits of variation 

 on (110), (010) and (100) of the different species 

 of amphibole — these can be used for determina- 

 tive purposes ; (4) the testing of Retgers' law 

 that isomorphous bodies must have, using the 



