406 



SCIENCE 



[N. S. Vol. XXVII. No. 



Field Assay of Mine Waters: Alfred C. 



Lane, Lansing, Mich. 



The theory of ore deposition and circu- 

 lation by underground waters much needs 

 to be supplemented by tests and analysis 

 of mine waters. Some of the "field as- 

 say" methods are applicable, but the pres- 

 ence of calcium chloride makes the sodium 

 acid sulphate test for carbonates inap- 

 plicable. It is well to make a preliminary 

 test of the concentration of the water by 

 a hydrometer or by a specially devised 

 total reflectometer. In the stronger mine 

 waters it is often best to add the water to 

 a solution of the reagent. 



The following papers were read by title : 



The Phosphate Deposits of Florida with 

 Relation to the Underground Water 

 Level: E. H. Sellakds, Tallahassee, Fla. 



Asiestos Deposits of the Grand Canyon, 

 Arizona: Joseph Hyde Pratt, Chapel 

 Hill, N. C. 



Ancient Tectonics of the Basin Ranges: 

 Charles R. Kbtes, Des Moines, la. 



Rock-flora of Intermont Plains of Arid 

 Regions: Charles R. Kbyes, Des Moines, 

 la. 

 The next paper read was 



Glacial Periods and their Bearing on Geo- 

 logical Theories: A. P. Coleman, To- 

 ronto, Can. 



Four well-defined glacial periods are 

 known in geological history, occurring in 

 the Pleistocene, the Penno-Carboniferous, 

 the lower Cambrian and the lower Huron- 

 ian, final proofs of the last-named glacial 

 period having been obtained only recently. 

 The wide distribution of glacial deposits 

 in at least three of these periods proves 

 that refrigeration was general and included 

 both hemispheres. There is evidence of 

 important interglacial periods in three of 

 the ice ages. The importance of these 



facts as bearing on the origin and early 

 history of the earth and on the factors 

 which cause variations of climate was 

 pointed out. 



An active discussion was participated in 

 by W. G. Tight, A. C. Lawson, I. C. White, 

 H. M. Ami, G. K. Gilbert, H. E. Gregory 

 and C. R. Van Hise. 



The Chief Features of the Stratigraphy 

 and Structure of Mount Diablo, Cali- 

 fornia: George D. Loxjderback, Berke- 

 ley, Cal. 



Mount Diablo is a distinctive feature of 

 the central coast ranges because it rises 

 from low valleys on practically all sides 

 and is not merely a more prominent peak 

 of a continuous range. It shows a remark- 

 ably complete stratigraphic series of the 

 characteristic Coast Range formations. 

 Structurally it is an overturned and over- 

 thrust anticline of very late origin. There 

 is also evidence of an earlier structural 

 form. The geology of Mount Diablo may 

 be taken as showing a stratigraphic succes- 

 sion and an orogenic history characteristic 

 of the coast ranges from the Klamath 

 Mountains to the Tehachapi. 



The paper was discussed by A. C. Lane, 

 A. C. Lawson and H. P. Cushing. 



The following papers were then read by 

 title : 



The Earthquake in Owens Y alley, Cali- 

 fornia, in 1872: WiLLLiM Herbert 

 HOBBS, Ann Arbor, Mich. 



Beginning and Recession of Saint An- 

 thony Falls: Frederick W. Sardeson, 

 Minneapolis, Minn. 



The "Nehraska Loess Man": B. Shimek, 

 Iowa City, Iowa. 



The Distribution of Drumlins and its 

 Bearing on their Origin: Frank. B. 

 Taylor, Fort Wayne, Ind. 



