January 26, 1900.] 



SCIENCE. 



145 



tion, and Dr. Washingtou's study of the 

 Magnet Cove area leads him to believe that 

 the soda-rich rock species abounding here 

 are simply highly differentiated products 

 of the same continuous flow, and not of 

 three different periods of eruption, as was 

 thought by Dr. Williams. Six analyses 

 were shown which exhibited such a regular 

 variation in the percentages of the various 

 oxides, that the inference was strong to- 

 wards magmatic differentiation. The cen- 

 tral mass is a basic ij elite with low silica 

 36.51 per cent., and high calcium oxide and 

 the surrounding more or less concentric 

 masses increase their acidity giving, on the 

 outer band a nepheline syenite with silica 

 63.38 per cent, and large increase in alka- 

 lies and low lime. These successive bands 

 show abnormal arrangement. 



Plagioclase is absent from the rocks. The 

 abundant garnet is accounted for through 

 the excess of lime, as shown in the analyses. 



The time was too short to allow the 

 speaker to dwell much upon the dikes, or 

 upon the reason for calling the mass a lac- 

 colite. 



The final paper was then presented by 

 August F. Foerste on ' Further Studies on 

 the History of the Cincinnati Anticline. ' 

 The theory held by former investigators that 

 the age of this anticline is Lower Silurian 

 and that the Upper Silurian strata were de- 

 posited during the gradual subsidence of 

 the central mass, is untenable as shown by 

 measurements of the adjacent strata. Ac- 

 cording to this theory the upper or last 

 formed deposits would extend farther up 

 the sides of the anticline, whereas careful 

 measurements show that the lowest forma- 

 tions extend the greatest distance up the 

 sides, and Mr. Foerste's theory is that these 

 deposits at one time were continuous across 

 the present anticline and on account of 

 flexure and erosion now occupy the sides, 

 thus indicating an age for the anticline later 

 than the Upper Silurian. 



Mr. Campbell agreed with the speaker 

 that there was no evidence of Lower Silurian 

 age for the anticline. 



The following papers were then read by 

 title by the President : 



BBCONNATSSANOB IN SOUTHEASTERN ARIZONA. 



E. T. DuMBLE, La Barranca, Mexico. 



ON THE AGE AND DISTRIBUTION OF THE SEDI- 

 MENTARY ROCKS OF PATAGONIA. 



J. B. Hatcher, Princeton, N. J. 



CRETACEOUS INVERTEBRATES FROM PATAGONIA 

 COLLECTED BY J. B. HATCHER. 



T. "W. Stanton, Washington, D. C. 



GEOLOGY OF THE WICHITA MOUNTAINS. 



H. Foster Bain, Des Moines, Iowa. 



VOLOANICS OF THE NEPONSET VALLEY, 

 BOSTON BASIN. 



F. Bascom, Bryn Mawr, Penna. 



ENRICHMENT OF MINERAL VEINS BY LATER 

 METALLIC SULPHIDES. 



Walter Harvey Weed, Washington, D. C. 



VEIN formation AT BOULDER HOT SPRINGS, 

 MONTANA. 



Walter Harvey Weed, Washington, D. C. 



GENESIS OF THE LIMONITE ORES OF PENN- 

 SYLVANIA. 



T. C. Hopkins, University of Chicago. 



CONTACT METAMORPHISM OF A BASIC IGNEOUS 

 EOCK. 



U. S. Grant, Evanston, 111. 



GEOLOGICAL STRUCTURE OF COFFEYVILLE 

 (KANSAS) GAS FIELD. 



G. Perry Grimsley, Topeka, Kan. 



SURFACE temperature OF THE EARTH. 



Alfred C. Lane, Lansing, Mich. 



THE GLACIATION OF MOUNT KTAADN, MAINE. 



Ralph S. Tarr, Ithaca, N. Y. 



POST-GLACIAL TIME IN HURON COUNTY, 

 MICHIGAN. 



Alfred C. Lane, Lansing, Mich. 



