ABSTRACTS OF PAPERS 97 



NEW TEACHING DIAGRAM FOR IGNEOUS ROCKS 

 BY A. B. VAN ESBROECK ^ 



Eead by title. 



AEROLITE FROM ROSE CITY. MICHIGAN 

 BY EDMUND OTIS HOVEY 



(Abstract) 



A meteorite was seen to fall at 11 o'clock a. m. October 17, 1921, near Rose 

 City, Ogemaw County, Michigan. Its path through the sky was from north- 

 northwest to south-southeast. Three explosions were heard, but only three 

 fragments, weighing together about 10,376 grams, have thus far been recov- 

 ered. The mass is composed of 17.25 per cent nickel iron and 82.75 per cent 

 mineral matter, principally enstatite and olivine, with some anorthite. The 

 structure is achondritic and agglomeratic. The chief additional feature of 

 interest is the presence of abundant small miarolitic cavities in the mass, 

 which are lined with minute crystals which seem to be of enstatite and olivine. 

 Specific gravity of the finely pulverized material, 3.694. 



Presented in abstract extemporaneonsly. 



ORIGIN AND FORMATION OF CERTAIN APPALACHIAN BAUXITE DEPOSITS 



BY WILBUR A, NELSON 



Read in full from manuscript. 



Brief remarks were made by Messrs. Bonine and Lane. 



STORMBERG LAVAS OF SOUTH AFRICA 

 BY FRED. E. WRIGHT 



{Abstract) 



The Stormberg basaltic lavas of South Africa, like the Deccan traps of India, 

 the Snake River basalts of our Western States and of Patagonia, are of the 

 so-called fissure eruption type and cover vast areas. The Stormberg region 

 has been partly mapped geologically and topographically by Dr. A. L. du Toit. 

 It was the writer's good fortune to spend several weeks last July with Dr. du 

 Toit in a field study of the Stormberg lavas with reference especially to the 

 conditions of their eruption. The lavas are of Jurassic age and form great, 

 nearly horizontal sheets, each flow maintaining throughout about the same 

 characteristics and thickness. The total thickness of the series is approxi- 

 mately a mile ; the average thickness of a single flow is about 22 feet. Field 

 evidence indicates that the lavas were highly liquid when they flowed over the 

 land surface, that volcanic gases played a role less obviously important than 

 in ordinary eruptions of the central cone type. To solve the problems involved 

 in -fissure eruptions, both field and laboratory work are essential if an even 



^ Introduced by James F. Kemp. 



VII — Bull. Geol. Soc. Am., Vol. 34, 1922 



