Proceedings. 41 



climatic conditions, particularly in temperature and rainfall between two 

 contiguous districts of the state, viz., the area drained by the Mississippi 

 river from Fort Snelling northward, amounting to 16,596 sq. mi. and the 

 area drained by the Minnesota river amounting to 15,706 sq. mi. These 

 two districts have the following points in common ; first, they differ only 

 about 900 square miles in area; second, they are uniformly level or slightly 

 rolling in surface contour; third, they have about the same elevation 

 above the sea, viz., 1200 or 1300 feet ; They differ but little in latitude and 

 loagitude since boundary between them is an irregular northeast and 

 southwest line. They have the following points of difference; first, the 

 Mississippi does not shed a great deal more water per annum than does 

 the Minnesota; second, Mississippi is largely forest covered while the 

 Minnesota is largely one of prairie. Tongues of forest extend into the 

 Minnesota area as patches of prairie are here and there found in the Mis- 

 sissippi area ; third, the amount of river drainage from these two areas 

 could easily be determined by measuring the outflow of the two streams at 

 Fort Snelling where they unite. The temperature, the moisture of the air, 

 the annual rainfall and other conditions can easily be determined through 

 a series of observation stations. Some efforts were made several years ago 

 by the speaker to secure the necessary data but they were unavoidably 

 interrupted. 



Mr. A. E. Elftman then read a paper entitled, ''Notes on 

 the geology of the Greenwood lake area." 



This area is one that Mr. Elftman studied under the direction of the 

 State Geologist of Minnesota during the field season of 1893. The paper # 

 was briefly discussed hkr Mr. Upham, Dr. Grant, and others. 



riarch 13, 1894. 



President Osborn in the chair. 

 Twenty members present. 

 The following papers were presented : 

 Differentiation of igneous magmas, U. S. Grant. 

 An abandoned post-glacial valley of the Saint Louis 

 river, J. E. Spurr. 



Mr. Spurr's paper was illustrated by some maps and drawings show- 

 ing the position of this valley and its relation to the accumulation of 

 glacial debris along its borders. 



"Departure of the ice-sheet from the basin of Lake Super- 

 ior," Warren Upham. 



This was illustrated by maps and diagrams especially of the glaciation 

 and accumulation of glacial debris in the vicinity of Duluth. 



