Wadsworth. ] 470 [March 17 
bd 
General Meeting. March 17, 1880. 
The Prone Mr. T. T. Bouvé, in the chair. |Twenty- 
SIx persons present. 
The following gentlemen were elected Associate Mem- 
bers: Messrs. F. G. Darlington, Pittsburg, Pa.; Dr. H. C. 
Haven, Prof. Henry W. Haynes, W. G. Corthell, John Os- 
borne Sumner, Boston; and John H. Thurston, of Cam- 
bridge. 
The following paper was read : 
ON THE ORIGIN OF THE [RON ORES OF THE MARQUETTE Dis- 
TRICT, LAKE SupERIOR. By M. E. WapswortTua. 
However distant the Lake Superior district may seem to us, it is 
eminently fit that its geological problems should be discussed before 
this Society. The earlier explorers were largely members of this 
body, and questions relating to the geology, mineralogy, and physical 
geography of that most interesting region have been debated from 
time to time here. Of the members of this Society who have been 
more or less actively engaged in the exploration of the Lake Superior 
district, we may mention both Agassizs, Desor, Foster, Jackson, 
Marcou, Marvine, Pumpelly, the brothers Rogers, and Whitney; 
while on the pages of the Society’s publications over forty papers 
relating to the district can be found. 
One of the most important and interesting questions relating to 
Lake Superior geology is the question of the origin of the iron ores. 
It is important and interesting not only from a scientific point of 
view, but also from an economic standpoint. If it be asked how its 
origin can be determined, we reply that we believe that every geolog- 
ical formation, whether chemical, mechanical or eruptive, contains 
within itself and in its relations to other rocks, the story of its origin 
and subsequent history. This story is to be read with greater or less 
facility, according to the amount of obliteration subsequent changes 
have produced upon the marks left by the preceding events; also 
according to our knowledge of, and skill in reading, these charac- 
ters. It is necessary in such cases to proceed fon the known to’ 
the unknown. We are to study the structure and relations of rocks, 
