THE 
. American Geologist 
A MONTHLY JOURNAL OF GEOLOGY 
AND 
ALLIED SCIENCES 
EDITORS AND PROPRIETORS 
Samuel Calvin, Iowa City, Iowa. 
John M. Clarke, Albany, N. Y. 
Edward W. Claypole, Akron, Ohio. 
Francis W. Cragin, Colorado Springs, Colo. Robert T. Hill, Austin, Texas. 
John Everman, Easton, Pa. Joseph B. Tyrrell, Ottawa, Out. 
Persifor Frazer, Philadelphia, Pa. Edward O. Ulrich, Newport, A r 
Warren Upham, Somerville, Mass. 
Israel C. White, Morgantown, IV. Va . 
Newton H. Winchell, Minneapolis, Minn. 
VOLUME XII. 
July to December, 1893. 
Minneapolis, Minn. 
The Geological Publishing Company. 
1893/ 
ALFRED Roper, Printer. 
