LIBRARY 
OF THE 
UNIVERSITY Of ILLINOIS 
o. 
THE 
AMERICAN GEOLOGIST. 
Vol. XX. DECEMBER, 1897. No. 
GEOLOGY OF THE ST. CROIX DALLES.* 
By Charles P. Beekey, Minneapolis. 
[nt rod action. 
The area described in this paper covers sixty square miles. 
It is ten miles long, north and south, and six miles wide. The 
St. Croix river flows through the district from north to south, 
dividing it into two unequal tracts. The portion on the west 
side of the river, comprising approximately twenty square 
miles, lies within the state of Minnesota; the eastern portion, 
approximately forty square miles in extent, belongs to the 
state of Wisconsin. The meridian of 92*^ 40' longitude west 
from Greenwich and the parallel of 45^ 25 ' north latitude, 
pass through the district. The north line of town 34 forms 
the northern boundary, and the line between ranges 18 and 19 
west of the fourth principal meridian passes lengthwise 
through the middle of the area. The villages of Taylor's Falls 
in Minnesota, and St. Croix Falls in Wisconsin, are centrally 
situated. 
The southwestern extension of the Keweenawan copper- 
bearing rocks presents numerous outcrops at this point, and 
their erosion by the St. Croix river forms the well-known 
" Dalles of the St. Croix." On account of this prominent nat- 
ural feature, the district has been called the St. Croix Dalles 
Area. 
*A thesis accepted by the faculty of the University of Minnesota for 
the degree of Doctor of Philosophy, June, 1897. 
