Geology of Ihe St. Croix Dalles. — Berhey. 3(51 
raine are largely sand, gravel and small boulders, and the 
origin is the same as is that of the red drift. 
The Level Tracts. Three well developed plains covered 
mostly with till, occur partly within and partly without the 
St. Croix Dalles area. Tliese will he referred to as the eastern, 
western and central plains. 
'The eastern plain extends from the St. Croix moraine east- 
ward for several miles. Onl}'^ a narrow strip comes within the 
territory examined, but enough of it has been seen to disclose 
its prevailing characters. It is rolling or undulating in sur- 
face, but does not vary much from the 1,200 foot elevation. 
There are numerous small lakes and sloughs, and it is an area 
of excellent farming land, thickly settled. Its material is a 
till with characters which belong to the eastern drift. 
The western plain lies upon the west side of the St. Croix 
river. It extends from Franconia station westward and north- 
ward, including the whole west central portion of the district. 
The northeastern boundary is formed by the diabase ridge 
extending from the village of Taj'lor's Falls northward. This 
plain also extends far beyond the bounds of the area. Only 
occasional irregularities break the prevailingly level contour, 
varying in elevation from 915 feet at Franconia to 950 feet a 
few miles further north. It is a till covered area of western 
drift, the character of which can be studied in many places. 
The drift on this area* has been noted and approximateh'^ 
mapped by Mr. Upham. 
The prominent bench in the village of Taylor's F'alls, known 
as the picnic grounds, is in character of materials intimately 
connected with the western till plain. The considerable ac- 
cumulation of sand and other modified drift bounding it on 
the west does not apparently owe its origin wholly to river 
action; it is no doubt derived from the adjacent esker-like 
ridge. 
The central plain is a peculiar glacial accumulation situated 
immediately to the east of the village of St. Croix Falls. It 
occupies a large part of the S. E. ^, Sec. 19, and a portion of 
See. 20 adjacent, the N. E. ^ of Sec. 30 and the adjacent por- 
tion of Sec. 29, T. 34 N., R. 18 W. This accumulation is con- 
*GpoI. and Nat. Hist. Survey of Minn., Final Reijort, vol. ir, 1888. n 
412. 
