Geoloiiy of the St. Croix Dalles. — Berkey. 857 
position, also further north, idong the high diabase ridge, 
there is a much more complicated succession. The most com- 
plete section is shown at the picnic ground, in Taylor's Falls, 
and on the side of the drift ridge back of the village. 
Upon the lower shales, at an elevation of 770 feet (see fig. 
2, plate XXII), rests partially stratified till of characteristicallj' 
eastern material, which continues uninterruptedly along the 
ravine, at the side of the street, to an elevation of 845 feet. 
At the same time the shales are traceable in the same ravine 
to an elevation from 800 to 825 feet, and then become con- 
cealed beneath the debris. A bed of gravel and small boulders 
about 2 to .3 feet in thickness lies immediately upon this red 
stratified deposit and separates it from the overlying accu- 
mulation of typical western bluish gray material. This west- 
ern drift is a till in which boulders, pebbles, gravel, sand and 
clay are promiscuously intermingled, and in which, compared 
with the lower member, regarded as eastern drift, the presence 
of numerous limestone boulders and an abundance of calcare- 
ous material is the most conspicuous feature. This upper 
member is not so markedly stratified as is the lower one. On 
the exposed surface, however, it has a tolerably compact ap- 
pearance due to the great amount of calcareous material 
available as a cementing substance. The result is, in some 
places, a kind of crag. The thickness of this gray and bluish 
gray drift layer is 35 to 40 feet, reaching an elevation of 885 
feet. From this point the character of the material changes 
somewhat, becoming chiefly sand and gravel with a covering 
of soil to the top of the blutf, at an altitude of 905 feet. This 
forms the highest river terrace, which continues westward as 
a sandy plain for a thousand feet, to the high ridge back of 
the village. Here, at an elevation of 935 feet, ten hundred 
and fifty feet east of the Swedish church, a large patch of red 
till 10 feet in thickness is found exposed. Above this there 
is sand and gravel to the highest, or 1,100 foot contour line. 
This red patch is believed to represent a later advance of the 
eastern ice lobe upon the western drift area, rather than a 
remnant of an earlier accumulation left unmolested bj"^ the 
western invasion. Additional support is given to this view by 
a similar exposure of red till occurring on the same ridge 
farther north, in the S. E. |, S. W. i, Sec. 13, T. 34 N., R. 19 
