Geology of the St. Croix Dalles. — Berkey. 375 
of the hill as the street approaches the public school building. Other 
localities where contact of the Cambrian strata and the Keweenawan is 
marked by a conglomeratic tendency are: — At the river bank, St. 
Croix Falls, and at the test pit in N. W. ^4, S. W. 14, N. E. 1|, Sec. 1, 
T. 33 N., R. 19 W., near the highway, three eighths of a mile S. W. of 
the sandstone conglomerate outcrop. 
At none of these places, however, is there any such extensive expos- 
ure as at the first two named. 
The lirst mentioned locality is a prominent landmark on 
the river between Franconia and Osceola.* A narrow ridge 
runs out from the main river blutf squarely to the stream, 
where the vertical face, 40 feet in hight, reveals the cause of 
its successful resistance to the erosion which h;is worn back 
the sandstone blutf several rods. There is at this place an 
apparent absence of the rocks from which this conglomerate 
could have been derived. No outcrop of these rocks is to be 
seen on the same side of the river, although it is possible that 
the adjacent higher river blutf* encloses or covers such a ledge. 
That this conglomerate has outlasted the parent cliff beside 
which it must have been formed seems to be a necessary con- 
clusion. There is, however, an almost unbroken ridge of dia- 
base extending from the railroad, two miles north of Dresser 
Junction to the river just opposite the conglomerate exposure 
and no doubt at one time was connected with it. River eros- 
ion has destroyed all connection which once existed between 
the two and which still may exist beneath the bed of the 
river. In such a way, indeed, an adjacent cliff may have been 
destroj'^ed while favorable conditions saved a part of the con- 
glomerate beside it. 
The same fossil species occur in this conglomerate as are 
found in the adjacent shales. It belongs to the upper bed, 
the green shales, of the Dresbach formation. 
Two outcrops of conglomerate on Mill street in Taylor's 
Falls, are probably continuous beneath the drift. Their 
marked differences in color, hardness, and compactness of the 
matrix are not of great taxonomic importance. The exposure 
at the brow of the hill is near the 875-foot contour line, and 
for convenience of reference will be called the upper conglom- 
erate. The one at the railroad crossing is at about the 810- 
*Owen: Geol. Survey of Wis., Iowa and Minn., 1852. 
Section 4, from Marine Mills to the falls of St. Croix. 
N. H. Winchell: Tenth annual report, Minnesota survey, 1881, p. 120. 
