352 The American Geologist. December, 1897 
It extends slightly beyond these bounds at several places, but not to a 
considerable distance. The valley is entirely rock-bound, the erosion of 
which was checked at the 800-foot line. This abandoned channel is in 
places an eighth of a mile wide. Moses Strong mentions this depres- 
sion* as probably an abandoned channel of the river St. Croix. There 
were two prominent rocky islands between it and the main channel at 
this stage. The first is now represented by the cliff south of the elbow, 
and the other is the prominent rocky hill in the middle of the S. % "^ 
Sec. 36, T. 34 N., R. 19 W. This channel marks the stage correspond- 
ing to the 810-foot terrace. 
4. As the river cut its way into the rocks and sank below the level of 
the last named channel, the water plunging through the gap at the el- 
bow formed a great whirlijool more than an eighth of a mile in diame- 
ter, which is still marked by the great bowl at the head cif Thaxter lake 
in N. W. }-i Sec. 31, T. 34 N., R. 18 W. The water froin this whirlpool 
reached the main river again by way of the broad, easy channel, the 
fourth in the series of river channels, the course of which is now 
occupied by the river-lake, Thaxter, lying chiefly in N. E. I4 Sec. 36, 
T. 34 N., R. 19 W. This, with the exception of the pot holes of the 
Dalles, is the most striking feature of the St. Croix river erosion. 
5. The river-lakes lying immediately in contact with the river from 
Sec. 11 to Sec. 22 of T. 33 N., R. 19 W., represent a part of the 
channel of the older St. Croix river, which is now almost wholly aban- 
doned . 
6. There is a well marked, although not a deeply or evenly eroded 
valley, extending through sections 1, 12, 11, 14 and 23 of T. 33 N., R. 19 
W., passing beyond the limits of the district and terminating in the 
very prominent abandoned gorge which separates the picnic ground and 
Eagle Point from the main river channel at Osceola. It is almost con- 
tinuously divided from the present river gorge by a ridge from 20 to 75 
feet high. The average elevation of the floor of this valley is 850 feet. 
This possibly represents an abandoned channel of the St. Croix at an 
early stage and probably during the time of a local glacial readjustment. 
Its persistence, almost parallel with the river for a distance of more 
than five miles, is the greatest evidence presented in favor of regarding 
it as an abandoned channel. It marks a stage corresponding to the 
development of the highest terrace noted near Stillwater, and the 905- 
foot terrace at Taylor's Falls commonly known as the picnic ground: 
and its later history, represented by the entire abandonment of that 
channel, is still marked by the 865-foot terrace of Upham.t 
River Temtces. There are five river terraces within the 
boundaries of this district, marking stages in the erosion of 
the St. Croix valley. They are all well marked within the 
two villages, St. Croix Falls and Taylor's Falls. These ter- 
races have been determined by various readings as : 
*Geology of Wisconsin, vol. Ill, 1880, p. 416. 
tGeol. and Nat. Hist. Surv. of Minn., Final Rep. vol. II., 1888, p. 417. 
