Geology of the St. (Jroix Dulles. — Berkeij. 363 
The facts suggest tlie following statement of conditions ob- 
taining during and immediately preceding the withdrawal of 
the latest glacial ice lobes at this locality. The western ice 
lobe advanced spreading the western drift to the very position 
now occupied by the central plain. Here it was met and en- 
ergetically opposed by a northeast lobe carr^nng much debris 
and rapid!}' accumulating the thicker eastern drift deposits. 
The eastern advance was even energetic enough to override 
the edge of the western lobe, and left a few patches of char- 
acteristic material within western territory. With the melt- 
ing of the ice the two lobes separated and a lake formed on 
the present site of the plain, which was drained by the devel- 
opment of the channel at its southern extremity. 
An early halt in the eastern lobe developed the St. Croix 
moraine and served to furnish immense floods to the rivers of 
that time, of wiiich there are traces of at least two more with- 
in the district. As the western lobe retired it uncovered an 
additional line of drainage represented by the present river 
gorge and the narrow valle}'' extending northward along the 
railroad to St. Croix Falls station. 
The level floor of this narrow erosion vallej' for a distance 
of at least a quarter of a mile indicates that at this elevation, 
905 feet, deeper water was reached, which eflfectually checked 
extensive erosion. 
It is important to note in this connection that the Taylor's 
Falls picnic grounds bench across the river is of the same el- 
evation, and equally level, and equally suggestive in the char- 
acter of its material of river or lake influence. If it be river 
influence, they mark the highest prominent river terrace ; if it 
indicate the position of an ice-dammed lake, the fact still re- 
mains that such a lake occupied the place of the later river, 
and upon its subsequent drainage left, as its eastern and west- 
ern limits, these two terrace-like deposits in evidence of its 
existence. 
The central plain just described is intimately connected 
with a more extensive tract which may be referred to as the 
Dresser Junction flood plain. 
The rock bound gorge connecting these two plains is clear- 
ly a glacial river channel. It broadens into a sand covered 
valley at an elevation of 9(35 feet, following closely the west 
