Origin of the Dells of the Wisconsin. 559 
North of the rock is a narrow swifter channel, which it is be¬ 
lieved has been produced by the intersection of two short dells 
developing along joints. 
Whether the Wisconsin itself through the dells, except along 
the narrows, can be considered to be controlled by joints is un¬ 
certain. This stream is so large and powerful that it has well 
rounded curves. It may be said that in its windings its longer 
stretches seem to conform to some extent to a rectangular sys¬ 
tem, its course being for the greater part of this distance ap¬ 
proximately east-west or north-south, and the stretches in the 
intermediate directions being shorter. 
My conclusion is that adjacent to the Wisconsin river the 
minor and perhaps the major drainage developed in post-glacial 
time, on the broad flat ridge of Cambrian sandstone at Kil- 
bourn City and vicinity, is largely controlled by regional sets 
of joints produced by the slight foldings of the Paleozoic forma¬ 
tions of Wisconsin. 
The dells of the Wisconsin also exhibit a magnificent example 
of current bedding. This may be followed from below Kilbourn 
City to the Witch’s Gulch, five miles above. The most common 
phenomena are as follows: The horizontal beds of sandstone 
just above the water are horizontal. When followed to higher 
horizons these are seen to curve upward until they have an in¬ 
clination of 15°, 20°, or even 30°. One may follow mile after 
mile up the stream and find the beds curving from a horizontal 
to an inclined position, the dips usually being down the river. 
After the current beds were deposited it appears that there was 
a time of erosion during which they were cut to an almost per¬ 
fect horizontal plane. Resting upon the truncated edges of 
these beds is horizontal sandstone. In some places the current 
beds run in different directions, two different sets truncating each 
other before the overlying horizontal sandstone which always trun¬ 
cates the upper set of false beds is reached. The appearance of 
the discordant set of beds is very strongly that of unconform¬ 
ity, and the scale is such that if only a part of the phenomena 
were seen, i. e., the tilted and overlying beds, the lower hori - 
zontal beds and their transition into the inclined beds being 
