BIG COTTONWOOD VALLEY 241 



at all stages of its making. An old high channel, representing an early- 

 stage of the river, is found crossing section 32, 'New Ulm. This chan- 

 nel is sharply defined and in size indicates a river like the present one. 

 It is cut through the upper glacial drift only. Another such channel, in 

 section 4, Milf ord, runs across to the mouth of Kalb creek, and thence a 

 little south of and parallel to the present river's course. The part of this 

 channel below Kalb creek cuts across even the 830-foot terrace, and there- 

 fore was followed by the creek as late as the modern stage of the Minne- 

 sota river ; but that part above the creek was abandoned earlier. 



The Big Cottonwood crosses the 830-foot terrace of the Minnesota val- 

 ley, and it has there a narrow course, excepting above Kalb creek, where 

 it meanders back against the bluff. At that place it made a wider way 

 and evidently removed the larger part of what I call an 870-foot terrace, 

 having intercepted Kalb creek. The narrow course or valley reveals the 

 relation of the Big Cottonwood river to the Minnesota river in its modern 

 stage. The earlier relation at the junction of the two valleys is not well 

 shown by terraces, these having been cut away by the meanders of the Big 

 Cottonwood. I am inclined to think, however, that there is a gravel- 

 filled former channel of the Big Cottonwood river which runs through the 

 830-foot terrace from the mill in northeast direction to the Minnesota 

 river and which was abandoned at a time when the 830-foot terrace still 

 served as floodplain for the river Warren. The river has been a swift 

 stream and heavily loaded with sediment at all stages, as it still is, and it 

 could have cut and refilled a channel quickly. 



Apparently the general effect of the tributary stream should be to crowd 

 the river Warren and the Minnesota toward the opposite bluff — that is, 

 against Bedstone hill — by means of the loads of sand and gravel which 

 must have been thrown into the side of the main valley. 



Conclusion" 



From the foregoing descriptions it may be seen in particular that the 

 Bedstone quartzite, or that which now composes Bedstone hill in the Min- 

 nesota valley, has stood with remarkably little change through many 

 geologic ages. For the greater part of the time since the pre-Cambrian 

 period its top has been exposed to destructive forces of the atmosphere. 

 Its history may illustrate the many times greater power of resistance 

 which a surface exposure of a quartzite mass may have over that of ordi- 

 nary rock formations. Even the granite rocks and porphyry dike appear 

 weak in comparison. 



In pre-Cambrian time the quartzite was intruded and displaced, prob- 

 ably so as to lie lower than adjacent granitics, and then by the relatively 



