262 THE GEOLOGY OF MINNESOTA. 



[Loess loam. 



original condition, which is spread over the uplands, so far as seen in Winona county. In cases 

 where it is exposed along the roads by grading it does not now show that condition. But the expo- 

 sures are nearly always 1 along old slopes, where the present condition is due to former sliding 

 down from above, this having destroyed the strata if they once existed. 



At Pickwick was taken the section illustrated by figure No. 9, on page 246, which is as fol- 

 lows, in ascending order: 



1. St. Croix sandstone. 



2. Stratified fine lo im, yellowish, with an uneven, eroded, upper surface, - - - - IS feet. 



3. Waterworn, rotted debris from the bluff with lenticular patches of stratified sand, similar to those 



seen in the Potsdam conglomerates at lake Superior, '------ 18 feet. 



4. Thin strata of clay, more or less mingled with liner materials like those of No. 3, - - 4 feet. 



5. Same as No 3. ______...__. 3 feet. 



6. Stratified fine loam, ........... 6 feet. 



No. 6 rises, where this section is made, in the slope of the valley somewhat above the 

 level of the valley fiat, but seems to consist of the same deposit as the surface of the valley flat 

 Across the creek, but a short distance from the foregoing, is a section exposed in the materials 

 of the valley* flat, covering about eighteen feet of the same interval, and occupying about 

 the level of No. 3. This consists wholly of fine stratified loam ; showing either that the 

 present valley was excavated after the deposit of the materials of the foregoing section and subse- 

 quently covered over with a stratified fine loam, or that the fine loam was continuously deposited, 

 but was interrupted along the then talus slopes by the accumulation of gerolkf from the bluffs, 

 The basin-shaped contour of a section across the valleys, taken in connection with the existence 

 of these beds of coarse material within the loam near the base of the bluffs, seems to indicate the 

 latter as the true hypothesis. 



FIG. 13. FROM THE BLUFFS AT PICKWICK. 



The loess-loam. The last consideration mentioned above has a bearing 

 on the question of the origin of the loess-loam. If it be true that this 



The flat here designated valley flat, is the lowest flat of t he valley. It is that which contains the most tillable land. 

 It has no reference to the high terrace; but sometimes instead of being flat it slopes gradually upward on both sides of 

 the valley to the bluffs, or to the foot of the high terrace. 



Where is no English word thai expresses the significance of this from the German. This deposit is a loose, semi- 

 rounded, quickly accumulated debris that is precipitated by freshets down the gorges into the valleys. 



