PLATES (PAGES) XXV AND XXVl. 



BROWN AND REDWOOD COUNTIES, 1884. WARREN UPHAM. 



Along the southern and southwestern limits of these counties the general surface 

 exhibits a noticeable increase of elevation, suggesting that the Potsdam quartzyte, 

 which rises abruptly in northern Cottonwood and northwestern Watouwan counties, 

 strikes continuously toward the west and northwest, giving origin to this increase 

 of hight. This elevation was formerly known as the eastward continuation of the 

 Coteau des Prairies, the crest of which is further west. The streams from this ridge, 

 or plateau, descend to the Cottonwood river, which flows southeastwardly along its 

 base as if it had been determined by a valley formed in glacial time by the barrier 

 of the ice on the northeast. Such stream and valley appears to have united with 

 the Little Cottonwood valley by the gravelly valley occupied by Mound creek in 

 Stately. It probably thence continued through Bashaw and Molligan into Albin, 

 finally being diverted southwardly through the valley of lake Hanska, which appears 

 to lie nearly parallel to the direction of a third moraine which Mr. Upham has indi- 

 cated in his report on these counties. The water from this drainage probably entered 

 the lake then existing over the region of Blue Earth county and found its outlet into 

 the Des Moines. Through eastern Brown county this glacial drainage course is 

 apparently obscured by till and perhaps by lacustrine deposits. 



These counties afford broad expanses of fertile prairie, with only scant timber 

 along the streams or on the borders of the lakes. Although the drift surface appears 

 thus flat, when viewed at large, yet it is found, on closer examination, to possess 

 minor undulations or broad swells varying in extent, hight and direction, generally 

 without any uniform trend, and sometimes oval or nearly round. These give such 

 diversity as to afford local drainage to most of the country, but also cause the occur- 

 rence of swamps and lakes. The highest land in Brown county is in sections 31, 32 

 and 33, Stately, where the hight is 1,200 to 1,250 feet above the sea, and 200 feet 

 above the Cottonwood river in the northern part of Stately, but 100 feet below the 

 top of the plateau a mile further south. The Minnesota river leaves this county at 

 about 778 feet above the sea. In Redwood county the highest land is in the south- 

 west part of Springdale, 1,400 feet above the sea, 300 feet above the Cottonwood ten 

 miles to the north, and (500 feet above the lowest land of this county, at the shore 

 of the Minnesota river at the northeast corner. 



The Archean rocks, with more or less of an overlying of Cretaceous, under the 

 drift, extend under both these counties. The Cretaceous, and especially the drift, 

 serve to conceal the original roughness of the Archean surface, which, however, 



