240 F. W. SAEDESON — -THE REDSTONE QUARTZITE 



proper, and on the other side by the level along which the business streets 

 extend. A triangular tract on which the Minneapolis and Saint Louis 

 railway runs south of the Cottonwood river is of the same. This ter- 

 race rests on the top of the Big Cottonwood formation. The 830-foot 

 terrace is occupied by the depots and railway tracks at New Ulm and is 

 traversed by the railways, extending to the Big Cottonwood river and 

 thence three miles beyond it, occupying a great part of the valley opposite 

 Eedstone hill. It rests on the red shale zone of the Cretaceous. These 

 terraces are covered generally by a few feet of red loam over more or less 

 gravel, both of which were made by the river Warren. 



On the left side of the valley the 940-foot terrace runs nearly contin- 

 uously from a mile above to four miles below the Eedstone quartzite bar- 

 rier {6, vohime 2, page 173). The 910-foot terrace extends nearly a mile 

 and the 830-foot terrace forms a broad meadow north of Eedstone vil- 

 lage. All these terraces in the valley passing the Eedstone hill are in 

 strong contrast to the simple valley above New Ulm. 



THE BIO COTTONWOOD VALLEY 



The valley of the Big Cottonwood river Joins the Minnesota on the west 

 side, opposite and a little above Eedstone hill, just at the place whore the 

 river Warren was most diverted by that obstruction. Since the Big Cot- 

 tonwood is tributary here, the cutting of its valley may be presumed to 

 have proceeded pari passu with that of the Minnesota, and to have been 

 influenced in somewhat the same way. The Big Cottonwood valley is a 

 remarkably irregular one, as shown on tlie map (figure 1). It is nearly 

 200 feet deep, cut through the glacial drift and into the Cretaceous sands 

 and shales ; it has broad embayments, with terraces and steep sides. The 

 river meanders from side to side in its valley and repeatedly undermines 

 its bluffs, causing great landslides. Where the river encounters easily 

 eroded sandrock the i;ndermining is rapidly done, biit where shales now 

 appear at river level, the undermining is slow. The entire valley has 

 been made in that same manner. The downward erosion has been accom- 

 panied by wide lateral erosion where soft rock was encountered by the 

 river. The same succession of hard and soft formation is found along 

 the Big Cottonwood as along the Minnesota valley at and below New Ulm^ 

 and since the two rivers cut down pari passu the terraces in the two val- 

 le3's largely correlate. 



While the Minnesota valley was made by a large, flood-like stream — 

 the river Warren — and the modern stage of that river, the Minnesota, now 

 meanders freely within it without conflict with the sides, the Big Cotton- 

 wood valley, on the contrarj'-, has been made by a small river, as it now is. 



