234 F. W. SARDESON THE REDSTONE QUARTZITE 



tions from an inch to a foot in diameter and infiltrated with calcite. The 

 lower limestones are largel}' "nodnlar," while those 20 and 40 feet higher 

 VL-p are more granular, laminated sedimentary deposit. The Algal lime- 

 stone and the dominance of clay indicate that the area north of the Eed- 

 stone quartzite, between it and the quartzite conglomerate ledge, was occu- 

 pied by quiet water — a lake, in short. The lower limestones are repre- 

 sented, in their "nodular" form, on the west side of the Minnesota river 

 south of Eedstone, at Winkelmann's limekiln, and, again, as far as at the 

 mouth of Kalb creek, there are thin sedimentary limestones and shales 

 with flakes of lime in them, in a zone comprising 5 feet of strata. Traces 

 of lime flakes occur 2 to 3 miles farther west. 



Coarse sands with pebble-bearing strata are known only on the south 

 of Eedstone hill, and very evidently a river flowed by that course from 

 east to west. This pebble-bearing sand occurs some 20 to 40 feet below 

 the top of the formation, along the Big Cottonwood river, at the mouth 

 of Kalb creek. The characteristically bright polished quartz pebbles ap- 

 pear also at New Ulm. This sand is known on the northeast side of the 

 Minnesota Eiver valley for several miles east of Eedstone (in sections 16 

 and 20, Courtland, Nicollet county). The formation there appears to 

 extend eastward, under the glacial drift. Two to 3 miles southeast and 

 south of these last outcrops, Cambrian formations appear, rising to the 

 same height and in place of the Cretaceous strata. The contact of Cre- 

 taceous and Cambrian I have not found, but doubtless the former lies 

 here in an old valley, the south wall of which is of Cambrian rocks. Lime- 

 stone is known on the south side of the Eedstone close to the shelter of 

 that rock, which formed locally the north wall of the Cretaceous valley. 

 Shales should be expected to underlie the pebble-bearing sand, and they 

 have in fact been traced on the right side of the Minnesota for 3 miles 

 below the Big Cottonwood river. The coarse sand deposit is above sands 

 and shales, indicating that stronger current followed as the Cretaceous 

 valley filled. 



In regard to the surface on which the Big Cottonwood formation rests, 

 the evidence indicates a preexisting valley — practically a pre- Cretaceous 

 valley. Since the strata rise to only half the height of the Eedstone 

 quartzite, or some 80 feet above the Minnesota river, the top of that rock 

 may be supposed to have been exposed above the Cretaceous at all stages. 

 The rotting of the dike, as described, and the leaching of the Courtland 

 quartzite are evidently pre-Cretaceous in main. The granite outcrop on 

 the Big Cottonwood river is rotted at least 30 feet and possibly 100 feet, 

 and this would indicate that it had been a hill for ages before the Big 

 Cottonwood formation of the Cretaceous began to surround it. The 

 granite floor, as found in wells at New Ulm, is 300 feet below the top of 



