NEW ULM BASAL CONGLOMERATE 229 



drift 4 to 6 miles from Eedstone. The formation at Bedstone appears to 

 continue in force, under the glacial drift, in that direction. To the Avest 

 it seems to end abriiptl_y, since the granite rises in place of it in the Big 

 CottonAvood valle)^, as already described. The total thickness of the for- 

 mation is not knoA^m. The estimated 300 feet of strata in the exposed 

 portion may be too little or possibly too great an estimate. Concealed 

 faulting may decrease the apparent thickness or possibly increase it. 

 LikeAvise the extent of this formation betAA^een the lowest exposed stratum 

 and the • granitic rocks beneath it is uncertain, because the amount of 

 doAvnthroAv Avhich the quartzitc has siiffered in relation to the granitics, 

 seen Avestward of it, is unknoAvn. The resistance of the quartzitc to 

 degradation from surface exposure is strikingly greater than that of 

 granite, and therefore the relatiA^ely loAver outcrops of the granitic rocks 

 is not good evidence that they Avere not once as high or higher than the 

 quartzitc at Eedstone. Since the extent of the original dislocation is un- 

 knoAvn, the depth to granite under the quartzite is uncertain and, more- 

 over, the existence of other geologic formations betAveen them is possibly 

 to be expected. Although it has been assi^med by geologists that the 

 quartzite at Redstone rested on the granitic rocks because these appear 

 close beloAV the jSTcav Ulm conglomerate quartzite, v^^hich Avas supposed to 

 be the basal beds of the Coiirtland quartzite, yet there is reason for think- 

 ing to the contrary. That conglomerate is of Middle Cambrian rather 

 than of the "pre-Cambrian." 



The ISTeav ITlm basal Conglomerate: Cambrian 



The quartzite conglomerate Avhich outcrops on the left side of the 

 Minnesota river, opposite Ncav Ulm, a mile and a half above Eedstone, 

 has been heretofore considered by geologists as the basal part of the Court- 

 land quartzite. It lies closely over the granitic rock; its strata dip 10 to 

 15 degrees, as if dislocated; it is a quartzite, and the contained pebbles, 

 as reported, Avere all from formations older than the Courtland quartzite, 

 Avhence the conclusion Avas easily draAvn that it represents the basal part 

 of the quartzite as seen at Eedstone. In speaking of the contained peb- 

 bles in this conglomerate, Ilpham says {6, volume 2, page 159) : "Neither 

 the granite that outcrops close at the Avest nor the quartzite that occurs 

 on a large area II/2 to 3 miles distant toAvard the southeast seems to be 

 represented." C. W. Hall {10, page 23) makes essentially the same 

 statement, and N. H. Winchell (9, page 156) says: "Probably there is no 

 one Avho Avould call in question that this conglomerate and quartzite (that 

 is, Courtland quartzite) are earlier than the KcAveenawan eruptive age." 



In company Avith Benedict Juni, I examined the ledges of the NeAV Ulm 



