184 THE CAMBRIAN. [bull. 81. 



of the survey. In this he affirms that the horizontal fossiliferous beds 

 referred to the Potsdam by Dr. Owen, Prof. Hall, and other authors is 

 above the true Potsdam of New York, and that the latter is represented 

 by the rocks of the copper-bearing series in the west ; also, that no fos- 

 sils representing the Primordial fauna have yet been discovered in the 

 west nor have any been found in the western representative of the Pots- 

 dam ; and finally, that the second fauna of Barrande is found in the 

 Quebec group of Canada and in the St. Croix sandstone of the west, 

 lying in each case above the Potsdam sandstone. 1 



An article by Dr. J. H. Kioos, translated by Prof. Winchell, describes 

 the rocks of the Falls of St. Anthony and the St. Croix River, and gives 

 a description and a diagrammatic section of the river bank at Taylor's 

 Falls, illustrating an unconformity between the Potsdam sandstone and 

 the subjacent copper- bearing rocks. 2 



In an account of the geology of a deep well drilled at Minneapolis 

 Prof. Winchell states that the drill passed through sandstone in the 

 lower portion of the well as indicated in the following section : 3 



Feet. 



1. Drift , 10 



2. Trenton liinestoue 24 



3. Light, crumbling sandstone (St. Peter?) 125 



4. Brown-red pipestone clay 2 



5. Potsdam sand 42 



6. Red quartzite, Potsdam 102 



7. Light- colored Potsdam sand and shales 722 



8. Red Potsdam sandstone and shales at least 347 



1,374 



Particular attention is called to the brown-red pipestone clay of the 

 section, which is the equivalent of No. 12 of that section on page 212. 

 No. 6 of the section quoted is compared to a layer of red quartzite, seen 

 at New Ulm, Minnesota, and at Baraboo, Wisconsin. Commenting 

 upon this he says : 



Thus we find an interhedded red qnartzite in the Potsdam formation similar to 

 those seen in the same formation in the Black Hills and in several other places in 

 the Rocky Mountain region. 4 



Attention is called to this statement as it is a correlation of a quartz- 

 ite of the Upper Cambrian rocks of the Black Hills with a bed of 

 quartzite in the Sioux quartzite series of Minnesota and the Baraboo 

 quartzite series of Wisconsin. 



In a tabulation of the strata beneath the lower fossiliferous sand- 



1 The Potsdam Sandstone. Geol. and Nat. Hist. Survey Minnesota, 10th Ann. Rep. for 1881, 1882, 

 p. 136. 



2 Geological notes on Minnesota. (Translated by N. H. Winchell.) Geol. and Nat. Hist. Survey 

 Minnesota, 10th Ann. Rep. for 1881, 1882, pp. 186-200. 



3 The geology of the deep well drilled by C. C. Whelpley at Minneapolis, at the "C" Washburn Mill. 

 Geol. and Nat. Hist. Survey Minnesota, 10th Ann. Rep. for 1881, 1882, p. 217. 



4 Op. cit., p. 214. 



