354 HALL AND SAJRDESON PALEOZOIC FORMATIONS OF .MINNESOTA. 



One of the authors while collecting lower Paleozoic fossils in southern 

 Wisconsin had occasion to note quite closely the relations of these for- 

 mations now under consideration. His observations convinced him that 

 the Lower Magnesian was folded locally into a succession of ridges and 

 depressions. Every character showed this folding to be due to lateral 

 pressure. The structural appearance, the uneven character of the folds, 

 and the parallelism of the lamination of the rock and the configuration 

 of the Saint Peter strata on the dolomite beneath, all pointed to that cause. 

 The lamime of the two formations were perfectly conformable. The con- 

 clusion is that the folding of tic M«j/nesiui) cxt> adrd upicurd and involved 

 the Saint J'i U r. 



The conditions above cited were se -:i in the Pecatonica valley, hi 'tween 

 Blanchardville and the Wisconsin-Illinois boundary, at several different 

 localities: and a similar folding of the Magnesian has already been men- 

 tioned as occurring at Northfield, Minnesota. 



2. Considering now the Saint Peter alone, we note that at south Saint 

 Paul it shows many minor faults. In regradinp; a street from the Chi- 



WSMISSmmmz 



wmmrn^ 



. 



Figure ?,. — Minor Faults and Color Markings of the Saint Peter Sandstone at. south Saint Paul. 



1 = Normal Saint Peter sandstone, colored along lines of bedding ; 2 = Saint Peter sandstone, 

 colored aud cemented by infiltrations from above, and covered by a layer of river gravel mingle. 1 

 with bowlders. 



cago. Saint Paul and Kansas City railway shops to the south Saint Paul 

 packing-houses considerable cutting has been done in the side of the 

 sandstone bluff along which the street extends. - These fresh exposures, 

 a quarter of a mile or more in length, afford an excellent opportunity to 

 study the structural features of the middle portion of this formation. 

 These faults are of interest, too, in that they Occur in almost incoherent 

 sands, just as clearly defined as in the tinner and more sharply lami- 

 nated beds. The faults are sometimes vertical, yet oftener inclined in 

 various direction-, prevailingly north and south. Figure 3 sketches 

 these fault-. 



•">. In the third place, at a number of localities, particularly within the 

 Saint Anthony area, opportunities are afforded for studying the contact 



