SOUDAN FORMATION. 193 



Vermilion range of Minnesota. At this place the jasper stands with a dip 

 of about 85° west, with the greenstone both to the east and to the west of 

 it. One might be inclined to say, and with good reason from this part of the 

 exposure, that the jasper is included in or interbanded with the greenstone. 

 However, as we go over the end of the exposure, coming south down the 

 hill along the strike, it can be seen that this relation is due to the exceed- 

 ingly close infolding. The jasper is closely compressed and lies in a 

 syncline of greenstone, and in the inclined section through the jasper and 

 greenstone displayed on the hill slope, the greenstone can be seen to pass 

 down under the jasper, from both the east and the west sides. Indeed, 

 at one place a subordinate anticline of greenstone was observed projecting 

 up through the jasper, the jasper wrapping around it and dipping away 

 from it. On Otter Track Lake essentially the same relations can be seen to 

 exist. Actual contact between the iron-bearing formation and the green- 

 stone was observed, but no fragmental material occurred between them. 

 Clearly, however, the jasper overlies the greenstone, having been deposited 

 upon this as a basement, for the bands run parallel with the contours of the 

 greenstone mass. In this particular instance the exposures are not quite so 

 good as those upon Jasper Lake, but are still good enough to enable one to 

 determine the relations with certainty. On Emerald and Big Rock lakes, 

 both of which lie in Canadian territory, north of Knife Lake, there are 

 several exposures of jasper in intimate association with the greenstone. 

 All the jaspers of Emerald Lake, especially, are beautifully and curiously 

 folded. This folding is particularly well seen on the western edge of the 

 large island about a mile and a half west of the end of the lake. As one 

 rows along the shore he may see most intricately folded jasper bands which 

 closely resemble the jaspers on Otter Track Lake figured by H. V. Winchell 

 in the Minnesota reports. There are fan-shaped folds and curious inter- 

 lockings which would be almost incredible if not seen. The jasper, 

 although so rigid, has evidently obeyed the law of flowage by filling up 

 every chink and comer throughout the mass. It is still somewhat question- 

 able how far this formation may have been folded before it was jasperized. 

 At this ledge upon the island the broad jasper bands were seen to be bent 

 around in a curve having a radius of from 2 to 4 inches, sections across 

 them giving a roundish surface, making them appear almost like a series of 

 closely laid pipes. 



MON XLV — 03 13 



