278 THE VERMILION IRON-BEAKING DISTRICT. 



sediments within this area are subdivisible into conglomerates and slates, the 

 formations occurring intermediate between these having been classed with 

 one or the other, according to the predominance of the one or other kind of 

 rock in the outcrops. The conglomerate of this area has been called the 

 Stuntz conglomerate." However, the two subdivisions of the series in the 

 Vermilion Lake area are correlative with the Ogishke conglomerate and 

 Knife Lake slates of the typical areas in the eastern part of the Vermilion 

 district, and will be called hj the same name in the description of the 

 western area. 



JExposures. — On the islands and on the shores of Vermilion Lake the 

 exposures of the conglomerate are, on the whole, excellent, and are both 

 frequent and of large size. In the inland areas, however, the exposures 

 are not so numerous and are usually small. 



The slates are not so well exposed on the islands and shore of 

 Vermilion Lake as are the conglomerates, but exposures do occur, and 

 tliey are usuallj^ of considerable areal extent, well cleared off, and good. 

 There are likewise good exposures in the broad area underlain by the 

 slates to the south and southwest of Tower, which is fairly well dissected 

 by stream erosion. This statement is especially true of areas in the 

 immediate vicinity of Pike River and along part of the course* of West 

 Two Rivers. 



Topography. — Considered broadly, the Lower Huronian rocks of this 

 area occupy relatively low ground, the higher eleA'ations being formed by 

 the Archean greenstones and the iron-bearing formation, this arrangement 

 separating the Lower Huronian sediments into the various troughs which . 

 have already been desci'ibed. The topography of the areas occupied by 

 the Lower Huronian sediments has already been referred to (p. 36). It is 

 fairly rugged, but there are no great elevations. The rocks have been 

 carved into a series of north-northeast to south-southwest trending, rounded 

 ridges separated by valleys occupied by swamps, streams, or "lakes. 



STRUCTURE. 



Considering the western part of the Vermilion district broadly, it will 

 be seen that the Lower Huronian sediments occupy a great synclinorium, 

 trending N. 80° E., with Vermilion Lake lying in its broadest part, and 

 that the sediments swing around the anticline of greenstone south of 



aGeol. and Nat. Hist. Survey of Minnesota, Final Kept., Vol. IV, 1899, pp. 282, 525-538. 



I 



