THE LOWER HURONIAN. 277 



VEKMILIOK LAKE AREA OF THE EOWER HURONIAN SEDIMENTS. 



DISTRIBUTION, EXPOSURES, AND TOPOGRAPHY. 



Distribution. — The Lower Huronian of this area has been found to 

 extend very much fai'ther west than it is shown to do on the accompanying 

 map (PL II). It has been carefully studied, however, only in the area out- 

 lined thereon, and in this description we must consider it as beginning at the 

 western limit of the map, where the rocks of the series cover a very broad 

 area, corresponding in width practically with the width of the map. Its 

 greatest breadth is something like 11 miles in Ts. 61, 62, and 63 N., R. 16 

 W. As this area, as outlined upon the map, is followed to the east, we note 

 that it is subdivided into a number of smaller areas by the various fingers of 

 Archean rocks that project westward into it. Beginning at the south, the 

 area underlain by Lower Huronian rocks is found to extend eastward very 

 nearly to Bear Head Lake, and on the north from the Archean near West Two 

 Rivers southward to the limit of the area mapped. Indeed, a reconnaissance 

 shows conclusively that the same sediments continue beyond the limits of the 

 map, and are practically bordered on the south by the Griants Range granite. 

 The next area north of this projects eastward only so far as the town of 

 Tower. It is but a short tongue, and is bounded on the south by the 

 Archean greenstone and on the north by this greenstone and the associated 

 iron-bearing formation which constitutes Lee and Tower hills. North of 

 this there is a third tongue, occupying the valley between the anticlines of 

 Tower and Soudan hills, projecting eastward at least as far as the village 

 of Soudan. North of Soudan Hill, and occupying in general the basin 

 in which Vermilion Lake lies, there occurs the main portion of the area 

 imderlain by the Lower Huronian sediments. This is alsp that part of the 

 area in which the best exposures occur. The rocks of this area have l^een 

 followed eastward as far as sees. 2 and 15, T. 62 N., R. 14 W. The main 

 area of the Lower Huronian sediments around Vermilion Lake may be 

 subdivided into a number of smaller areas, due to the structural relations 

 of the rocks. On the east shore of Vermilion Lake, for example, there are 

 a number of smaller tongues into which the area can be divided. These 

 will not here be described in detail, but may be found outlined on the 

 maps in the accompanying atlas. The length of this Lower Huronian 

 belt from the western limit of the area mapped to the eastern end of the belt 

 in which the exposures occur is about 17 miles. The Lower Huronian 



