68 THE VERMILION IRON-BEARING DISTRICT. 



Whittlesey, Col. Charles. Geology and minerals. A report of explora- 

 tions in the mineral regions of Minnesota during the years 1848, 1869, and 1864. 

 Cleveland, 1866; 54 pages. 



According to Colonel Whittlesey tlie Minnesota shore of Lake Superior 

 structurally represents the northern edge of a syncline, in the basin of 

 which Lake Superior lies, and we consequently get essentially the same 

 succession of rocks that is found on the southern shore of Lake Superior 

 in Michigan and Wisconsin — a belt of alternating sandstone beds and trap 

 flows, succeeded inland by a belt of trap. These two constitute the series 

 which is known as the Keweenawan. Back of the trap he finds a belt of 

 liornblende rocks, or hornblende-slates, as they are called. This is the 

 Animikie series of the Minnesota geologists. 



Behind the hornblende sj'stem is the imperfectly defined region of the granite, 

 syenite, mica slate, siliceous, and talcose rocks, extending to and across the national 

 boundar}'. The Mesabi range occupies the watershed between the waters of Lake 

 Superior and those of Hudson's Bay. In many cases the syenite and granite appears 

 to be more recent than the metamorphic slates, having all the appearance of 

 intrusive rocks [p. 7]. 



That part of the Vermilion Lake region, including the rocks just 

 mentioned — the mica-slate, siliceous and talcose slates — which lies to the 

 north of the Mesabi range is described in some detail. Leaving the syenitic 

 Mesabi range he proceeds over the portage trail to Vermilion River (now 

 known as Pike River) and passes in the order given over syenite, "gray, 

 compact quartz," mica-slate, and distinctl}^ layered novaculitic quartzite. 

 Just before entering Vermilion Lake fine-grained micaceous rocks are 

 exposed, and these continue along the western shore, becoming more 

 talcose and slaty as the explorer goes north. The slaty laminse strike 

 northeast by east, and dip 75°-80° northwest. These slates are also very 

 much jointed, causing the formation of rhombohedral blocks. On the north 

 shore of Vermilion Lake, Colonel Whittlesey saw and recognized clearly 

 the relations of the granite to the sedimentaries, mica and talcose slate, as 

 he calls the rocks. He says, "The granite appears as a protrusion in the 

 slates, and is therefore more recent" (p. 45). 



