GEOLOGICAL EXPLORATIONS AND LITEKATUiiE— 1850. 23 



refer, there can l)e no doubt in })lacing- the coarsely crystalline sienite of 

 the Escaiiawl)v and southern part of the primitive district apart from the 

 trap and copper- bearing rocks of Lake Superior.'' 



At the mouth of Dead River SA^enite was observed, and at the first falls, 

 1 mile upstream, a talcose slate. Syenites and various slates were noted 

 at other places in the vicmity of Dead River, and the syenite was seen to be 

 cut very frequently by trap dikes. At "Point No. 2, west of Presque Isle," 

 a junction of red sandstone with syenite is said to occur, but it seems to 

 have had very little significance to the writer, as he does not describe it, but 

 merely asserts its existence. The contact is probably the unconformity at 

 Granite Point. 



Foster, J. W. Notes ou the geology aucl topography of portious of the couutry 

 adjacent to Lakes Superior and Michigan, in the Chippewa land district. Dated ISIay 

 26, 1849. 31st Congress, 1st session, 1849-50. Senate Documents, Vol. Ill, No. 1, 

 pages 773-801. 



J. W. Foster, another of Jackson's assistants, reports the results of 

 his explorations along the Jlichigamme and Menominee rivers to Green 

 Bay. Only one or two observations are of interest to us in the pres- 

 ent discussion. Indications of the presence of iron ore on the north 

 side of Lake IMichigamme are plentiful. Horublendic and argillace(ius 

 slates form a range bounding the lake on the north, and within, the 

 hornblende rocks are beds of c^uartz. In sec. 1, T. 46 N., R. 30 W., where 

 Republic was afterward located, Foster and his associates crossed an 

 almost perpendicular cliff, composed of such pure specular oxide of u-on 

 that its mineral associates were difficult to determine. This pure ore forms 

 the brow of the clift'. Beyond it succeeds a bed of quartzite, containing 

 small specks of ore and large rounded masses of the same material, 

 forming with the quartzite a conglomerate. This is the first mention of a 

 conglomerate associated with the iron rocks, and, strange to relate, this 

 first conglomerate observed was the last one whose significance in the 

 geological history of the region was realizeil. 



The ore was regarded by Foster as continuous with that of Carp 

 River, because the mineralogical and geological associations of the ore in 



