80 THE VERMILION IRON -BEARING DISTRICT. 



feet. (5) Conglomerate, consisting of sandstone pebbles and traces of black 

 slate inclosed in siliceous cliloritic schist. (6) Compact homogeneous rock, 

 composed of quartz grains, chlorite, hornblende, plagioclase feldspar, and 

 calcite. This I'ock may be an eruptive quartz-diorite, but is considered a 

 metamorphosed sedimentary transition bed between 5 and 7. (7) Black 

 clay slate, fissile and sonorous. It occupies a broad area north of Ver- 

 milion range. In section 28 huge masses of jasper form the crown of 

 the arch and are embedded in green schist, with Avhich they agree in 

 strike and dip. The jasper blocks are rectangular and several hundred 

 feet long; the ends of the bands come out squarely to the contact with the 

 schist as to a fault 



Ikving, R. D. Is there a Huronian group?: Am. Jour. Sci., 3cl. ser., Vol. 

 XXXIV, 1887, pp. 204-216, 2-±y-263, 365-374. 



In these papers Irving discusses the separability^ of a Huronian group 

 from an underlying series and demonsti-ates the possibility of such separation 

 in the original Huronian region, in the Marquette and Menominee districts 

 of Michigan, in the Penokee district of Wisconsin and Michigan, and finally 

 in the Vermilion Lake region of Minnesota and Canada (Ontario). In the 

 Vermilion region the gently tilted Animikie series of slates, gray wackes, and 

 iron-bearing rocks, with interstratified sheets of diabase and gabbro, resem- 

 bles very strongly in lithologic aspect the Penokee series of the south 

 shore arid rests in palpable unconformity upon a folded series of schists, 

 granites, and gneisses. Above it is the Keweenaw series, which bears the 

 same unconformable relations to the underlying rocks as it does to the 

 Penokee series. 



Thus the Animike series occupies very plainlj^ the stratigraphical iDosition of the 

 original Huronian and of the various iron-bearing groups of the south shore of Lake 

 Superior. Since it is also intrinsically ,so extraordinarilj^ like the Penokee series as 

 to leave no doubt of their ideutitj'', and .since the Penokee is as evidently the equiva- 

 lent of the original Huronian, we seem to be left no choice as to calling the Animike 

 Huronian also [p. 263]. 



North of the Animikie beds are schistose iron-bearing rocks, which 

 extend from Vermilion Lake to the vicinity of Knife and Saganaga lakes. 

 These are flanked by gneisses and granites, and on account of their litho- 



