174 THE CRYSTAL FALLS IROD-BEAllING DISTRICT. 



Specinieiis of these iiiica-scliists and clilorite-scliists were regarded by 

 Wifhniann a.s nonfragmeiital/ Tliis is little to be wondered at, since lie 

 had never studied their field relations. In the field these rocks can, liowever, 

 be traced into rocks of unquestionablj^ fragmental origin. The same speci- 

 mens were described as "micaceous quartz-schists" by Wright.^ Wright 

 also mentions a staurolitiferous mica-schist in the Michigamme River, and 

 also in the Paint River. The second occurrence is 2^ juiles northwest from 

 the first and in the direction of its strike. Julien describes metamorphic 

 rocks from Long Portage as "fine-grained grayish black gneisses."' From 

 these descriptions it is seen that the least altered sedimeutaries on the one 

 hand and the cr^^stalline schists on the other were recognized by these 

 earliest students of the metamorphic rocks. However, the fact to which 

 I would especially call attention, that the crystalline schists are derived 

 from the clastic rocks by metaniorphism, was evidently not understood. 



The contact action produced by igneous intrusions into these series 

 of sedimeutaries will be discussed in connection with the intrusive rocks 

 (p. 194 et seq.). 



IGNEOUS ROCKS. 



The igneous rocks Avhich are found to have penetrated the Uppej- 

 Huronian after the important folding of the rocks took place are not 

 included here, but may be found described under the heading "Intrusives" 

 (p. 187). In this place it is desired to call attention to certain hornblende- 

 gneisses which occur near Norway carry, on the Michigamme River, and 

 also extend in large outcrops west of the river for about 2 miles and east 

 for about a mile. These are interlaminated in thick masses with the mica- 

 schiists. They are perfectly crystalline hornblende-gneisses. They consist 

 of common hornblende, quartz, feldspar, and some iron oxide. The horn- 

 blende is present in large quantity, the parallel plates of that mineral 

 giving the rock its schistosity. None of the minerals are automorphic, but 

 all occur in interlocking grains. Without going into a detail description 

 of these rocks, it will suffice perhaps to state that they are similar in all 

 respects to hornblende-gneisses which in other parts of the Lake Superior 



' Op. cit., pp. 635, 646. 

 - Op. cit., p. 693. 

 ■■Op. cit., p. 130. 



^Bull. U. S. Geol. Survey No. 62, by G. H. Williams, 1890; Mou. U. S. Geol. Survey, Vol. XXVIIl, 

 lip. 152-1.59, 203, 208. 



