li:fiSUMfi OF LITERATURE. 77 



learn, in addition to the facts already:" presented above, that below No. 1 

 the slates and quartzites of the Animikie lie : 



(2) Soft greenish slat}' schists, which hold lenticular masses of light-colored 

 protogine gneiss, and also beds of diorite. The horizon of the Vermilion iron mines 

 is thought to be near the bottom of this subdivision or at the top of the next, but en 

 the opposite side of a Laurentian axis, dipping north, and that of the Mesabi iron 

 range, in the foregoing subdivision, dipping south. (3) Congiomeritic and quartz- 

 itic slates, which become line, arenaceous quartzites, and also embrace beds of sili- 

 ceous marble. 



Still further north [lie the gneiss and syenite], accepted ... as the Laurentian. 

 [pp. 37-38.] 



WiNCHELL, N. H. The crystalline rocks of the Northwest: Proc. Am. Assoc. 

 Adv. Sci., Thirty-third Meeting, pp. 363-379. Reprinted in Thirteenth Ann. Rept. 

 Geol. and Nat. Hist. Survey Minn., for 1884, 1885, pp. 121-14:0. 



In this paper Winchell divides the rocks of the Northwest into six 

 groups. These groups, in descending order, are as follows, the rocks of 

 the Vermilion range being assigned to Nos. 4, 5, and 6: (1) Grranite and 

 gneiss with gabbro; (2) mica-schist; (3) carbonaceous and arenaceous 

 black slates and black mica-schists; (4) hydromica and magnesian schists, 

 the iron-bearing horizon at Vermilion Lake ; (5) gray quartzite and marble, 

 which in Minnesota seems to run along the south side of Ogishkie Muucie 

 Lake, near the international boundary, including, perhaps, the great slate- 

 conglomerate which is there represented ; (6) granite and syenite with 

 hornblendic schists. This lowest recognized horizon has frequently been 

 styled Laurentian. In Minnesota it is found on the international boundary 

 at Saganaga Lake, and large bowlders from it are included in the overlying 

 conglomerate at Ogishkie Muncie Lake, showing an important break in the 

 stratigraphy. 



Van Hise, C. R. Enlargements of hornblende fragments: Am. Jour. Sci., 3d 

 ser.,Vol. XXX, 1885, pp. 231-2.35. 



Van Hise describes some enlargements of hornblende fragments and 

 crystals seen in the Ogishke Muncie conglomerate as developed on Keke- 

 kabic Lake. A brief description of the macroscopic appearance of the 

 conglomerate, taken from W. M. Chauvenet's notes, is also given. 



Ieving, R. D. Preliminary paper on an investigation of the Archean formations 

 of the Northwestern States: Fifth Ann. Rept. U. S. Geol. Survey, 1885, pp. 175- 

 212, 10 pis. 



In this paper, published in 1885, Irving gives a preliminary account 

 of an investigation of the Archean formations of the Northwestern States. 



