168 Proceedings. 



Lepoiiiis gibbosus. 



Coregonus artedi. 



Perca americana. 



Percina caprodes. 



Lota maculosa. 



Uranidea (small, and mouth injured). 



The secretary was directed to extend the thanks of the Acad- 

 emy to Mr. Washburn for this valuable series of specimens. 



Mr. M. F. Hulet presented a key to the Academy which was 

 accompanied by the following description : 



"This key was at one time used at Jamestown, Va., and afterwards with 

 its lock taken to Crab Orchard, Ky., and there used on the first jail ever built 

 in the state of Kentucky. It has been in use over one hundred and twenty- 

 five years and how much longer is not known." 



The secretary was instructed to convey the thanks of the 

 Academy to Mr. Hulet. 



N. H. Winchell then presented the topic, "the iron bearing 

 formations of Northeastern Minnesota." 



[abstkact.] 



Professor Winchell gave by means of a sketch-map of the geology of 

 the northeastern part of the state, the distribution of the formations that 

 carry the principal ore deposits. 



In ascending order he mentioned first the green schists in the vicinity 

 of Tower, which he described as embracing the ores mined near Vermillion 

 lake and as extending northeastward in two forks, one running on to Hun- 

 ter's island and the other as extending further south to the neighborhood of 

 Gunflint lake and passing unconformably below the Animike slates and 

 quartzites. These green rocks are mainly basic and probably of volcanic 

 origin, but much changed. Above this formation he found the Animike 

 rocks stretching from Pigeon point to the Mississippi and St. Louis rivers. 

 These strata, with their associated gabbros and quartzites make the Mesabi 

 range. They overlap the foregoing and also the gneiss of the Archean. In 

 the vicinity of Gunflint lake, and at points considerably further southwest 

 they are known to carry large amounts of iron ore. While the most of the 

 ore in the underlying rocks is hematite, the most of that in the Animike is 

 magnetite, while hematite and limonite prevail further west. In the former 

 the sheets stand nearly vertical. In the latter they are generally nearly hf ri- 

 zontal. Overlying the Animike is the great gabbro overflow in which are found 

 large deposits of titaniferous magnetites. This rock, being considered the 

 base of the Keweenawan, grades oif by various alternations of eruptive with 

 sedimentary rocks, with indefinite variations of lithology, into the Kewee- 

 nawan. 



He described a great quartzite, which he had named Pewabic quartz- 

 ite, as the rock first below the gabbro, and its upper portion interbedded 

 with the gabbro, fixing the date of the eruption of the gabbro. This quartz- 

 ite furnishes olivenitic magnetite, non-titanic, and is at the bottom of the 



