236 THE MARQUETTE IRON-BE AEIXG DISTRICT. 



into quartz-schists. Doubtless the chert, jasper, and quartzite-Uke frag-- 

 ments are deriv^ed from the veins of these kinds which are found in the 

 green schists of the Northern Complex, although it is possible that a ])art of 

 them are derived bv dynamic action from vein chert and quartz deposited 

 in the formation itself before the final folding. The feldspathic quartzite 

 contains very abundant simple, large grains of feldspar, whicli are in some 

 cases distinctly enlarged. The graywackes, slates, and quartzites do not 

 diflfer from the ordinary phases of the formation. 



Mount Mesnard. — Mouut Mesnard (Atlas Sheet XXXVIII) is a large 1:)lufif 

 in the west lialf of sec. 3.5 and the eastern part of sec. 34, T. 48 N., R. 2.5 W. 

 In structure this mountain is a closely compressed syncline, the formations 

 concerned being the Mesnard quartzite and the Kona doloinite. This fold 

 is so closely compressed as to make the dips everywhere approximately 

 parallel, varying from 80° to the south to vertical. The major part of the 

 mountain and the two northern of its higher 2:>oints are made up of the pure, 

 vitreous, broken and cherty Mesnard quartzite. Between this and the Kona 

 dolomite is a layer of slate, with a transition schistose quartzite. The slate, 

 being less resistant than the quartzite or the cherty dolomite, is marked by 

 an irregular longitudinal depression. In the readily yielding slate are seen 

 strong- evidences of masliing, the major readjustment in folding apparently 

 being here. Constituting the center of the syncline is a second row of 

 points, one being the culminating peak. These are composed of the vertical 

 layers of the closely compressed Kona dolomite. The steep south brow is 

 composed of the slate, and on the south flank of the bluff is again the 

 Mesnard quartzite, making the other limb of the syncline. This syncline 

 has minor corrugations and a westward pitch, as a consequence of which 

 the fingers of the Kona dolomite unite toward the west into a broad area of 

 this formation. The south and southeast slopes of the bluif are composed 

 of the Jlesnard quartzite. Because of the westward pitch of the formations 

 and the topograph}^ the belt of Kona dolomite terminates a short distance 

 east of the cidminating peak, as a consequence of which the eastern half of 

 the ridge is composed wholly of the Mesnard quartzite folded back upon 

 itself. 



East of the State prison the south arm of the Mesnard quartzite con- 

 stitutes a ridge, a point of Lake Superior, and a small island off" the coast. 



