222 THE MAKQUETTE IKON-BEAIIING DISTEICT. 



side ot" the Lower Marquette series the Mesnard formation extends continu- 

 oush', south of the Archean, from Lake Superior to the west side of sec. 

 29, T. 47 N., R. 25 W. For several miles to the west of sec. 29 there are 

 no exposures, l)ut just east of Carp River a heavy belt of quartzite again 

 appears next to the Archean and runs westward as far as Teal Lake. The 

 peculiar distribution of the formation is explained by its folding, which is 

 considered below. 



On account of the resistant character of the quartzite, it constitutes, 

 south of Marquette (Atlas Sheets XXXVIII and XXXIX), three prominent 

 ranges, tlie first including Mount Mesnard, the second being south of the 

 Archean island in sees. 2 and 3, T. 47 N., R. 25 W., and the last being 

 adjacent to the Archean to the south. As the formation grades from a piu-e 

 vitreous quartzite to a slate, its resisting power is verj^ diverse, and its 

 complicated folding gives an irregular distribution to the different belts, 

 so that, while the ranges have the distribution mentioned, the topography 

 in detail is exceedingly rough. In crossing- the formation one climbs a steep 

 ledge, plunges into a sharp ravine, then ascends another bluff, to again 

 climb down; so in crossing a range one traverses a series of exceedingly 

 steep ridges. 



FOLDIN&. 



At the east end of the district the quartzite is folded into two closely 

 compressed east -west synclines, with a central anticline, the quartzite 

 occupying the entire breadth of the Algonkian in the section just east of 

 the State prison. (Atlas Sheets XXXVIII and XXXIX.) East of this line 

 the overlying dolomite appears in the southern syncline. In the section 

 running south from Mount Mesnard both the northern and southern sjni- 

 clines show the overlying dolomite, but on the anticline between erosion 

 has cut to the Archean North, at Mount Jlesnard, another syncline appears. 

 West of ilesnard the northern belt of quartzite has a monoclinal dip, ver- 

 tical or south at a very high angle. When examined in detail, however, it 

 is found in its slaty phases to be rolled into a set of minor overfolds, which, 

 in passing from the Archean toward the center of the Algonkian, show 

 steadily higher and higher members. In the southern belt the quartzite 

 north of Lake Mary constitutes a shallow synclinal trough. (Atlas Sheet 

 XXXVII.) 



