312 THE MARQCJETTE lEOX-BEARING DISTRICT. 



A short distance east ot" the Cascade Brook, in the valley between thfe 

 Negaunee tormation and the Palmer gneiss, is a conglomerate which con- 

 tains i^ebbles of many kinds from the Basement Complex, including green 

 schist and sericite-schist, precisely similar to rocks in the Palmer formation 

 at the Brook section. This conglomerate quickly grades up into jasper, 

 there being, however, at many places several alternations of conglomerate 

 or quartzite and jasper before the typical banded jasper is reached. On the 

 west side of the old open pit of the Volunteer or old Cascade mine is a 

 conglomerate which again contains detritus from the Palmer gneiss, but it 

 is rather probable that this conglomerate belongs to the Ishpeming for- 

 mation, and that the entire Lower Marquette series has been removed 

 by erosion. Adjacent to the center of sec. 30 and to the westward are 

 large exposures of the Ajibik quartzite, and at one place this becomes 

 conglomeratic. 



Sees. 27 and 38, T. 47 N., R. 27 w. — A sliort distauce northwest of the center of sec. 

 28, T. 47 N., R. 27 W. (Atlas Sheet XXVI), on the north side of the expos- 

 ures, is a knob of quartzite-conglomerate, and south of this, a little farther up 

 the hill, is a white mashed gneiss, which at so many places is the uppermost 

 member of the Palmer formation. In the NW. ^ sec. 27 and in the NE. ^ 

 sec. 28 are ferruginous mica-slates interstratified with amygdaloids. As 

 platted on the ground, there are three belts of amygdaloid. These slates 

 when first examined were thought to have a regular east-west strike and a 

 uniform northern dip. When the ledges were closely examined the slates 

 were seen to be intricately folded into a series of northern-dipping isoclinal 

 folds, the axes of which plunge steeply to the east. A specimen from one 

 of the more open of these folds shows a difference of dip of only 32° 

 between the two legs (PI. XXXV, fig. 1). While there is everywhere a 

 northern dip and an east-west strike, the same belt of slate is repeated 

 many times, and the (juestion arises whether the three apparent belts of 

 amygdaloid are not really one, being repeated by isoclinal folding. 



When studied in thin section, these slates are found to be exactly like 

 the heavily liematitic and magnetitic slates which occur at the transition 

 horizon of the Siamo slate and the Negaunee formation. These are 

 described on a subsequent page. 



