THE PRECAMBRIAN ROCKS OF THE CANTON QUADRANGLE 49 



Quartz schists, as has been observed, are related to the normal 

 Grenville crystalline limestone through the curious quartz-mesh 

 transition phase already described. The visible gradation, how- 

 ever, is more satisfactory toward the schist than toward the lime- 

 stone end of the series, and this feature was referred to in the de- 

 scription of the quartz-mesh limestones of Van Rensselaer Creek 

 valley. The quartz schist is not abundantly developed at this local- 

 ity, but is found here and there among the group of quartz-mesh 

 limestone hills which occupy the middle of the limestone valley. 

 The laminae vary from one-fourth of an inch to 2 inches in thick- 

 ness and are sometimes slightly crinkled, but never crenulated with 

 the intensity observed at other points, such as that shown in plate 

 3, lower figure. 



The largest area of quartz schist noted is located about a mile 

 west-northwest of North Russell, where it forms a number of very 

 rough, jagged outcrops on the hills traversed by the north-south 

 road. The rock is of substantially the same character as that at 

 Van Rensselaer creek, but the associated quartz-mesh variety is 

 practically absent. The appearance of the outcropping surface and 

 the intense compression of the formation are shown in plate 3, 

 lower figure. The pencil, showing the scale, is oriented in the 

 direction of the pitch. This plunges about 30° in the direction N 

 75 °W, which is not very difi^erent from the general trend of the 

 axes of larger folds in the southeastern part of the quadrangle. 

 The formation is thickest in the western and southern portions, 

 thinning out toward the northeast where it is interbedded with 

 strata of garnet gneiss. A northwestward pitching syncline is 

 suggested at the southeast corner of the area, and it is assumed 

 that the subjacent limestone of the valley is pinched in between 

 the schist and the belt of garnet gneiss which occupies the corres- 

 ponding stratigraphic position at the summit of the east lobe of the 

 hill. The abrupt disappearance of the formation westward is one 

 of its most puzzling features. It is succeeded laterally by a number 

 of detached strips of micaceous and rusty gneiss, one of which, 

 that forming the 620-foot hill reaching to the edge of the sheet, is 

 tucked up and broken off at its northern end, very much in the 

 same manner as the garnet gneiss described later (pages 99, 100). 



The remaining occurrence of quartz schist worthy of notice is 

 that forming the synclinal summit of the small flat-topped hill about 

 a mile due west of Martin's corners, that is, near the west corner 

 of the dotted road one and four-tenths miles northwest of Little 

 River crossroads. This pinched-in outlier of what may have been 

 originally a much more extensive formation, is bounded on the 



