4:6 Dresser — Contribution to the Geology of Quebec. 



ing the hanging wall of the Clark mine was probably closely 

 allied to the quartz-porphyry in its original composition. It 

 rather closely resembles a specimen of " sheared felsite " from 

 the Gettysburg Railway, south of Clermont House, Monterey, 

 Pennsylvania, seen in the petrographical collection of McGill 

 University."^ 



A greenish gray fine- textured massive rock is of large 

 extent, especially in the southern part of this belt. In the 

 thin section quartz is found in broken phenocrysts and also in 

 smaller grains, presumably primary, in the rather fine holo- 

 crystalline groundmass. Under high power (x220) feldspar 

 appears in the groundmass in small lath-shaped individuals 

 which extinguish at low angles with the principal axes. Epi 

 dote and chlorite are abundant representatives of primary 

 bisilicates. The rock would have originally been about of the 

 character of a quartz porphyrite. 



A. large part of the central and southern portions of this 

 belt in the township of Ascot is occupied by a highly foliated 

 rock of green color and massive appearance. Under the 

 microscope a little feldspar is found in an aggregate of color- 

 less hornblende, chlorite, epidote, dolomite and sericite, all of 

 which are secondary constituents. 



This rock agrees essentially with the sheared greenstone 

 from Jack's Mountain tunnel, near Monterey, Pennsylvania, as 

 seen in the McGill University collection. 



A similar but more dolomitized rock occurs in various parts of 

 the belt, one occurrence of which is niapped as igneous on the 

 map to accompany the Annual Report of the Geological Sur- 

 vey of Canada for 1886. 



These rocks, though probably of several different ages of 

 eruption, are generally much metamorphosed. But cutting them 

 there are dikes of camptonite and olivine diabase, which are 

 quite undisturbed in position and comparatively little altered 

 in mineralogical composition. They also cut the Lower Tren- 

 ton strata along the edges of the belt, while these overlie 

 the other igneous rocks of the region. Whence it appears 

 that the Stoke Mountain, or Ascot belt, has been the scene 

 of volcanic activity at various periods through a long range 

 of time, from pre-Cambrian to post-Trenton. A brief notice 

 of the lithological character of those rocks has been recently 

 given bj the writer in a communication upon the copper- 

 bearing rocks of the area,f and their general agreement in 

 extent with the pre-Cambrian of the Geological Survey Map 

 of 1886 pointed out. 



* Bulletin U. S. Geological Survey, No. 136, ** Ancient Volcanic Eocks 

 of South Mountain, Pennsylvania," by F. Bascom, 

 f Trans. Can. Min. Inst., Montreal, March, 1902. 



