THE PRECAMBRIAN ROCKS OF THE CANTON QUADRANGLE 3 1 



In the latter case (see figure 3) the rock in question is a gar- 

 netiferous amphiboHte. Its contact with the granite gneiss is hidden 

 in the bed of a small brook whose position is indicated by the re- 

 entrant contours on the map at this point, but the formation extends 

 along the edge of the granite for about one-fourth of a mile west- 

 ward, in which direction, however, it loses its garnetiferous char- 

 acter. Its contact metamorphic nature is strongly suggested, espe- 

 cially on the right bank of the brook, by its upward gradation into 

 an impure thin-bedded limestone, and by the mineralogical compo- 

 sition of the rock itself. A thin section reveals abundant skeletal 

 garnet, together with augite (in part diallage), accompanied by 

 andesine, secondary green hornblende, and a small amount of 

 orthoclase. Magnetite, apatite and pyrite are not abundant acces- 

 sories, and secondary calcite is noted. No scapolite is observed, 

 such as characterizes the intermediate stage of alteration of lime- 

 stone into amphibolite in the Haliburton-Bancroft area (Adams and 

 Barlow, 1910, pages 102-6). 



At the second locality mentioned, the Woodcock's rapids occur- 

 rence, three members of the contact series are present; these in 

 order from below^ upv/ard are garnetiferous amphibolite schist, black 

 amphibolite and granite gneiss. The schists dip westward under the 

 granite, which surmounts the section (see figure 4). Limestone, 



a 





b 





c 





d 





e 



^1 ^( ^^ ^ / •>. 





^^^ 









3=^ 







Fig. 4 Cross-section of lower granite contact. A good example of con- 

 tact alteration and marginal injection. (a) Pink granite gneiss holding 

 xenoliths of (b), black amphibolite, which in turn is soaked and injected by 

 granitic and pegmatitic material; scapolite alteration common; (c) garnetif- 

 erous biotitic and hornblendic schist, probably underlain by (d), crystalline 

 limestone, of which (b) and (c) are regarded as progressive contact pro- 

 ducts. Section about 25 feet thick from top of talus and drift, (e). 



Three and seven-tenths miles south of Canton village bench mark, left 

 bank. 



