PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 709 



Green wacke. Marble.] 



No. 1374. GREENWACKE. (Conglomerate.) 



Same place as the last. 



Ref. Annual Report, xvi, pages 97, 123. 



Meg. Rounded, concretionary, or pebble-like masses, from a quarter to a third 

 of an inch in diameter, seen on the weathered surfaces of the same conglomerate. 



Mii: The section is made parallel to the weathered surface. The slide appears, 

 in general, much like that of No. 1372, but is nearly free from calcite. There are 

 variations in the fineness of the grain, and some dark areas of hematite, but the 

 differences are not worthy of special description. The slide seems not to cut any of 

 the round masses that are visible on the weathered surface. It contains, however, 

 several large feldspar fragments. The weathered surface of this rock is shown by 

 figure 12, plate II. One slide. 



Age. Archean (Keewatin). N. H. w. 



No. 1375. GREENWACKE. 



In section 13, adjacent to the above ; in the narrow place between Ogishke Muncie lake and the lake south 

 of Townline lake. 



Ref. Annual Report, xvi, pages 97, 123. 



Meg. Schistosely disintegrating, light green and siliceous condition of the 

 same conglomerate. 



Mic. The slide shows much calcite and coarser grains of feldspar, as well as 

 areas nearly isotropic which were probably of volcanic glass originally. They are 

 now devitrified as in No. 1372. The rock, indeed, must be very near No. 1372 in all 

 respects. One section. 



Age. Archean (Keewatin). N. H. w. 



No. 1378. MARBLE. 



Same place as No. 1375. 



Ref. Annual Report, xvi, pages 97, 123. 



Rusty and calciferous; appears in patches. 



Mir. The slide shows a rock made up like the marble at Ogishke Muncie lake 

 (No. 1371), and like it, and like the sideryte of the Animikie near the west end of 

 Gunflint lake, it contains patches, now coarsely devitrified, which were probably of 

 the nature of volcanic glass when they were deposited in this rock. These indicate 

 some close connection, geographic if not genetic, between the origin of these 

 rocks and the action of volcanic forces. One section. 



Age. Archean (Keewatin). N. H. w. 



No. 1379. GREENWACKE. 



South end of the east bay of Saddle Bags lake on the town line between T. 65-5 and T. 65-6. 

 Ref. Annual Report^xvi, pages 98, 123. 



