656 THE GEOLOGY OP MINNESOTA. 



[Slate. Conglomerate. 



Mic. There are but few grains of quartz in the slide, but there are many frag- 

 ments of hornblende and of feldspar, as well as some pebbles of rocks in which these 

 crystals appear. The whole rock appears to be a volcanic tuff or a debris from quartz- 

 porphyry and other Lower Keewatin rocks. It is similar to the rock No. 1080, but 

 finer grained. One section. 



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



No. 1083. SLATE. ( Green-black, flinty. ) 



From the hill, same locality. 



Ref. Annual Report, xv, pages 375, 397. 



Meg. Resembles a fine, flinty basalt, intersecting No. 1082. 



Mic. The slide consists largely of chlorite, spicules of actinolitc, feldspar, and 

 roundish scattered grains, apparently of epidote, which are sometimes grouped into 

 grains of larger size. These larger grains have a high single and also double refrac- 

 tion. There is a small amount of fine quartz in angular grains. One section. 



Aye. Archean (Upper Keewatin). 



Scmark. This rock is evidently a clastic one. N. n. \v. 



No. 10*4. CONGLOMERATE. (Fine.) 



Sec. 22, T. 65-6. Same locality as No. 1082. 

 Ref. Annual Report, xv, pages 375, 397. 



Meg. Fragmental rock from the dark-green beds represented by No. 1082. 



Mic. Highly angular, gritty, with quartz and feldspar. The rock is a fail- 

 sample of the finer portions of the Ogishke conglomerate. There are many fine- 

 grained fragments, apparently of the matrix of a quartz-porphyry and of feldx/Kti' 

 and of hornblende. Some parts appear to be wholly micro-granulitized feldspars. It 

 is apparent that the elements of this rock were much decayed before they entered 

 into the constitution of a rock mass, but were not long exposed to sedimentary 

 attrition. One section. 



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



No. 1085. CONGLOMERATE. 



West end of Little Reynard lake, near the water ; sec. 26, T. 65-6. 

 Ref. Annual Report, xv, pages 3T5, 397. 



Meg. Evidently a coarse fragmental. 



Mic. The slide is quite varied in its aspects. With conspicuous angular and 

 subrounded quartz grains are many pebbles of a very fine-grained earlier fragmental 

 rock, of old, now much decayed, twinned feldspars, and apparently of an older 

 diabasic rock (judging from a suggestion of the ophitic structure still remaining). 

 These are embraced in a greenish, finer matrix which is debris probably from some 

 basic rock, the whole liberally sprinkled with calcite and a little pyrite. One section. 



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



