650 THE GEOLOGY OF MINNESOTA. 



[Conglomerate. Graywacke. Grtvii schist. 



is chloritized. In the slide are a few rounded quartz grains, some sphene and one 

 pebble of red jasper. The feldspathic ingredient, which was originally the most 

 abundant, presents an aspect of general decay. One section. 



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



No. 1065. CONGLOMERATE. 



Same locality as No. 1061. 



Rcf. AnDual Report, xv, pages :i70, :!9(i. 



Met/. Appearing porphyritic by the presence of idiomorphic crystals of feldspar, 

 as in No. 1062. 



Mic. Rounded and subangular quartzes, feblxpar fragments, red jasper, leucoxene, 

 epidote, calcitc. 



TJais slide differs from all the preceding in halving pebbles of d/j/'rri'iif w/.v of 

 /or/,- besides of jasper. These rocks are: fine diabase, wholly altered to a greenstone, 

 but in which the manner of distribution of the feldspathic microliths shows that it 

 was probably an ophitic diabase; and volcanic tuff and porphyry, containing frag- 

 ments of augite, now changed to hornblende, and of feldspar identical with that 

 seen at Kekequabic lake (Nos. 1061, etc.). One section. 



Ai/e. Archean (Upper Keewatin). 



Remark-. The discovery of pebbles of rock in this conglomerate, like the por- 

 phyritic rock of Kekequabic lake, and like the porphyrel of Zeta lake, seems at first 

 view to indicate a later date for the Ogishke conglomerate; but that is not a neces- 

 sary inference, since similar porphyritic pebbles are found in both those other rocks, 

 rather indicating, instead, an identity of origin and age for all of them. N. H. w. 



No. 1066. GRAYWACKE. 



Same locality as No. 1063; N. W. % sec. 27, T. G.V(i; Ogishke Muncie lake. 

 Ref. Annual Report, xv, page 396. 



Meg. Kather quartzose, sometimes pebbly, generally with no signs of bedding. 



Mir. l'\'/tlsjiiir and quartz grains compose this rock essentially. They are 

 frequently angular, the cement consists of the same in a finer state of comminution, 

 of calcite and kaolinic debris. One section. 



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



No. 1067. GREEN SCHIST. 



East side of the second narrows of Ogishke Muncie lake; N. W. }^ sec. 24, T. (i.">- (i. 

 Ref. Annual Report, xv, pages 371, '.VM. 



Mi'!/. Schistose, almost fissile, a part of the conglomerate of the region. 



M/i: There is a banding, evidently due to the occurrence of finer and coarser 

 elements in bedding, which is seen to cross the slide. These bands are also charac- 

 terized by greater or less amounts of a brightly polarizing mineral the nature of 



