623 THE GEOLOGY OF MINNESOTA. 



[Tuff. Greenstone. Caloiteand pyrite. 



No. 1004. TUFF. 



From the bluff, centre of sec. 19, T. 63-11; west from Kawasachong falls. 

 Ref. Annual Report, xv, pages 320-322, 325, 393. 



Meg. Fissile schist, lenticularly disintegrating, confused, near the water, 

 underlying the next. 



Mir. Rather fine-grained, in general consisting largely of chlorite iu elongated 

 patches and fine mesh-work. Through this fine mass are distributed numerous 

 coarse angular grains of quartz, leucoxene and of striated feldspar, and indistinct 

 rounded pieces of rock of differing granular aspect and slightly differing composition; 

 the last, however, being uniformly fine grained and allied in general to the main 

 rock itself. 



Age. Archean (Lower Keewatin). 



Remark. This rock, although its coarser grains are sharply angular, was probably 

 accumulated beneath the ocean, and it would correctly be styled submarine tuff. 



N. H. w. 

 No. 1005. TUFF. 



Same place as the last but overlying it. 



Ref. Annual Report, xv, pages 320, 322, 325, 393. 



Meg. Resembling the rock of Kawasachong falls. 



Mic. Finely granular, rather homogeneous, containing much quartz in minute 

 angular grains and crossed by small veins of quartz and calcite. Evidently a finer- 

 grained condition of rock like the last. 



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



NO. 1006. "GREENSTONE.'' 



South shore of Fall lake; N. E. % sec. 19, T. 63-11 W. Schist near the dike No. 1009. 

 Ref. Annual Report, xv, pages 322, 323, 393. 



Mi>g. One of the fine-grained, roughly schistose "greenstones." This specimen 

 contains some pyrite. No section. 



Age. Archean (Lower Keewatin). u. s. G. 



No. 1007. CALCITE AND PYRITE. 



Same localit'y as No. 1006. In contact with No. 1006. 

 Ref. Annual Report, xv, pages 322, 323, 393. 



Meg. A small mass of fine-grained, granular calcite, with considerable dissem- 

 inated pyrite. No section. 



Age. Archean (Lower Keewatin). u. s. G. 



NO. 1008. "GREENSTONE." 



Same locality as No. 100G. Obtained two feet from the dike, on the south side. 

 Ref. Annual Report, xv, pages 322, 323, 393. 



Meg. Very similar to No. 1006. No section. 



Aye. Archean (Keewatiu). u. s. G. 



