PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 369 



Quartz. Red shale. Conglomerate.] 



This rock was analyzed chemically by Prof. J. A. Dodge, with the following result (Final Report, vol. i, 

 page 202): 



SiO 2 78.24 



A1 8 O 3 10.88 



Fe 2 0, / 



FeO ) 



CaO .95 



MgO 1.60 



K 2 O 1.67 



Na 2 O .06 



Total 97.23 



Two sections. 



Age. Cambrian (i. e., "Upper" Cambrian). 



Remark. This light-colored rock is only a phase in the red sandrock of the 

 region, and constitutes only a subordinate part of it. Other samples collected are 

 red, but spotted with gray, these gray spots much resembling the rock of the above 

 description. N. H. w. 



No. 443 A. QUARTZ. (Pebble in sandstone.) 



Same locality as No. 443. 



Ref. Annual Report, x, pages 9, 30. 



Meg. A roughly egg-shaped, well-rounded quartz pebble, nearly three inches 

 long, is contained in red sandstone similar to the red portion of No. 443. There are 

 also pebbles of a soft red shale and one pebble of a fine-grained, brownish, soft rock 

 whose nature is not evident. 



No section. 



Age. Cambrian (i. e., " Upper" Cambrian). u. s. G. 



No. 444. RED SHALE. 



About the centre of S. W. % sec - 6, T. 48-15 W., near Fond du Lac. Here a bed of dark-red shale strikes 

 across the bluff. This is about eighteen feet thick, and has thin beds of sandstone occasionally. This shale has 

 spots that are greenish. 



Ref. Annual Report, x, pages 9, 30. 



Meg. A fine-grained, soft, red shale. Two small circular spots, less than one- 

 tenth of an inch in diameter, occur. These are greenish gray in color, and except for 

 the color seem to be the same as the rest of the rock. The rock contains many 

 minute glistening flakes of a micaceous mineral. 



No section. 



Age. Cambrian (i. e., " Upper " Cambrian). u. s. o. 



No. 445. CONGLOMERATE. (Fine, red. ) 



Near the centre of sec. 1, T. 48-16 W., valley of the St. Louis, above Fond du Lac. 



Ref. Annual Report, x, page 10 (No. 2 of the section); Annual Report, xxiii, page 239. (Compare No. 1976. 

 which is a collection of pebbles from this conglomerate.) 



Meg. A rather fragile conglomerate consisting of Keweenawan and Keewatin 

 debris and of quartz sand. 



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