

08 The Ottawa Naturalist. 



distance from the eastern outcrop, 75 feet of shale is recorded above 

 the sandstone, which is there, 50 leet in thickness, thus it is probable 

 that these shales were being deposited at the same time as the upper 

 part of the Winnipeg sandstones. The localities at which examples of 

 these sandstones may be seen are, Elk. Island, Black Island, Deer Is- 

 land, Punk Island, the shore from Little Grindstone Point to Grindstone 

 Point, the shores near Bull Head, and the lower part of the cliffs near 

 Dog Head. 



LOWER MOTTLED LIMESTONE. 



Just above the sandstone, horizontal beds of thin bedded mottled 

 limestone form the principle part of the sections at Grindstone Point, 

 Dog Head, Black Bear Island, Tamarack Island., Jack Head Island, 

 and Swampy or Berens Island. The section given by these several 

 exposures amounts to over 70 ft. The lowest beds are those seen at 

 Deer Island and Grindstone Point, capping the sandstone. Immedia- 

 tely above are the beds occuring at Dog Head, followed by the upper 

 part of the Black Bear Island exposure. Those on Tamarack and Jack 

 Head Islands are evidently higher, but belong to the same series, and 

 form, altogether, a section of 65 feet. To the north of this line of 

 section, on Swampy Island and Little Black Island, just to the west, 

 small cliffs of this same mottled limestone occur. The upper part of 

 the cliff on Little Black Island seems to be more fossiliferous than 

 those previously seen, and are probably not represented in the foregoing 

 section, or fill the gap between the Tamarack Island and Jack Head 

 [sland sections. This might possibly add a few feet to the total given 

 there, making a total thickness for this series of 70 feet. The character 

 of the beds in this division is quite uniform and varies only in a slight 

 degree in color. The lowest beds are somewhat darker and contain 

 more earthy impurities, but they all have similar fucoidal markings on 

 the surfaces of beds and through the section dark brownish streaks and 

 blotches of finer grained material. The mass of the rock is made up 

 of the debris of shells, etc., many very badly preserved. At Grindstone 

 Point examples of a large cephalopod, probably a Poterioceras^ have 

 been partially preserved in a vertical position so that frequently slabs of 

 the thin bedded limestone contain sections of the body chamber over 



