CHAPTER V. 



FORMATIONS OF LAKE SUPERIOR. 



As the geology of this portion of the District is treated in detail in the accompany- 

 ing Report of Assistant-Geologist, Dr. Norwood, who was specially charged with the 

 examination of the northern and part of the southern shore of Lake Superior, and 

 as many particulars are also given in the appended observations by Colonel Whittle- 

 sey, as head of the sub-corps which examined the south shore, between the Michigan 

 line and the Bois Brule, I deem it unnecessary, under this head, to subdivide my 

 own remarks as in the previous chapter ; and shall confine them chiefly to a brie 

 review of the much-contested question of 



THE AGE OF THE RED SANDSTONES OF LAKE SUPERIOR. 



Geologists of experience have, until this time, differed widely as to the period to 

 which these sandstones should be assigned. The difficulty rested chiefly in this, that 

 it had been hitherto impossible, in the solution of the question, to apply any decisive 

 palaeontological test. The most diligent search has not yet brought to light, in 

 these sandstones, any fossils, except a few impressions, which are doubtless Fucoides, 

 or fossil sea-weeds. (Tab. I., C, and Tab. II., Figs. 1 and 2.) And this family of 

 marine plants, common to various formations, have a specific character too indefinite 

 to permit their being regarded as trustworthy guides in the identification of strata. 



Some geologists have been of opinion, that these sandstones are of the age of the 

 Old Red or Devonian period ; some, that they belong to the Upper Silurian System, 

 above the Niagara Group of New York ; some, again, that they are the equivalent 

 of the Potsdam Sandstone of the New York Series. Others have stoutly denied 

 this, and have concluded, that they are to be assigned to a period subsequent to the 

 carboniferous ; to the Triasic ; in other words, to the New Red Sandstone Forma- 

 tion.* 



* The late lamented Dr. Houghton, to whose careful examinations of the Lake Superior District, science 

 and the Department were indebted for so much valuable information, seems, as late as 1843 (two years 

 before his death), to have held, as to the red sandstones on the south shore, west of Keweenaw Point, to 



