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 Brulé, 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 
palzontological 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. IL., 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 
