74 . Dr. C. T. Jackson on the f 
_seem to prove that the sandstone is above the Silurion limeatalas 
‘and consequently that it is either the old or the new red. The | 
absence of fossil shells in the sandstone would lead us to con- . 
- elude that it does not belong to the old red, and consequently we 
are led back to my original opinion, as published i in the American | 
Journal of Science, in 1845, that the Lake Superior sandstone is — 
of a later date, and is probably the new red. 
This opinion was also expressed by Monsieur De Verneuil, dur- , 
ing his visit to the Lake in 1846, but I do not know from what 
** 
data his opinion was formed. It has been asserted that the Lake . 
Superior sandstones pass beneath the Silurian rocks, but Ido not 
think the fact has ever been observed. 
Isle Royale.—This island is situated on the north side of Lake 
Superior, in latitude 48° North, longitude 89° West. It is about 
forty miles in length, and five or six miles wide. It presents a 
broken and rugged outline on its coast and is deeply indented by 
long and narrow inlets and bays, all of which are parallel to the 
ranges of the trap rocks which constitute the ridges traversing 
the island throughout its length. Several small lakes are also 
seen lying between the trappean hills and coinciding with their 
line of bearing. 
The general direction of this island is parallel to that of Ke- 
weenaw Point, and the trap rocks are of the same geological age 
and have uplifted the sandstones of the same epoch. 
On the southwestern end of the island the fine red sandstone 
strata are seeu near Card’s Point, and they extend along the coast 
of Siskawit Bay to Epidote Cove, forming gently sloping sheets 
extending out into the lake toa considerable distance. Conglom- 
erate rocks border the coast nearly to Rock Harbor and lie next 
to the trap. The inland boundary of the sandstone was ascer- 
tained by my sub-agents to be parallel to the coast line where it 
is exposed. About one-fourth the area of the island is sandstone 
and conglomerate rock. All the rest of it consists of trap, which 
forms ridges attaining an elevation of from three hundred to five 
hundred feet above the lake, and extending in a saps line 
throughout the whole extent of the island. In some places iso- 
lated masses of trap rocks form tall towers minding like high 
chimneys on the hill sides; in others, picturesque islands covered 
with dark spruce trees are seen jutting out on the coast, or stand- 
ing like watch towers at the entrance of the harbors. 
sle Royale was better known to the Indians as a good place 
for catching Siskawit than asa mining region ; and it is probable 
that the name Menung, signitying a good place, re refers to the 
fisheries, but it is certain from the “ Relacions” of the Jesuit fath- 
ers, that they were aware of pe existence of an abundance of 
copper boulders upon its shores. 
