ON THE NORTHWEST SHORE OF LAKE SUPERLOR. 397 
Pigeon River to Grand Portage Bay (and thence send some of the voyageurs across 
by land, with provisions, while you followed, on foot, the course of Pigeon River, 
from its mouth up), I herewith submit the following 
REPORT. 
Pigeon Cape, or Point, is formed by a trappean upheaval, the products of which 
have flowed, apparently, from fissures, having a strike or bearing usually somewhat 
north of east. It is not, however, a continuation of the nearest main trap ridge, 
the peak of which, rising a short distance northeast from the interior of Grand 
Portage Bay, you directed me, on a former occasion, to measure barometrically, and 
which I found to be six hundred and thirty-four feet high. That range, as you 
afterwards found, bears northeast and southwest, and forms the falls of Pigeon 
River, about a mile and a half from the “ Mission,” and is there two hundred and 
twelve feet wide. 
The trap ridge constituting Pigeon Point, has withstood the wearing effects of 
time and the action of the water; and has formed, in conjunction with the slates, 
through which it frequently cuts, a strip of land, usually about half a mile wide, 
which stretches nearly four miles in length, from the mouth of Pigeon River, the 
latter flowing out on its north side. About three miles from the mouth of the 
river, where the trap range is partially interrupted, there is low shingle beach, ex- 
tending across the peninsula, which here is only from two hundred to two hundred 
and twenty-five feet in width, and six feet above the lake-level of that year (1849). 
At this point, in a short time, no doubt, the shingle beach will disappear, shortening 
the cape about a mile, and leaving an island, similar to those found so abundantly 
in the Lake, in a bearing continuous from some of the numerous trap ridges or 
dikes of the north shore. 
The above greenstone trap ridge has, on both sides, cut through slates, altering 
them, in many cases, considerably, and giving them a general dip, from the disturb- 
ing cause, of from 15° to 40°: about 40° south-southeast, near the extreme point of 
the cape, on its south shore, and northerly on its north shore; while the angle of 
dip is usually only from 15° to 18°, south-southeast, when the distance from the 
disturbing cause is greater, as it is at the points forming the cast end of Grand 
Portage Bay. ' 
This point consists of a southern spur from the main trap ridge, and is formed, 
apparently, by a lateral overflow. Where it terminates in the Lake, this sheet of 
ancient submarine lava seems to have flowed perpendicularly over the ends of the 
shaly rocks. 
Near this point, the rocks are about ten feet above the Lake, and although some- 
what aluminous, are more siliceous than those on the north side of Pigeon Cape, 
where the argillaceous character predominates: some, indeed, appear to be altered 
sandstones. 
In addition to the greenstone ridge, there are several dikes on the peninsula, 
some having a nearly east-and-west direction, while others bear nearly north and 
south. 
They vary in width from fifteen to twenty feet, and produce sometimes great 
