ON THE N OUT II WE ST SHORE OP LAKE SUPERIOR. 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 frecpiently 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 clip, 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 east 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 



