76 LAKE SUPERIOR. 



tures, being changed into sienite or porphyry, or into rock partaking in 

 various degrees of the characters of both, by the influence of large veins of 

 melted materials. Metallic veins are sometimes formed in the same way, 

 by injection, and they also in the same manner modify the surrounding rock, 

 as in the instance before us. Sometimes, also, they are formed by sublima- 

 tion into crevices, or by electro-magnetic action, causing an interchange of 

 particles between various parts of the rock." 



July 16^/i. Early this forenoon the Island of St. Ignace ap- 

 peared looming up in the distance. We passed the " Petits 

 Ecrits," a rock ornamented with representations of various ani- 

 mals, canoes full of men, &c., together with various fabulous mon- 

 sters, such as snakes with wings, and the like, cut out of the 

 lichens ; the work of the Indians, or perhaps of stray miners or search- 

 ers for copper, who, as appeared by dates and initials, have adopted 

 from them this mode of attracting the -attention of the passer-by. 

 These pictures were of various dates, as was shown by the various de- 

 grees of distinctness, as the rock was either quite laid bare, or the black 

 lichens had more or less completely recovered possession of it. We 

 now entered the vast archipelago of islands occupying the whole 

 N. W. corner of the lake, as far as Pigeon River, a distance of about 

 two and a half degrees of longitude, viz. : from 87 30 ' to 90 "W. 

 It is difficult to convey any notion of the vast number of islets and 

 rocks in this part of the lake. Capt. Bay field in his (unpublished) 

 chart of Lake Huron, is said to have laid down thirty-six thousand 

 islands, on twenty thousand of which he has landed ; the number in 

 Lake Superior cannot, I should suppose, fall much short of this. In 

 both lakes the islands lie almost exclusively along the northern and 

 eastern shores. In Lake Superior, with the exception of the group 

 called the Apostle's Islands, there are very few islands on the south 

 shore, or on the north-west shore beyond Pigeon River. In Lake 

 Huron there is scarcely an island outside the Georgian Bay, and in 

 the lower lakes islands are almost entirely wanting. 



As we were passing under an overhanging cliff where nests of the 

 barn-swallow were niched into the rock within reach of the hand, 

 an Indian in his canoe with his squaw and child suddenly glided 

 alongside from some cove, and offered fish in exchange for tobacco. 



