168 



THE GEOLOGIST. 



rock (composed of the Niagara limestone), wliicli projects into tlie 

 lake from the lofty island which bears their name. On other parts of 

 the coast the rock is still wearing away by the action of the waves 

 into the same remarkable pillar-like shapes. Those which at present 

 exist have been formed in a similar manner to the Flower Pots on 

 the Mergan Islands, and the " Old Woman" of Graspe, having at one 

 time constituted caverns, as I have already described. 



10. — Peefoeations and Caverns of Michilimacinac Island, Lake 



HUEON. 



The Island of Michilimacinac is sitnated near the straits of the 

 same name, at the north-western part of Lake Huron, and is com- 

 posed of gypsiferons limestone and rocks belonging to the Onondaga 

 salt gronp of the American geologists. It is a hundred and fifty 

 feet in height, and its precipitous cliffs are broken into a number of 

 shallow and deep caverns by the action of the waves. One of these 

 perforates a projecting point of rock near its south-east angle, and 

 the general appearance of the coast is not dissimilar to that of the 

 Pictured Rocks, presently to be described, only that they are not on 

 such an extensive and grand scale. Besides these caverns, produced 

 by aqueous agency, three objects of natural curiosity, are visited by 

 strangers in this island — they are the Giant's Arch, the T^atural 

 Pyramid, or Sugar Loaf Hock, and the Skull Hock. The last of 

 these is noted for the presence of a cavern, which would appear at 

 one time to have been a place of ancient Indian sepulture, as num- 

 bers of human bones were discovered ^vithin it, and are even now 

 observed laying about its mouth. The entrance to the cavern is low 

 and narrow, but its dimensions are not very considerable. It pos- 

 sesses some historical interest for Canadians, from the fact that it 

 was in this cavern that Alex. Henry was secreted by a fi'iendly 

 Indian after the massacre of the British garrison at Old ]\Iichili- 

 macinac, in 1763.* 



11. — The Pictueed Rocks, Lake Supeeioe. 



These are included in the present paper, although in the ten'itory 

 of the United States, because they were celebrated among the French 

 Voyageurs, who gave them the name of Les Portailles. The 

 Pictured Rocks (as they are now best kno^vn) continue for twelve 

 miles along the south coast of Lake Superior, about eighty miles 

 west of ^Yhite Fish Point. They consist of a series of lofty cliffs, 

 varing in height, but mostly of three hundi'ed feet, and are com- 

 posed of horizontal stratified layers of grey sandstone, weathering of 

 difiorout tints, which arc the equivalent of the Potsdam sandstone, 

 a white quartz rock, probably overlaid here in some places by the 

 calciferous sandstone. All along this coast the fmy of the waves, 



* See Henry's Travels and Adventm-es. 



