266 On the Geography and Geology 



stone is very hard, compact, or fine granular, white and yellow ; 

 in slabs and angular thick masses, frequently weighing a quarter 

 of a ton. It is crowded with various forms of productse, turbos, 

 orthoceratites, turbinolia, triiobites, S^c, 8fc. From their very 

 frequent occurrence, great dimensions and angular shape, I believe 

 them to be very near their parent rock. 



In the description of the rock formations of Lake Superior I, 

 perhaps, have used too great minuteness ; but, in the present state 

 of geology, it is the safer error ; and, especially, as regards these 

 distant and melancholy wilds, whose few visitors are only anxious 

 to escape from them. 



The rocks of Lake Superior are few in number^ when compared 

 with those of a similar extent of country in Europe ; but those 

 few are on an immense scale. Of mica-slate, clay-slate, 8fc., there 

 is not a vestige ; not even in debris ; nor of any of the nu- 

 merous secondary deposits above the mountain limestone. Sand- 

 stone, under various modifications, occupies the greatest space ; 

 in intimate connexion with the next prevailing rocks, the amyg- 

 daloids, porphyries, and greenstone trap. The alternating granites 

 and greenstones of the north-eastern and eastern coasts, are 

 nearly equal in quantity to these. The last-mentioned rocks, 

 including the sienite of the Peek are the oldest, and seem to be of 

 the same age, and to belong to the transition class, or to the 

 youngest of the primitive. I have fixed upon this epoch from the 

 iremarkable proportion of hornblende in the granite, and its being, 

 in one instance, replaced by chlorite earth ; from the plentiful 

 occurrence of calcspar, the interstratification of conglomerate, true 

 and simulated, in the greenstone of Michipicoton, the great num- 

 bers of trappose veins traversing all the formations indifferently, 

 and, finally, from the passage (if I be therein correct, as I believe 

 myself to be) of the Huggewong granite into amygdaloid. These 

 granites and sienite are not stratified, but the greenstones interposed 

 in such vast masses, with an eastern (or EbN.) direction, and a 

 vertical or northerly dip, indicate the order of deposition and its 

 breadth. On the old route from Lake Superior to the Lake of the 

 Woods, this alternation of chloritic greenstone and amphibolic 



