16 GEOLOGY OF THE SECOND DISTRICT. 



small part of this valley ; an area of seventy miles by sixty may be taken as its probable ex- 

 tent ; or in other words, it only comprehends three counties, Jefferson, St. Lawrence and 

 Franklin. They form the north and northwestern slope of the valley, which is of an even 

 grade of ascent, and mostly free from abrupt steps, from the St. Lawrence river to the table 

 land of the Racket. The riv6rs draining this slope are Black, Oswegatchie, Indian, De 

 Grasse, Racket, St. Regis and Salmon rivers. They carry down an immense amount of 

 water, but make no perceptible addition to the deep and majestic flood of the St. Lawrence. 

 The remarks already made of the Champlain valley apply to this ; the banks of the St. Law- 

 rence are formed in many places of fractured strata, as those of Lake Champlain ; they sup- 

 port too the same post-tertiary to which allusion has been made ; and it has suffered the kind 

 of abrasion and changes which has resulted in wearing and polishing its rocks. 



The rocks too belong to the Champlain group ; thus, upon the southeastern side, from near 

 Oswego to the north of Quebec, the series rise no higher than the gray sandstone above the 

 Lorrain shales. Primary rocks, as granite and hornblende, compose a part of the Thousand 

 Islands ; but passing those islands to the north, the series of the transition commence with the 

 Potsdam sandstone, and form a continued series up to the grey sandstone, comprehending the 

 Potsdam, Calcifcrous, Birdseye, Trenton, Lorrain shales and grey sandstone. In Lower 

 Canada, in the districts of Missisque, Shefford and Drummond, the talcose slates and lime- 

 stones of the Taconic system prevail, being a continuation of the same rocks as compose the 

 western slope of the Green mountains and the Taconic range. 



On the northwestern side, also, the Champlain group forms the predominant rocks from 

 Kingston to the Falls of Montmorenci. Wliat is remarkable, and well worthy of notice, is 

 the absence of the rocks of the Taconic system upon this side of the river ; the Potsdam 

 sandstone resting upon the primary limestone, gi-anite and serpentine, as in the central part of 

 the county of St. Lawrence. Thus on both sides of the St. Lawrence, in a section passing 

 through (Jouverneur, Black lake, Brockville, to Lyndhurst, Beverly, &c. Upper Canada, the 

 association of rocks is precisely the same on both sides of the river. 



Following down the St. Lawrence, it has been observed that the Champlain group continue 

 to the north of Quebec. But below, from some point not precisely known, the series is car- 

 ried up higher in the transition ; for at the island of Anticosti, the pentamerus lime rock pre- 

 dominates, and bears the same fossil, the Pentamerus galeatus, and with the same general 

 characters as the same rock presents at the foot of the Helderberg. The sandstones, shales 

 and plaster beds of the Ontario group, occur in the islands of the Gulf of St. Lawrence. To 

 the easfis the carboniferous formation of Pictou and Chepody bay in New-Brunswick. The 

 same series of rocks occur therefore to the northeast as at the southwest, thus placing New- 

 York between two coal basins, having within her limits a portion of the series of both. Thus 

 the slope from the Thousand Isles and the Mohawk Valley exhibits the commencement of the 

 rocks, which terminate in the north line of Pennsylvania in the carboniferous rocks ; while 

 those north of the Thousand Isles belong to the coal system of New-Brunswick. This gene- 

 ral view of the topography, phenomena and range of rocks of the great valleys must suffice 



