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 rivers 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, Calciferous, 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. What 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, granite 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 Gouverneur, 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 east is 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 
