. Travels in North America, in the years 1841-2; with geological observations on the United States, Canada, and Nova Scotia. minates in two summits,one considerably higher than the other, and capped,as before stated, with a mass of greenstone abouteighty feet thick. The subjacent beds of Silurianlimestone are traversed by dykes and veins of the base of the hill, on its eastern side, in thesuburbs of Montreal, we find clay and sand (<?/, p,fig. 13) above 100 feet deep, in which marine shellsoccur. This deposit forms a terrace which endsabruptly in the steep bank (e) facing the river-
. Travels in North America, in the years 1841-2; with geological observations on the United States, Canada, and Nova Scotia. minates in two summits,one considerably higher than the other, and capped,as before stated, with a mass of greenstone abouteighty feet thick. The subjacent beds of Silurianlimestone are traversed by dykes and veins of the base of the hill, on its eastern side, in thesuburbs of Montreal, we find clay and sand (<?/, p,fig. 13) above 100 feet deep, in which marine shellsoccur. This deposit forms a terrace which endsabruptly in the steep bank (e) facing the river-jilain,and running parallel to it for three or four miles. Chap. XXII. mountain of Montreal. 117 It varies in height from 50 to 150 feet, and at itsbase is a low tlat of more modern gravel (/), risingfrom ten to twenty feet above the St. Lawrence. Incertain places, as at the Cote St. Pierre, on the roadfrom Montreal to Lachine, the surface of the terraceslopes from e to d, or towards the mountain. A goodsection of this modern deposit was to be seen at theTanneries, a village in the parish of St. Henri in the Fig. Section of Montreal mountain, with shelly drift at its base. A. Silurian limestone. B. Trap or greenstone. c. Dykes of basaltic trap. d. Dyke of felspathic trap, or e. Terrace of drift with shells. /. Gravel, on which part of Montreal River St. Lawrence. suburbs of Montreal, at the time of my visit (June,1842). Excavations had recently been made for anew road, exposing horizontal beds of loam andmarly clay, in one of which, at the height of aboutsixty feet above the St. Lawrence, I observed greatnumbers of the Mytilus edulis, or our common Euro-pean mussel, the shells retaining both valves andtheir purple colour. In the same beds were speci-mens of Tellina grcEnlandica, and a few of Saxicava 118 (;nT OF < dkut Chap, xxh, rvsrosa. In the midst of the shells, I found a singleisolated boulder of gneiss, six inches in diam
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