1853.] BIGSBY — GEOLOGY OF QUEBEC. 83 



From Point Levi upwards, the south bank of the river is either a 

 Une of rocky chiFs, or steep earthy slopes overlooking strips of beach. 



The north side of Quebec Basin, although marshy and low about 

 the mouth of the River St. Charles and the Canard iere, rises at the 

 long village of Beauport, and is 300 feet high about the River Mont- 

 morenci, nine miles from Quebec. The land here ascends slowly 

 towards the mountains on the north, which are from five to ten miles 

 distant from the St. Lawrence. 



In order to avoid further detail, I beg to refer the reader to the 

 accompanying map for the other and minor features of this locality. 

 See PL VI. 



General geological notices. — Quebec, with its environs, is placed 

 on the north flank of what we may, for the present, consider the great 

 trough of the St. Lawrence, near a range of high round-topped moun- 

 tains, principally gneissoid, which, coming from the S.W., strike the 

 St. Lawrence twenty-eight miles below Quebec in the massy pro- 

 montory of Cape Tourment, 2200 feet high. 



This trough is bounded on the south, about 100 miles from the 

 St. Lawrence, by a continuation of the Green Mountains of the 

 United States, — not as an unbroken elevation, but as a closely packed 

 series of hills, ridges, and bosses of granite, trap, mica-slate, &c., 

 having a general trend to the N.E. 



Most of the champaigne country of this trough is filled up, for 

 some thousand square miles, with clay-slates, sandstones, conglo- 

 merates, and limestones, chiefly belonging to the " Hudson River 

 Group" of the New York State geologists ; interspersed with ser- 

 pentine and dolomite. All are more or less conformable to the 

 crystalline rocks of the region they occupy, and become metamorphic 

 in the mountain belt itself. In the rough forest plain it is quite 

 common for there unexpectedly to protrude a detached hill, a low 

 knob, or a mere swollen indication, still covered up, of granite or 

 trap, which deranges all the surrounding sedimentary strata. Indeed 

 foldings, curvatures, and dislocations are here very numerous, and 

 are as characteristic of this region as the undisturbed condition of 

 these rocks is of the countries west of Lake Champlain. 



Some of the calcareous rocks of this trough are for very long 

 distances (700 miles N.E. and S.W.) distinctly Upper Silurian, 

 according to Mr. W. E. Logan, to whose skilful investigations, amid 

 hardships and difficulties of every kind, we owe all the geological 

 information we possess of these almost trackless wilds. 



After these preliminary observations we proceed to state, that 

 Quebec with its environs is based on the following series of rocks, 

 beginning from below : — Gneiss, Potsdam Sandstone, Trenton Lime- 

 stone, Utica Slate, and the Hudson River Group of the State of New 

 York. 



On each of these rocks we shall make some general remarks ; and 

 then shall describe minutely a few localities which are to be taken as 

 explanatory types of the district ; — hoping thus to secure some 

 degree both of clearness and brevity. It must be premised, how- 

 ever, that the unnoticed parts also have been carefully examined. 



