304 P. Chalmers — Pleistocene Marine Shore-Lines 



beneath in places. The height of its surface above the sea 

 varies from a few feet to live hundred feet or more ; but the 

 average height does not exceed two hundred and fifty to three 

 hundred feet. As stated already, it is traversed by ridges, espe- 

 cially near the base of the Notre Dame Range, where the plain 

 is usually highest. To the southeast of Ste. Julie and Somerset 

 stations, Grand Trunk Railway, the border of the marine plain, 

 at the foot of the mountains, was found to be about 600 feet 

 in height. From this point it slopes away gently to the 

 northeast, north and northwest, and it would seem as if the 

 margin here must have received a somewhat greater differen- 

 tial uplift than other parts in the vicinity. A number of facts, 

 which cannot be given in detail, lend support to the view that 

 this local uplift, the axis of which is, perhaps, transverse to 

 the general trend of the mountain range, i. e. approximately in a 

 southeast and northwest direction, was of slightly greater- 

 extent here than to the eastward. But the forces producing 

 the general Pleistocene upheaval seem also to have effected 

 similar local deformations in other places in the region on the 

 south side of the St. Lawrence River. 



From the foregoing facts, therefore, it will be seen that the 

 topographical and physical features of the region described 

 are such as w r ould be likely to favor the formation of terraces 

 or beaches along the shore of the Pleistocene sea which occu- 

 pied the St. Lawrence Valley. 



Along the inner border of the marine plain the terraces and 

 beaches representing the upper limit of the subsidence, and 

 showing the ^extent of the subsequent upheaval, are to be 

 found. In most places they consist of a series of two, three,. 

 or more, and are usually formed of stratified, water-worn mate- 

 rials with bowlder-clay beneath. Sometimes they retain their 

 original outlines continuously for considerable distances ; in 

 other cases they are broken and denuded. The lower terraces 

 are always best preserved. Occasionally we find a terrace or 

 water-line cut into the bowlder-clay ; but as a rule the beaches 

 partake largely of the character of those formed along the coasts 

 at the present day. 



Highest Pleistocene Shore-lines. — Commencing with the 

 beach at Gaspe" Bay, we shall proceed westward along the south 

 side of the St. Lawrence River. A considerable gap lies 

 between Gaspe and Ste. Flavie, where I have not yet been able 

 to make the necessary levellings. With this exception the 

 observations form a connected series along the north side of 

 the Notre Dame Range as far west as Somerset station, Grand 

 Trunk Railway. From Somerset or Arthabaska westward to 

 the International boundary the beaches have not yet been 

 traced along the north side of the mountains. 



