242 THE CANADIAN NATURALIST. [Yol. vi. 



mouth of the Trois Pistoles River, that in which the railway 

 cutting has been made, is about one hundred and fifty feet above 

 the level of the sea, and is composed of clay capped with sand 

 and gravel. At no great distance inland, there rises a second 

 terrace one hundred and sixty feet higher than the first, or about 

 three hundred and ten feet above the sea. In some places the 

 front of this terrace is cut into two or more. It consists of clay 

 capped with sand and gravel, with some large stones and Lauren- 

 tian boulders. Still farther inland is a third terrace, the height 

 of which was estimated at four hundred to four hundred and 

 fifty feet. 



In the first mentioned of the above terraces, a very deep rail- 

 way cutting has been made, exposing a thick bod of homogeneous 

 clay of a purplish gray colour and extremely tenacious. It con- 

 tains few fossils; and these, as far as I could ascertain, exclusively 

 Leda trimcata. It is, in short, a typical Leda clay, and its thick- 

 ness in this lower terrace can scarcely be less than one hundred 

 and twenty feet. As the inland terraces are probably also cut 

 out of it, this may be less than half of its maximum depth. 

 Under the Leda clay a typical Boulder-clay had been exposed at 

 one place in digging a mill sluice. It seemed to be about twenty 

 feet thick, and rests on the smoothed edges of the sliales of the 

 Quebec group. 



Though the Leda clay at the Trois Pistoles seems perfectly 

 homogeneous, it shows indications of stratification, and holds a 

 few large Laurentian boulders, which become more numerous in 

 tracing it to the westward. A short distance westward of Trois 

 Pistoles, it is seen to be overlaid by a boulder deposit, in some 

 places consisting of large loose boulders, in others approaching to 

 the character of a true Boulder-clay or associated with stratified 

 sand and gravel. We thus have Boulder-clay below, next Leda 

 clay, and above this a second Boulder drift associated with the 

 Saxicava sand, and aj^parently resting on the terraces cut out of 

 the older clays. This is the arrangement which prevails through- 

 out this part of Canada. It is modified by the greater or less 

 relative thickness of the Boulder-clay and Leda clay, by the 

 irregular distribution of the overlying sands, and by the projec- 

 tion through it of ridges of the underlying rocks. 



The section at Trois Pistoles may be represented as follows in 

 descending order ; 



