522 Canadian Record of Science. 



the most highly crystalline, while the outbreak of Nephe- 

 line Syenite found at this point is of greater importance 

 than at any other on the mountain, some of it having the 

 appearance of a very fine granite. The specimens from 

 the quarry show some of tlie different forms which are 

 found at this part of the mountain. 



Beyond the quarry the altered limestones occupy all 

 the space between the railway and the points where the 

 mountain begins to rise more abruptly, approximately 

 shown by the narrow black line inside the larger one, the 

 parts which present a rough, craggy appearance being for 

 the most part Theralite, while these limestones usually 

 take the form of a smooth floor or rounded mass, through 

 the erosion which has taken place. 



Where the line crosses the railway, a quarry has been 

 opened, and the altered limestone can there be seen, but 

 covered in places by the ordinary limestone rock, from 

 whirh point to that at which it reaches the Theralite, the 

 distance is about 100 yards, forming an almost level plat- 

 form, cut in different directions by a large number of 

 exceedingly hard, dark colored dykes, frequently cutting^ 

 and crossing each other, and which in many cases rise 

 above the softer limestone, through the latter having been 

 eroded and worn away, apparently by the action of the 

 surf which has left extensive beds of water-worn gravel 

 covering the rock at different points to a considerable 

 depth. 



On theWest-mount, or Little Mountain,what maybecalled 

 the normal limestone completely covers the highest point, 

 which a barometer reading gives as 600 feet, but which, 

 however, has not been otherwise verified, the line passing 

 near the southern limit of the McGill University property, 

 thence past the western end of the reservoir on one side,, 

 and crossing Summit Avenue opposite the gate of Cote 

 des Neiges Cemetery, Fig. 4. 



This space, it will be seen, occupies a comparatively 



