and 3 marks the division between the trap and the unaltered limestone, the part covered by the latter being shown by the space below the line, the Theralite by the perpendicular lines, the altered limestone by the dotted shading, and the crosses indicating Nepheline Syenite.

On the map, Fig. 4, the shaded portion enclosed by the heavy black line shows the position and general appearance of the part occupied by the trap and altered limestone, as referred to above.

This part of the mountain as shown on the map is also an irregular oval, with a length of about 9,000 feet from East to West, by 5,700 in width, and having an approximate area of from 1,000 to 1,200 acres. This is somewhat larger than that estimated by Logan, Geology of Canada, p. 172, which he placed at about 700 acres.

The

On the map, Fig. 4, it will be noted that the margin of the dark portion is dotted, while the central part, with a slight exception, is shaded in black. former is principally altered crystalline limestone, with several heavy bands of Nepheline Syenite, marked by crosses, while the black represents the Theralite, which forms the great mass of the mountain.

From the map, Fig. 4, it will be seen that the crystalline limestone is found at the margin, almost completely encircling the area occupied by the trap. Besides this, there are a few small, isolated patches near the Park Ranger's house, and it is also found extending across the lowest part of Mount Royal Cemetery, in the direction of the Westmount outcrop, but it can only be traced where excavations have been made, owing to a heavy covering of drift.

At the northern end of the mountain, the altered limestone passes in several places under the road near the Incline Railway, where it is 410 feet above the river. Further south, the Syenite appears at one point beyond the look-out, while on Westmount almost the whole of

the mountain included in the dotted shading is occupied by the altered limestone, the trap formation being represented by some heavy bands of Theralite, alternated by others of Syenite, of which there is also a small exposure further to the south, and shown by crosses at the point A outside the black line.

On the south and west sides, where the broken lines are shown, the rock is deeply covered with drift, and the line is consequently drawn to connect the nearest points. where the formation can be seen.

Beginning with the sketch Fig. 1, which shows the easterly side of the mountain, we have the view which is the most familiar. The black line showing the limit of the limestone, it will be seen, reaches well up to the top of the mountain. At a point near the centre of the sketch, a short distance to the east of Cote des Neiges road, this line reaches the summit, the height being about 660 feet above low water in the harbor.

From this point it runs in an easterly direction, passing below the look-out, where it is about 560 feet above the harbor, until it reaches the natural look-out point above

the high level reservoir, where it is 590 feet above the river.

A short distance to the south of this point there is an isolated patch of Utica shale, resting against the trap outside the black line on Fig. 4.

The summit of the mountain at the Observatory is 739 feet above the river, which would give a height of about 150 feet for the trap above the line of the limestone. These measurements may be considered as accurate, as they are taken from the plan in the Road Department of the city, but the line being fixed by local points, such as

the look-out, roads or other marks, its location must necessarily be approximate, but sufficiently accurate to show its general position.

Passing towards the northern end of the mountain, the altered crystalline limestone is exposed in several places where the rock has been removed in making the road, its position being shown by the dotted shading on Fig. 1.

Fig. 2 shows the northern end of the mountain from a point near the Incline Railway to the Mount Royal Cemetery gate. This part, especially that near the

Incline Railway, which includes the bold, almost perpendicular bluff, is encumbered by large blocks of Theralite. to such an extent that it is difficult to determine the limits of the different formations, but at least a fairly approximate idea can be formed as to their position from the exposures which can be seen at different points.

Here the altered limestone is also found exposed at different places, and towards the Cemetery it reaches well up to the top of the mountain, from which point it appears to extend across the Cemetery in the direction of Westmount.

From the Cemetery gate, the division between the two formations runs in almost a direct line past Outremont Quarry, to a point near Cote des Neiges, where it crosses the Electric Railway, Fig. 3, and then re-crossing it in the direction of Westmount, passes under a heavy deposit of drift, by which it is concealed until it re-appears at the foot of the West-mount, or the Little Mountain.

From the Mount Royal Cemetery gate to Westmount there is a continuous and extensive exposure of altered limestone, that found in the Outremont Quarry being

the most highly crystalline, while the outbreak of Nepheline 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 the 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 which point to that at which it reaches the Theralite, the distance is about 100 yards, forming an almost level platform, 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 the West-mount, or Little Mountain,what may be called 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