182 SOME NOVA SCOTIAN ILLUSTRATIONS 



II. GLACIAL TROUGHS. 



It is probable that most observers are familiar with glacial 

 markings or striations, the scores left by the great ice-sheet of 

 the Glacial Period in the course of its movement southward, and 

 which are abundantly exhibited in the Park and elsewhere- 

 about the City of Halifax. Bub probably few, if any, have seen 

 such a proof of the power of ice action to carve the surface over 

 which it moves as is afforded in the photographic plate No. DC 

 This remarkable view was taken on Lockeport Island, within, 

 ten or fifteen minutes walk of the town of Lockeport. The 

 rocks at the place are Cambrian slates and quartzites, the latter 

 predominating, in beds 10 to 15 feet in thickness, and dipping 

 south-easterly at an angle of about 50. The trough, which is. 

 plainly shown in the picture, runs in the direction of the beds,, 

 and, no doubt, owes its origin in part to that fact, and to the 

 unequal hardness of the two kinds of rocks which the strata 

 contain ; but even with all allowance for such favoring circum- 

 stances, the magnitude of the result is not only unusual but 

 phenomenal. Not having any means of exact measurement ats 

 hand, the writer is unable to give precise data as to the dimen- 

 sions of the trough, but is safe in saying that its length was at 

 least 30 feet, its depth at centre at least 4 feet, and its breadth 

 as much as 4 or 5 feet, the larger part being in massive quartzite.. 

 The form of the trough, as seen in the view, was in section not 

 unlike that of a canoe, the sides curving gracefully down to the- 

 middle line, while ; along the same sides arid parallel with the axis, 

 of the trough, were numerous striations of the ordinary kind, also 

 clearly seen in the photograph, and leaving no doubt as to the 

 nature of the agent to which the trough itself is to be ascribed. 



A trough of such magnitude, due to glacial erosion, is, 

 certainly a very unusual occurrence, at least in this part of the 

 world ; but, remarkable as it is, it in turn sinks into insignifi- 

 cance in comparison with some other troughs, due to the same 

 agency, which \vere subsquently seen. These occur about mid- 

 way between Port-la-Tour and Baccaro, on the coast of Shelburne 

 County, and upon a small point, which is almost an island,. 



