SURFACE GEOLOGY, PICTOU COAL FIELD—POOLE. 391 
Brook fault,—that great dislocation* of some 2600 feet which 
separates the Westville from the Albion field, and down tilts the 
former in the direction of the latter. 
The influence of this fault on the surface configuration still 
remains, on the one hand a uniform slope towards it, on the other 
ranges of low hills abrubtly terminating against it. 
In the pre-glacial stage of its existence, the brook doubtless 
flowed at a lower level than at present over part of its course, 
and as erosion proceeded, and influenced by the inclined strata 
on the one side, it pressed eastward against the broken measures 
of the fault, or crossed over and skirted the Albion section. 
After the deposition of the glacial drift ceased, and the brook 
renewed its existence, and in part guided by the form of the 
ridges already referred to, and partly by the general trend of the 
old contour not entirely obliterated by the new coating it had 
received, it began again its work of erosion at a higher level than 
at which it left off, and it traversed almost, if not altogether, on 
the eastern side of the fault in question. To what extent the 
fault and the old bed of the brook coincide can only for the pre- 
sent be conjectured, but as the working of the Westville colleries 
proceeds into the improved ground, it cannot be long before the 
actual position of the great break will be determined at one or 
more points along its course. 
If the theory be tenable that it was the ancient brook that 
made the valley, now filled so deeply with drift, it is equally pro- 
bable that the depth of clay, 35 to 70 feet thick, near the railway 
station at Stellarton, indicates that the river channel in pre-gla- 
cial times ran under what is now its left bank, and flowed in a 
course to which its deviations to and fro across the broad interval 
have not since restored it. 
In Acadian geology, page 61, it is stated:—“A very large pro- 
portion of the present feature of the surface is due to the 
denudation in the production of the boulder deposits. The ridges 
of Cumberland, the deep valley of Cornwallis and Annapolis, 
the great gorges crossing the Cobequid Mountains and the 
* Mr Hartley, in the Survey Report for 1869, gives it as 1600 feet only. . 
