THE PICTOU COAL FIELD — POOLE. 243 



trusion of diorite and coincide with a valley that runs up into 

 the Cambro-silurian hills. 



Potter's Brook fault: — The course of this fault was ruled on 

 the map of 1869 by an unswerving hand across the field, and 

 marked where the bottom of the basin was supposed to be. 

 Careful and repeated examinations of the locality, which gave 

 its name to this fault, shew black shales dipping nearly vertical 

 but with a course IS'' more to the north of east than that pre- 

 viously given to the fault. Either course continued to the west 

 would before very long take it into proved ground where it is 

 not found, and eastward its extension less than a mile would take 

 it into doubtful ground. Sir W. Logan, subsequent to his report, in 

 a letter to Mr. J. B. Moore, remarked that he did not think this 

 fault would be of importance in the Vale area. It thus appears 

 to be only local, marking on the east side of the river the separ- 

 ation of the Albion series of measures from those of Potter's 

 brook section on the north side of the basin. 



McCallocJi's brook fault : — This fault has left its impress on 

 the face of the country to-day, the depression to the west cor- 

 responds with the downthrows while on the eastern side of the 

 Westville section the thrust of the adjoining anticline is crown- 

 ed by a hill. In a short paper on the Surface Geology of this 

 field, previously referred to the opinion is expressed that 

 when the brook, that gives its names to this fault, had its 

 flow renewed after the deposition of the boulder clay, it 

 was raised by that deposit out of its ancient bed and forced 

 by the inclination of the strata and the superimposed deposit 

 to cross to the eastern side of the fault, where it now runs, 

 the ancient channel remaining filled with glacial drift. On 

 descending the brook, the first exposure on the eastern bank is 

 at the crossing of the Pictou Town Branch Railway ; the eastern 

 abutment of the bridge rests on the rocks while the western it 

 on clay. The brook here appear.s to be on the edge of the fault 

 and to continue on down the eastern side until it lea.ves the 

 Coal Measures near Waters' hill and courses onward over older 

 rocks to the Middle river. 



