236 THE PICTOU COAL FIELD — I'OOLE. 



rocks l»elow the Coal Measures of Mr. Hartley's (.livisi(jn with 

 those of his own much of the rearrangement wliicli now seems 

 called for would have been avoided. 



In the study of the relative position of these barren measures, 

 a scale of hardness in the red argillites perhaps otters a rough 

 and ready test of the age of rocks that otherwise may Icjok 

 identical. (Jn exposure to the atmosphere the harder rocks, for 

 instance, of Oliver's mill dam, present a slaty fracture, those of 

 later orie^in associated with Carboniferous Limestone of McLel- 

 lan's brook crumble into rhomboidal form ; while in the Mill- 

 stone Grit the particles have rounded edges and in the Upper 

 Coal Measures the slickensided fracture of the marls facilitates 

 their conversion into plastic clay. 



Faults. 



The Survey map of 1869 has about the Coal Measures of this 

 district a continuous girdle of faults, presumably of great dis- 

 placement, a displacement which subsequent writers have 

 expressed in feet.* It will be seen later on that grave doubt 

 is expressed whether the field has this structure and modifica- 

 tions are proposed that in parts materially change the outlines. 



A study of the grouping of the faults of the field associated 

 with the zones of varying (juality in the coal seams and specula- 

 tions as to their relative age and influence on the present limits 

 of the basin are not without interest and possible value. 



In the first place it may be noticed that where the circum- 

 scribing rocks are cut down by the passage of water courses 

 there also disturbances pass into or out of the valley. The East 

 river on entering the basin flows in on the strike of measures 

 parallel to the western face of Weaver's mountain, its course 

 northward is over ground known by subterranean workings to 

 be much troubled hy dislocations, but whether the faults of the 

 coal measures wdiich are heavy up to the northern margin also 



Note : — " The colouring of Ked Sandstones " J. W. Dawson, May, 1S4S, Quart. Jour. Geo. Soc. 



» Rutherford, Trans. North of England Instit., .M. E., 1871. The Coal Fields of Nova Scotia 

 Map shews faults of 4000 feet. Gilpin, Trans. Roy. Soc. Can., Sec. IV., 1S87. The Faults and 

 Foldings of the Pictou Coal Field. Puts the displacement between 5000 and 6000 feet and speaks- 

 of the field " as now presented between bounding faults, like layers in a chest." 



