390 NORTHERN OUTCROP, CUMBERLAND COAL FIELDS — GILPIN. 



Only two of the above seams, namely, the main and new mine, 



are considered workable at the Joo-gins. We therefore have this 



vast thickness of strata, comprising 4757 feet, yielding in its 



upper half no seams worth mentioning, and in its lower part only 



four beds meriting the miner's attention.. 



In considering this great mass of sediments, with its alternat- 

 es o > 



ing layers of coal, clay, sandstones and limestones, it must be 

 borne in mind that the various changes chronicled at the Joggins 

 did not necessarily extend over the whole of the Cumberland 

 coal field. But, as Dr. Dawson remarks, had we visited the dis- 

 trict during the coal period, we might, by changing our position 

 a few miles, have passed from a sandy shore to a peaty swamp, 

 or the margin of a lagoon. The evidence of similar districts at 

 the present day, and the sections of their coal fields, show that, 

 although these changes would be visible in passing over the 

 ground, still the horizons of deposition, whether of vegetable mat- 

 ter or of sandstone, etc., vary very little, and that the persistence 

 and regularity of the coal beds is greater than that of the associ- 

 ated measures. We thus find in Cape Breton coal seams preserv- 

 ing over considerable areas a uniform size and relative position 

 while marked variations are observed in the thickness of the 

 containing beds. Had we visited the district we are considering 

 at a period coinciding with the formation of one of the coaly 

 beds, we would have seen on all sides vast swampy plains covered 

 with dense forests of strange shapes and unknown hues ; calam- 

 ite brakes and peaty bogs, traversed by sluggish streams and 

 shallow lagoons, impeded and changed in their course by the 

 luxuriant and encroaching vegetation. Again, a visit at the time 

 of deposition of some of the great beds of barren sandstones 

 would have shown us a wide and shallow sea filled with sandbars 

 and low islands, on which grew straggling calamites, fighting for 

 an existence amid the shifting sands. 



We may now briefly pass in review the sections of the seams 

 presented at the various mines which have been opened on the 

 eastern extension of these strata. 



Near the shore the Joggins main seam presents the following 

 section recently measured by myself : — 



