390 NORTHERN OUTCROP, CUMBERLAND COAL FIELDS—GILPIN. 
Only two of the above seams, namely, the main and new mine, 
are considered workable at the Joggins. We therefore have this 
vast thickness of strata, comprising 4757 feet, yielding in its 
upper half no seams worth oe and in its lower part. only 
four beds meriting the miner’s attention. 
In considering hie ereat mass of sediments, with its alternate 
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 oi Wee ereat 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 measur cal by myself :— 
