THE CARBONIFEROUS OF CAPE BRETON—GILPIN. 297 
much of it must be considered contemporaneous with the lime- 
stone formation. In the Sydney district, near the Coxheath Hills, 
it has a thickness of 2,525 feet, which rapidly diminishes as its 
strike is followed te the North and the South. 
This formation in the Sydney or Eastern district presents 
itself generally as a friable reddi-h conglomerate, the pebbles 
varying in size up to a diameter of three feet. The masses are 
frequently of little coherence, in some cases the matrix is cale- 
spar, hematite, or quartz. The conglomerates, the distinguishing 
feature of the formation, alternate with masses and beds of red- 
dish, coarse and fine grained, friable sandstones, and with beds of 
red and green marl and an occasional bed of limestone. Usually 
the upper beds are finer than those near the base of the formation, 
and the line between it and the succeeding horizon may be said 
to be drawn at the first plainly marked caleareous deposit, which 
is not unfrequently a eoarse arenaceous limestone obscurely 
fossiliferous. 
Passing to the westward we meet the Carboniferous of St. 
Peter's Bay and the River Inhabitants. The marine iimestones 
and some beds of the lower horizons border St. Peter’s Inlet and 
Bay and the northern shores of Isle Madame, and passing to the 
north under the higher measures skirt the Sporting Mountains, 
and passing round the head of West Bay fill the valley of the 
River Inhabitants and are exposed on the shore of the Strait of 
Canso at Plaster Cove. These strata show at several points sec- 
tions more closely resembling the typical lower coal measures of 
Nova Scotia than any met in the Eastern district. The colour- 
ing of the geological maps of the Canadian Survey does not 
‘separate these two subdivisions. They extend northward until 
they reach the River Denny’s Basin, and stretch to the Grand 
Narrows and the Little Bras d’Or. 
The officers of the Geological Survey have grouped the Car- 
boniferous measures overlying these strata, in the district we 
are now considering, under the term “Middle Carboniferous,” 
including millstone grit, productive measures, and some beds 
_referred with doubt to the upper coal formation, as the dividing 
lines are obscure, and the structure not yet fully worked out. 
