File:The Quarterly journal of the Geological Society of London (13365143413).jpg

126
PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .NoV. 7,
The carbonaceous shales, composed of argillaceous mud charged
with decaying vegetable matter, occur interstratified with thin layers
of coal.
The beds of hmestone are rare, and with the exception of the two-
inch layer. No. 92, very coarse and impure, being charged with car-
bon, bitumen, or siHceous matter. The persistence and uniform
thickness of all the limestone beds, except those numbered 152 and
154, are very remarkable. The two last are separated at low-water
mark by a three-inch layer of shale ; at high-water mark they merge
into one bed, and at eight feet higher up thin out, as represented in
the annexed cut.
Fig. 4.
151 152 153 154
151, 153, 155, Shale. a a. High water.
152, 154, 156, Limestone. b b. Low water.
Only one bed of conglomerate (No. 143) occurs in this section ; it
is composed of small quartz and granite pebbles united in a base of
brown ferruginous clay.
The sandstones, shales and limestones are traversed by two sets of
joints at right angles to the plane of stratification, the course of one
set being S. 80° E., and the other S. 5° W., which consequently di-
vide the beds vertically into blocks of a rectangular form, as nearly
as may be. These joints are of great service in quarrying the sand-
stone beds for building purposes.
There are thirty-one seams of coal in this section, whose aggregate
thickness is 37 feet ; four only are of sufficient thickness to be worked
profitably, viz. —
Nos. ft. in.
78. Indian Cove Seam 4 8
188. Main Coal 6
295. Lloyd's Cove Seam 5
360. Cranberry Head Top Seam ... 3 8
The relative positions of the several seams may be best understood
by referring to the section. The coal is in every instance bituminous ;
the quality of that obtained from the four seams above-named is un-
exceptionable * .
All the coal-seams save one (No. 27), which will shortly be noticed,
and indeed almost every layer of carbonaceous shale, lie upon under-

• About 80,000 tons of coal are raised annually from the Main Seam, of which
  

30,000 tons are consumed in Nova Scotia, the remainder being chiefly shipped to