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SECTION IV. 1886. [itso] Trans. Roy. Soc. CANADA. 
XII.—WNotes on the Limestones of East River, Pictou, NS. 
By Epwin Gizrin, Jun., A.M., F.G:S. 
(Read May 27, 1886.) 
The following analyses of limestones, from the Lower Carboniferous Marine Limestone 
series of Pictou County were made some years ago by the writer, when engaged in an 
investigation into the subject of fluxes for the extensive deposits of iron ore which 
characterize this district, and they may be appropriately prefaced by a few remarks on 
the extent and distribution of the Lower Carboniferous measures of East River. 
The general arrangement of the subdivisions of the Carboniferous system in this 
county can be readily recognized, and is given in sufficient detail in Sir W. Dawson’s 
“ Acadian Geology.” It may be remarked that, in the district more particularly referred to 
in these notes, viz., that extending from Glengarry, on the Intercolonial Railway, to 
McLellan’s Mountain, the Lower Coal formation does not appear, and may be represented 
on the eastern edge of the district by the conglomerate beds of Irish Mountain and 
McLellan’s Brook. 
On Big Brook, a tributary of West Branch, about four miles above Hopewell, are met 
limestones and gypsum with red shale and flaggy sandstones, resting on Siluro-Cambrian 
measures, and dipping to the north. These limestones are exposed on the West Branch 
and can be traced south of Grant’s Lake to the valley of East River. They are associated 
with red shales, and red and gray sandstones, and the measures are broken through by 
several masses of the dioritic trap, probably contemporaneous. Exposures of gypsum are 
not met until near the mouth of Archibald’s Brook. Here a compact, blue limestone, about 
thirty feet thick, is overlaid by marl, and by an immense mass of gypsum, about 100 feet 
in thickness. 
It is impure in quality, and contains layers of marl and siliceous matter. In the 
upper part, are layers of granular and fibrous, red gipsum. Above this come beds of hard, 
red, shale, having a general dip to the west. The course of the gypsum, as marked by 
funnel-shaped pits, is southerly or parallel to that of the river. Its final exposure in this 
direction is distant about three miles, at the Black Rock, where a small outcrop is visible 
on the east bank of the river, on the farm of Mr. J. McDonald. At this point, it is associated 
with a pyritous, greenish, compact marble, and a compact, blue limestone, carrying limonite, 
and the section rests on a great mass of an indurated breccia, connected with the Cambro- 
Silurian measures of the opposite bank of the river. 
Underlying the strike of the gypsum, on the west side of the river, are frequent 
exposures of hard, shaly, red sandstone, of soft marl, and of red and green argillaceous 
shales, interrupted at several points by dykes of black and dark-green dioritie trap. These 
measures rest on the Cambro-Silurian slates, carrying specular and limonite iron ores, and 
