32 CARBONIFERVUUS OF CAPE BRETON—GILPIN. 
may be found useful at an early date. It is of interest to glance 
at their former seaward extensions. Part of Port Hood Islands 
and Margaree Island are composed of Middle Carboniferous, and 
they are the relics of a vast coal field extending for miles under 
the Gulf of St. Lawrence, and gradually worn away by its tides 
and currents. Even in historic times we have seen marks of the 
progress of destruction in the sweeping away of Port Hood Bar, 
and undermined cliffs at numerous localities. 
In the district we are considering, Mr. Fletcher has divided 
the remaining Carboniferous strata into two groups, on which 
be remarks : 
“Conglomerate—At or below the base of the lower Carboni- 
ferous, in several places occur strata, greatly altered by the 
intrusion of igneous rocks. They frequently resemble the supposed 
Devonian of the Isle of Madame, but are more probably for the 
most part Carboniferous, and underlie the Marine Limestone.” 
The more important and most highly altered rocks of this 
series, occur at Mabou, Strathlorne, South West and North 
East Margaree and Cheticamp.. They comprise, argillaceous and 
arenaceous shales, and sandstones and conglomerates with diorites 
and tuffs. Similar but less highly altered grits, sandstones and 
conglomerates occur in the ridge between the Baddeck River 
and St. Patrick’s Channel at Middle River, Mabou, Lake Ainslie, 
Syke Glen, ete. 
One band of these measures, begins at Low Point, on the 
Strait of Canso, and runs to Lake Ainslie in a band about five 
miles wide. A branch of it running down the West River of 
Whyhogomah forms the Salt Mountain, and gradually widening 
occupies great part of the district between Lake Ainslie and the 
mouth of Middle River, and following the west bank of the 
Middle River terminates near Loch Ban. 
Other isolated patches are met on both sides of Loch Ban, 
and between the branches of the Margaree. Another irregular 
band, beginning at the forks of the Margaree, on the east side of 
the river, follows it down to within a mile of the shore, to which 
it pursues a roughly parallel course until it ends on the Cheti- 
camp River, about five miles from its mouth, and has for its 
