290 THE CARBONIFEROUS OF CAPE BRETON—GILPIN. 
basin of the Gulf of St. Lawrence. Its former immense extent 
is marked by the Bonaventure series of Gaspe and the Carbon- 
iferous Limestone, etc., of the Magdalen Islands, north of Prince 
Edward Island, and of Pictou and Antigonish Counties. Begin- 
ning at Cheticamp, this division extends along the North-Western 
shore of the Island, gradually widening, until at Lake Ainslie it 
is about fifteen miles wide; it then narrows, until at the Northern 
entrance to the Strait of Canso it appears connected with the 
Carboniferous of Nova Scotia proper. 
Another district, beginning at the southern end of the Strait 
of Canso, spreads out in two arms, one running between Lennox 
Passage and the Sporting Mountains, pas<es to the North of St. 
Peter’s and terminates at Cape George; the other, continuing 
up the River Inhabitants, crosses into the water-shed of the 
River Dennys, and passing along both sides of St. Patrick’s 
Channel, finally terminates at St. Anne’s Harbour. Along its 
northern edge, from Whyhogomah to St. Anne’s, it projects in 
long narrow tongues among the crystalline rocks. 
This district connects through Boularderie Island with the 
third or eastern district, which extends from Cape Dauphin 
through Sydney to the Mira River. Connecting with this district 
is a long irregular band of the same measures, extending along 
the Salmon and Grand Rivers. 
In addition to these principal divisions there are numerous 
small isolated patches of carboniferous measures along the south- 
eastern shore of the Island, which, taken in eonnection with the 
exposures of Guysboro, St. Margaret’s Bay and Chester, in Nova 
Scotia proper, would show that once the Atlantic front of the 
Province was covered by the lower measures at least of the 
Carboniferous system. The pre-cambrian rocks of the Bras d’Or 
Lake are generally flanked by narrow fringes of the Marine 
Limestone and Lower Coal Measures. 
At St. Lawrence Bay, in the extreme North of the Island, is 
a considerable area of Lower Carboniferous Measures, as is also 
the case at Aspy and Ingonish Bays. Between these points the 
pre-cambrian felsites and syenites either come boldly to the sea or 
have a narrow fringe of these measures. 
The general arrangement of the Carboniferous of the Island 
