THE DEVONIAN OF CAPE BRETON—GILPIN. 385: 
frequently found. The general trend of the measures appears to 
run lengthwise through the island and to connect naturally with 
the St. Peter’s and the Guysboro’ districts. The exposures of 
diorite, etc., are not as prominent a feature here as in the former 
district, but examples can be noticed where the dykes cut the 
beds and pass laterally between them, with comparatively local 
amounts of metamorphism. 
Passing to the third area of Devonian rocks, we find them 
exposed beneath the limestone of Plaster Cove. They consist of 
greenish quartz, felspathic sandstones, associated with dark 
greenish, veined, very coherent shale and sandstone, conglome- 
rate, and black shales. On the Victoria Road, a mile and a half 
from Hastings, are whitish coherent grit, and conglomerate, with 
many veins of quartz. Some of the exposures of grit and shale 
are soft and crumbly, while others are hard and flinty. Dykes 
of diorites are met, but as a rule their effect on the strata is very 
local, and the metamorphism has been regional. Frequent junc- 
tions with the precambrian syenites and felsites are observed. 
In general, these strata resemble those of Arichat and St. Peters, 
and the fossils they present are similar. 
The minerals of the Devonian of Cape Breton are limited in 
number. I am not aware of any quarries having been opened in 
them for building purposes, although the surface blocks are locally 
used for foundations, bridges, etc. Limestone is met at several 
places. That of St. Peter’s inlet has been quarried and burned 
to a small extent, and was utilized during the construction of the 
canal. The bed of limestone between Pirate’s Cove and Mulgrave 
was quarried on quite an extensive scale some years ago, and ex- 
ported chiefly to Prince Edward Island. Behind the chapel at 
Arichat there is a quarry in a dark grey compact limestone, veined 
with calespar. The limestone at Pirate’s Cove is said to be some- 
what hydraulic, and contains fluorspar. 
The occurrence of fluorspar in these measures leads to a hope 
that this mineral, which is of considerable value, may be found 
in amounts of economic importance. In 1887, 3000 tons were 
mined in the United States and valued at the mines at $20.000. 
About two-thirds was used in iron, brass and steel works; the 
mn 
