384 THE DEVONIAN OF CAPE BRETON—GILPIN. 
refer some of the strata to the Silurian, on the analogy of other 
parts of Nova Scotia. To clear up these questions, which are 
more easily asked than answered, a much more detailed survey 
and study would be required. | 
Good examples of the unconformability between the Carbon- 
iferous and Devonian are met here, where the former, little 
altered, come into contact with and hold pebbles of the meta- 
morphic rocks. Between Rocky Bay and Lennox Passage there 
seems to be a vertical thickness of 10,000 feet of strata. 
1n general character the rocks of this district resemble those 
of the same formation, as exposed about Loch Lomond and Grand 
River. Mr. Fletcher appears, upon more mature reflection, to 
question if the limestones of St. Peter’s may not be at the base 
of the Carboniferous, and that their alteration by the igneous 
rocks of the locality mark the Carboniferous date of the meta- 
morphic action. I do not myself recognize much resemblance 
between any of the St. Peter’s diorites, etc., and undoubted Car- 
boniferous dykes which I have seen elsewhere. However this 
may be viewed, the limestone, whether placed at the top of one 
formation or at the bottom of the succeeding one, may be looked 
upon as marking a period of change, with differences in level, 
and the consequent change in nature of sediments. 
Over large parts of Arichat Island are beds of quartzite and 
sandstone, with reddish and purplish conglomerates, giving a 
rocky, rough surface, barren, and intersected by swamps. Petit 
de Gras Island is largely made up of conglomerates. At Rocky Bay 
coherent grit and fine conglomerate, with their irregular veins of 
quartz, are succeeded by purple, greenish, and gray grits, Indian 
red, gray, flaggy, arinaceous, cleft and jointed rocks, sometimes 
friable, and pearly with quartz in films, blotches and veins con- 
taining much chlorite. The different varieties seem to be con: 
fusedly mixed, the sandstone passing on one hand into fine granu- 
lar quartzite,and on the other into compact sandstone, often almost 
replaced in the bedding and across it by veins of quartz and 
ealespar. The abundance of calespar in all the rocks on the 
island is noteworthy, but I am not aware that it carries any 
notable amounts of metallic sulphides, etc. Fossil plants are 
