REVIEWS—GEOLOGICAL SURVEY OF CANADA. 457 
eeeds south-westward for about thirty chains, and in the succeeding 300 yards 
turns gradually south, and ultimately a little to the east of south, before becoming 
concealed. In the other direction, after running some distance, it sinks beneath a 
marsh on the thirty-first lot of the third range, and again makes its appearance 
on the railroad, which it crosses about three-quarters of a mile to the east of the 
Acton Station, meeting and crossing the Black River about 220 yards north of it. 
“The rock underlying the limestone is concealed, but that which immediately 
overlies it at the mine, appears, from partial exposures, to be a lavender-grey 
shale or slate, with a cleavage independent of the bedding. In this slate there 
appears to be irregularly distributed large masses of a harder rock, which is in- 
ternally of a light olive-green, uniformly and finely speckled with darker green 
spots, looking like serpentine, many of which are surrounded with a bluish-grey 
film. The rock, under atmospheric influences, becomes light yellowish-brown on 
the surface, and, in its weathering, strongly resembles some of the serpentines of 
the eastern townships. Some of the masses measure fifty yards in length by 
twenty in breadth; and on the north side of the railroad there is one of twice 
those dimensions, apparently sunk into the top of the limestone. Thin layers of 
the rock occasionally appear to be interstratified evenly among the slates, In thick 
masses, spots of cale spar are sometimes disseminated, giving the rock a cellular 
and somewhat trappean aspect; but there is no evidence that it is intrusive, and 
it occasionally assumes the character of a sandstone, with small quartz pebbles 
running in the direction of the beds. In the speckled part of the rock, very thin 
partitions, of the same colour and hardness as the darker green spots, run in 
several directions. These partitions, on analysis, prove to be a ferruginous chlo- 
rite, and the whole rock may be described as a hydrous silicate of alumina, with 
much iron and magnesia. 
“These slates and harder masses have a thickness of about eighty-five feet. 
They are succeeded by isolated masses of limestone of various sizes and somewhat 
rounded or lenticular forms, some of them attaining magnitudes of thirty yards 
in length by twenty in breadth, and even eighty yards in length by ten in breadth, 
As seen on the surface, they present a succession of protruding lumps, which run 
in a line parallel with the summit of the limestone, turning with it to the south- 
ward at the south-western part of the exposures. These caleareous masses con- 
sist of grey limestone, made up of irregular and apparently broken beds and 
rounded forms, and hold irregular and ragged pieces of chert in more or less 
abundance, with strings and spots of cale spar. The serpentine-like rock some- 
times appears to surround these calcareous masses. ‘ 
“The copper ore appears to occupy a position immediately near the isolated 
masses of limestone, and very little of it to penetrate into the serpentine-like 
rock or the slate. Indications of it oecur on both sides of the calcareous masses, 
and in some places can be traced as if surrounding them; but the chief part ap- 
pears to be beneath them, and intermediate between them and the slates and the 
serpentine-like rock. The vre consists of the pyritous, variegated, and vitreous 
sulphurets of copper, the second species being the most abundant, and the third 
more abundant than the first. The green carbonate also occurs, but if must be 
regarded as a secondary product, formed at the surface and in cracks. The chief 
Vou. V. 21 
