354 The Acton Copper Mines* 



little to tlie 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 ap- 

 pearance on the rail road, which it crosses about three quarters 

 ofa mile to the east of the Acton station, meeting and crossing" 

 the Black River about 220 yards north of it. 



" The rock underlying the hmestone 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 appear to be irregularly dis- 

 tributed large masses of a harder rock, which is internally of a 

 light olive-green, uniformly and finally speckled with darker 

 green spots looking like serpentine, many of which are surrounded 

 with a bluish-grey fiilm. The rock under atmospheric influences 

 becomes light yellowish-brown on the surface, and in its weather- 

 ing strongly resembles some of the serpentines of the Eastern Town- 

 ships. Some of the masses measure fifty yards in length by 

 twenty in breadth, on the north side of the rail road there is one 

 of twice those dimensions, apparently sunk into the top of the 

 limestone. Thin layers of the rock occasionally appear to be inter- 

 stratified evenly among the slates. In thick masses spots of calc 

 spar are sometimes disseminated, giving the rock a cellular and 

 somewhat trappean aspect, but there is no evidence that it is in- 

 trusive 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 fer- 

 ruginous chlorite, 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 lime- 

 stone of various sizes and somewhat rounded or lenticular forms, 

 some of them attaining magnitudes of thirty yards in length by 

 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 southward at the south-west- 

 ern part of the exposures. These calcareous masses consist of 

 grey limestone made up of irregular and apparently broken beds 

 and rounded forms, and bold irregular ragged pieces of chert in 



