Macjarlane on the Acton Copper Mine, 463 



rent, broken, bent and twisted in the most violent manner, is evi- 

 dent from the various phenomena presented in every part of the 

 mine. Whether this upheaval was caused by the greenstones 

 being thrown up from beneath, seems to be uncertain, but it is 

 probably not unreasonable to suppose that this protrusion of the 

 greenstone occurred simultaneously with the upheaval of the 

 strata ; and that both may have been caused by certain more gen- 

 eral and wide spread movements of the earth's crust. Whatever 

 may have caused the upheaval, it seems sufficiently evident that 

 the upheaval caused the rending of the limestone, the formation of 

 the fissures and crevices, in which the copper ore was subsequently 

 deposited, and the partial filling up of these by detached fragments 

 of limestone of all possible dimensions. With regard to the fill- 

 ing up of the fissures by the copper ores, we may conceive three 

 different modes in which this may have been eff'ected : 1. The 

 ores may have been injected into these fissures in a fused state* 

 2. They may have been removed from the impregnated side 

 rock by certain solvents, and re-deposited in the fissures. 3. They 

 may have been brought up from beneath by springs. With re- 

 gard to the first of these theories, it must be remarked that the 

 general appearance of the veins, coupled with the presence of green- 

 stone in the neighborhood, would seem to be in its favor. But 

 when it is considered that the ore is intimately associated with 

 quartz, or rather with chert, this view of the origin of the ore does 

 not appear admissible. It is difficult to conceive of a fused material 

 so homogeneous as the substance which forms the matrix of the brec- 

 cia, consisting exclusively of metallic sulphurets and silica. And 

 even although it were possible to imagine a fused mass of this 

 composition, the degree of heat required for its fusion would have 

 been such as to exert an action on the adjoining limestone, simi- 

 lar to that produced by certain igneous rocks, viz., a conversion of 

 the greyish colored limestone into white crystalline marble. 

 With regard to the second theory, the presence of sillica does not 

 present any difficulty, because it is a well-known fact that that 

 substance is deposited in large quantities from hot springs. It is 

 not unreasonable to suppose that the water percolating through 

 the rocks possessed a high temperature, because it is not unlikely 

 that a higher temperature than the present prevailed after the 

 Lower Silurian strata had been deposited. With regard to the 

 manner in which the copper may have been dissolved, and held 



