582 THE UPPER SILURIAN. 



Before leaving these rocks, I must state that their boundaries, as 

 marked on the map, are often very rude approximations to the truth. 

 It is impossible in the present state of our knowledge to distinguish 

 accurately between these older rocks and the Carboniferous beds which 

 have in many parts of their borders been metamorphosed with them, 

 or to indicate accurately the position and limits of the irregular masses 

 and dikes of igneous rocks. An immense amount of labour will be 

 required before these disturbed and altered rocks can be accurately 

 mapped, or their intricacies fully unravelled. 



Useful Minerals of the Upper Silurian in Nova Scotia. 



Iron, in veins traversing the altered rocks, abounds in this district ; 

 and it also occurs in thick beds coeval with the neighbouring slates, 

 and filled, like them, with fossil-shells. I shall first notice those de- 

 posits which are veins properly so called. These, though occurring 

 in many places, have been worked only along the southern slope of 

 the Cobequid Hills in Londonderry, in the vicinity of the Great Village 

 and Folly Rivers. This deposit appears to have been noticed as early 

 as the time when the land on which it occurs was granted by the 

 Crown ; and it received some attention from Mr Duncan and other 

 gentlemen in Truro nearly twenty years ago. No steps were, however, 

 taken toward its scientific exploration until 1845. In the summer of 

 that year I received a specimen of the ore for examination, and in 

 October of the same year I visited and reported on the deposit. In 

 the same autumn it was examined by Dr Gesner. In 1846 I again 

 visited it, and reported on it to C. D. Archibald, Esq., of London, 

 and other gentlemen associated with him ; and in the summer of 1849 

 I had the pleasure of again going over the ground and examining the 

 vein at some new points, in company with J. L. Hayes, Esq., of 

 Portsmouth, U. S. Since 1849 the extent and economical capabilities 

 of the deposit have been discussed by several writers, both in this 

 province and in Great Britain ; and it has been opened, and smelting 

 furnaces erected by an association of capitalists. 



I shall begin by describing the vein as it occurs on the west branch 

 of the Great Village River, at the site chosen by C. D. Archibald, 

 Esq., for the furnace and buildings of the " Acadia Mine," and as seen 

 in 1849. In the western bank of this stream, at the junction of the 

 Carboniferous and Metamorphic series, a thick series of gray and brown 

 sandstones and shales of the former system, dipping to the south at 

 angles of 65° and 70°, meet black and olive slates, having a nearly 

 Vertical position, and with a strike N. 55° E. The dip of these slates, 

 where apparent, is to the southward, and the strike of the slaty 



