364 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [March 13, 



I first heard of these deposits in 1845, when exploring the country 

 in the vicinity of the St. Clary's River, but at that time I had not 

 leisure to visit them . I examined them with more care in the spring 

 and summer of 1848 ; and I beheve there is a prospect that mining 

 operations will soon be commenced on the vein near Poison's Lake, 

 which promises to be a valuable deposit of copper pyiites, and is I 

 beheve the first workable copper vein discovered in the metamorphic 

 districts of Nova Scotia. 



x\t South River Lake, two miles eastward of Poison's Lake, specu- 

 lar iron ore is said to occur in large quantity. The metamorphic 

 country eastward of this place, and that hiug immediately westward 

 of the Lochaber Lake, have been little explored. In the east branch 

 of the St. Mary's River, about seven miles westward of Lochaber 

 Lake, though the rock formations are similar to those eastward of 

 that lake, I saw no metalliferous veins. 



The mineral deposits of the metamorphic districts, to which this 

 paper refers, have only recently attracted pubhc attention ; and it 

 may be anticipated that every year will extend our knowledge of these 

 deposits. The details of the rock formations themselves still remain 

 to be worked out ; and in the present state of these districts this 

 must require much time and labour. It is also e^ddent that the 

 transition from highly metamorphic to unaltered Silurian and carbo- 

 niferous beds, on the confines of one of these metamorphic groups, 

 must oppose great difficulties to the accurate mapping-out of the 

 hmits of those systems in this part of Nova Scotia. In the mean 

 time, the facts contained m this paper may aid in the formation 

 of general views of the geology of this province ; and may afford 

 some new terms of comparison with the metamorphic rocks and mi- 

 neral veins of other countries. 



2. On the Structure of the Crystalline Rocks of the Andes, 

 and their Cleavage-Planes. By Evan Hopkins, F.G.S. 



It is a well-known fact to those who have traversed large areas of 

 uncovered crystalhne rocks, that they present a structure more or less 

 vertical. In North America, Scotland, and Sweden the diversified 

 edges of the crystalline series may be traced for many miles, pre- 

 senting a north-easterly structural bearing. TVTiere argillaceous sedi- 

 mentary beds have been deposited on crystalline rocks, ha\dng the 

 above vertical structure strongly developed, I have frequently observ-ed 

 the latter, by a slow chemical action, in the course of time obliterate 

 the seams of deposition in the former, and cleave the beds in confor- 

 mity to the angular position of the primary structure and the dis- 

 position of the crystals in the crystalline base. 



These cleavage-planes pass through mountains of undulated beds, 

 and preserve throughout the various contorted seams, the geometrical 

 parallelism of the structure of the parent rock below ; thus plainly 

 showing the effect of a polar crystallizing force, acting gradually and 

 insensibly on the whole mass in one direction to an indefinite extent. 



