TRANSACTIONS OF SECTION C. 617 



waters of the lakes must have been discharged either heneath the ice, as at 

 present happens to the overflow from a chain of ice-dammed lakes on the 

 Malaspina Glacier, or over the top of the ice. 



An important and unexpected result of our brief examination has been the 

 discovery that while ' foreign ' ice was rising along the flanks of the Cheviots to 

 an altitude of 1,000 f t , not only were the spurs free from any native ice-sheet, 

 such as Cheviot or Hedgehope might have been expected to support, but even the 

 lower ends of the intervening valleys were occupied, not by great native glaciers, 

 but )jy lakes. 



The condition.? thus described may have some relation to the fact that while 

 the porphyrites of the Cheviots have furnished the most abundant types of 

 erratics in the drift of the Yorlcsliiro coast, the granite, if present — which is not 

 quite certain — is very rare. 



10. Iirporf o)i tlip, Erratic Blocks of the rirltinh If<Ies. 

 See Reports, p. 283. 



11. Intmm Re.-poH on tlie best Methoch for the Registration of all Type 



Specimens of Fossils in the British Isles. 



12. Report npo7i thf. Present State of our knowledge of the Structxire of 



Crystals. — See Reports, p. 297. 



TUESDAY, SEPTEMBER 17. 



Tlie following Papers were read : — 



1. The Scottish Ores of Cop27er in their Geological Relations. 

 By J. G. GooDCHiLD, F.G.S. 



The ores of copper occurring in Scotland appear, so far as their origin is con- 

 cerned, to be referable to two primary categories. The first of these includes 

 those minerals whose origin is evidently connected with the uprise of thermal 

 waters ; and the second includes those which are due almost entirely to deposition 

 of materials carried down in solution from some rocks at a higher level to others 

 below. The two methods of origin may be likened to the ebb and the flow of the 

 tides. 



To the first category belongs most of the Cbalcopyrites occurring in Scotland, 

 and with that mineral is to be included also Chalcocite and Bornite. These 

 mostly occur iu conuection with mineral veins. A small percentage of other 

 compounds of Copper with Sulphur appears to have originated in connection with 

 certain eruptive rock of sub-basic composition. When these latter have been 

 affected by dynamic metamorphism the process seems to have favoured the local 

 concentration of the mineral which was formerlj' diffused. Hence several 

 Epidiorites contain Cbalcopyrites, apparently as an original constituent (if we 

 regard their schistosity as original to that type of rock). 



To the second category, that of the ebb-products or minerals of secondary 

 origin, belong all the remainder. 



Taking these in the order, and with the numbers, adopted by Dana, we have 

 first, (15) Native Copper. There cannot be much doubt that all the Scottish 

 specimens of this are of secondary origin. The earlier stage seems to have been 

 that of solution, along with those of the constituents of a sub-basic eruptive roCk 

 through which, probably, the copper ore was originally diffused in very minute 

 quantities. The decomposition of the rock by surface agencies has again converted 



IT u 2 



