Reports & Proceedings — Edinburgh Geological Society. 239 



which are black in colour, but yellowish-green in thin sections, and 

 of two tvpes, simple and twinned, and have the axial constants 

 a: 5 : c = 0-5844 : 1 : 1-0932, /3 = 105° 48', and refractive indices 

 1-708, 1-713, 1*728. Sections parallel to the plane of symmetry 

 show the hour-glass structure characteristic of titaniferous augite. — 

 Dr. G. T. Prior: On a Sulpharsenite of Lead from the Binnenthal. 

 Analysis of the crystals, on which the prism zone alone was 

 developed, showed that the composition corresponded to the formula 

 3 Pb S . 2 As^ S3, which is that attributed to rathite ; crystallo- 

 graphically, however, the crystals seem nearer to dufrenoysite. — 

 Dr. G. T. Prior: On Phacolite and Gmelinite from County Antrim. 

 In both instances analysis of these minerals, which are varieties of 

 the same species, differing in habit of crystal, showed an excess 

 of hydrated silica over tbe composition represented by the formula 

 (Ca, Naa) Alg Sii O12 . 6 Hg 0. 



III. — Edinburgh Geological Society. 

 March 25, 1914.— Dr. John S. Flett, F.Pt.S., President, in the Chair. 



1. " On a Visit to the Klondvke Goldfields." 2. " The Glaciation 

 of Alaska." (Illustrated.) By H. M. Cadell, B.Sc, F.K.S.E. 



The object of the papers was to give an account of the Klondyke 

 goldfields and the glaciers of Alaska visited by the author last autumn. 



During last century there had been a great shrinkage in the glaciers, 

 but some of them had begun to advance .since the great earthquake in 

 September, 1899. The traces of the earthquake were still very 

 distinct. Parts of the coast were upraised 40 feet in places, and 

 gaping fault-fissures were plainly seen. On the way from the water- 

 shed towards Dawson City and Klondvke the signs of glaciation 

 became less and less, and in the goldfields it was clear there had 

 never been any glacial action at all, though it lay so far north. 



The old plain gravels in the Klondyke valley and other places had 

 never been disturbed since Pliocene times, except by changes in the 

 river system that had occurred in consequence of alterations of the 

 level of the land. This absence of ice was due to the dryness of 

 climate in the Glacial period in that region, and not to a warmer 

 climate. The gold-bearing gravels were frozen solid to a depth of 

 100 feet, and contained bones and tusks of mammoths and other 

 animals. There were two sets of placer gravels, one in the bottom, 

 and another higher up on the side of a few of the valleys. The older 

 gravels had no animal remains in them, and were nearly white in 

 colour. The level had been upheaved 700 feet, and the rivers had 

 cut out deeper glens before the newer gravels were produced, and the 

 gold was washed out and deposited in the beds of the creeks, where 

 it had lately been, and still was being worked, but on a smaller scale 

 than in 1900. 



The total yield of the goldfield was about £30,000,000, and in 1913 

 there was still a production of £1,000,000 by dredging and hydraulic 

 sluicing companies with a large capital. Klondyke was no longer 

 a poor man's goldfield, and there was still a good deal of gravel that 

 could be profitably worked by means of extensive plant. 



