42 Reports and Proceedings — 



•were deposited in the valleys. As the land rose again, ice-clad hills 

 returned, and new though perhaps less extensive glaciers were 

 formed, and fresh crops of boulders were deposited in the shallowing 

 seas of the Saxicava period. Snow still exists throughout the sum- 

 mer in the higher ravines of the White Mountains, and on the hills 

 of Labrador, and a subsidence of a few hundred feet in the valley 

 of the St. Lawrence and the country to the southward, would suffice 

 to restore them to the condition of snow-clad hills giving off" icebergs 

 from their bases, so near are we yet to the Glacial Period ; and so 

 little did it really differ from that condition of the continent which 

 still exists." 



IZth December, 1872. Gr. A. L. 



i2,E^oi2,Ts j^isTJD :PI^ocs:E5DI^^a-s. 



Geological Society of London. — I. — Nov. 20, 1872. — Prof. P. Martin Duncan, 

 F.R.S.,V.P., in the Chair. — The following communications were read: — 1. "On the 

 Geology of Thunder-Bay and Shabendowan Mining Districts on the North Shore 

 of Lake Superior." By H. Alleyne Nicholson, M.D., F.G.S., etc. 



The author described the general characters of Thunder Bay, which is almost 

 landlocked on the south-east by the bold promontory of Thunder Cape and a series 

 of islands which form a continuation of it. The rocks immediately surrounding 

 Thunder Bay belong to the "Lower and Upper Copper-bearing series " of Canadian 

 geologists. The latter, consisting of sandstones, shales, limestones, marls, and 

 conglomerates, chieiiy of a red or reddish colour, with interstratified traps, is regarded 

 by the author as probably of Lower Silurian age, in accordance with the opinion of 

 Sir Wm. Logan. The "Lower Copper-bearing series" is also very varied in 

 character ; it is traversed by trap-dykes, and contains several well-marked inter- 

 stratified traps. It is penetrated by two sets of mineral veins, containing great 

 abundance of silver. The majority of these run along the strike of the beds in a 

 general E.N.E. and W.S.W. direction; the remainder are transverse, running nearly 

 N. and S. Of the latter the most important is the " Silver-islet vein," which is three 

 or four feet in width, and consists of quartz with native silver and galena ; picked 

 specimens of the stuff have assayed from £1000 to £2000 per ton. This vein has 

 been worked for about two years, and has proved remarkably productive. Of the 

 former series the most important is the " Shuniah vein," which runs along at a 

 distance of one and a half to two miles from the north shore of Thunder Bay, the 

 mines in which, although quite in their infancy, promise excellent results. Its width 

 is twenty-two feet, and the vein-stuff consists mainly of calc-spar. The silver is 

 present in the native form, and as sulphide. The vein traverses hard black shales, 

 but does not run exactly along the strike of the beds ; it may be traced for several 

 miles towards the east. 



The country between Thunder Bay and Lake Shabendowan, along the " Dawson 

 Road," is of an undulating character, and the surface of its fundamental rocks every- 

 where exhibits unmistakable evidences of glaciation, the general direction of the 

 striae being N. and S., but with the occasional occurrence of a minor set of grooves 

 running nearly E. and "W. The greater part of the country is thickly covered with 

 drift, composed of rocks which appear to have travelled from north to south. 



The rocks passed over between Thunder Bay and Lake Shabendowan are described 

 by the author as, 1, the shales and traps of the "Lower Copper-bearing series"; 

 2, a range of syenitic and gneissic rocks, probably of Lam-entian age; 3, a great 

 series of rocks belonging to the Huronian group, consisting of greenish or grey slates, 

 with bands of gneiss and trap-dykes, and bedded green trap^ with great masses of 

 greenish, grey, or drab-coloured slates, the whole presenting a close resemblance to 

 the green slates and porphyries of the English Lake-district. The slates, in the 

 author's opinion, are bedded felspathic ashes. 



The author described the general characters of Lake Shabendowan, and stated that 

 from the foot of the lake for about fifteen miles westward there is a succession of 

 trappean rocks, beyond which, to the head of the lake, distant thirteen miles, the 



