2G2 ANNUAL OF SCIENTIFIC DISCOVEUY. 



" It may, however, be objected, tliat, if this tlioory of distillation 

 be true, we ought somewhere to liiul tlie re.si(Uuuii, or clebilumin- 

 ized shales, etc., remaining alter the oil had been extracted. Such 

 discovery could not justly be expected iu surface rocks, because, 

 according to the theory, {he heat agency woultl at best be small, 

 and could be scarcely ielt near the surface. The question, then, 

 •would be reduced to this, viz.. Do the borings in deep wells ever 

 show that the deep iMtuminous straUi have lost any of their origi- 

 nal and normal (piantity of l)itumen?" 



After presenting some facts bearing upon this point, he con- 

 cludes as follows: "Such facts are not conclusive as to any 

 l)ositi\e loss of bitumen, but they are not without signilicance. 

 Should 1 liud many similar cases where strata, which are iiighly 

 bituminous at their outcrop, are found to contain little bitumen at 

 grt':it depths, and, at the same time, the rocks above these 

 buried strata containing in their fissures much oil, I think the in- 

 ference, that the oil was derived from the bituminous shales, not 

 luiwarrauted." 



ACTION OF ICE IN FORMING LAKE BASINS. 



■Mr. Thomas Belt has published an essay, in which he main- 

 tains the action of glaciers in forming lake-basins. Supposing, 

 he says, the existence of a depression in the pathway of a glacier 

 which has reached such a depth that the ice simply fills it, Avhat 

 would happen ? At the bottom and sides of the hollow, tiie ice 

 would be slowly melted by the earth's heat, increasing with the 

 dejHh of the basin. As the ice at the lower end of the basin 

 melted, the whole mass would be pushed along by the thrust of 

 the moving glacier above it. Into the crevice at the upi^er end 

 would pour the water, coming down the bottom of the glacier, 

 from above the basin, which would j)ass underneath and be 

 forced out at the lower end, carrying with it the mud produced 

 by the crushing down of the ice as it melted at the bottom, and 

 by the grinding along its floor as it melted at the lower end of 

 the basin. The water coming from above would assist in melt- 

 ing the ice, especially in summer ; but its most important eliect 

 would be the scouring out of the bottom of the. basin, so that an 

 ever-clean face of rock would be presented to the huge natural 

 tool operating upon it. Such an action would, in some measure, 

 resemble that of a hollow drill, which has been prepared for 

 boring holes iu rock, throuf^h which a current of water is forced 

 to carry off the ground stone. Mr. Belt accounts for the differ- 

 ence in depth of the lake-basins of Switzerland and Nova Scotia 

 by stating that, in one case the ice-chisel operated on hard gran- 

 ites, and in the other, on soft, easily-worn materials. — Transac- 

 tions of the Nova Scotia Institute of Natural Science,Vol. II., No. 3. 



ORIGIN OF THE SALTS WHICH COMPOSE THE EARTH. 



Mr. T. Sterry Hunt gives the following theory of the origin of 

 salts, metallic veins, and other deposits, starting with the idea 



