Superficial Geology of North-ioestern Canada. 77 



as islands above the sheet of ice. Some of the surface erratics of 

 gneissose rock have doubtless been, derived from the Till, whilst 

 others are connected vs'ith moraine deposits, and others, again, appear 

 to have been dropped from bergs floating in seas along the ice- 

 front. The Till is sometimes divisible into a lower massive and 

 upper rather stratified deposit, separated occasionally by 



3. Interglaclal Deposits of stratified material, with seams of im- 

 pure lignite, and shells of Pisidium, Lhnncea, Phmorbis, &c. 



4. Moraines, which are intimately associated with the Boulder- 

 clay, and represent terminal moraines of ancient glaciers which 

 originated upon or crossed the Archaean belt. One of these is the 

 well-known Missourie Coteau. 



After pointing out the derivation of quartzite pebbles in the 

 drifts of the eastern region from Miocene conglomerates, and not 

 directly from the Eocky Mountains, the author described 



o 



5. The Karnes or Asar generally occurring at the bottoms of 

 wide valleys, and which resemble in structure those of Scandinavia. 



6. Stratified Deposits and Beach-ridges which have been formed 

 at the bottoms and along the margins of freshwater-lakes lying 

 along the foot of the ice-sheet. The principal of these occupied the 

 valley of the Red Eiver, and has been called Lake Agassiz ; it had a 

 length of 600 miles and a width of 170 miles. The author described 

 in detail the gravel terraces formed around this lake, and showed 

 that a slow elevation had taken place towards the north and east 

 since their formation. He favoured the view that the waters of 

 the lake were dammed by the ice towards the north. An account 

 was given of some quartzite flakes, apparently chipped by human 

 agency, in one of the terraces of this lake. On the recession of the 

 ice the southern drainage-channel was abandoned, and a northerly 

 one opened out. 



7. Old Drainage-channels. — Throughout the whole region old 

 drainage-channels appear to have been occupied by southerly run- 

 ning rivers (where the present drainage is northerly), and are con- 

 sidered to have carried away the waters draining from the foot of 

 the ice. Some of these valleys have been blocked by moraines in 

 the Duck Mountains, the result of local glaciers. 



Nov. 21.— W. T. Blanford, LL.D., F.E.S., President, in the Chair. 



"W. "\\'hittaker, Esq., B.A., F.E.S., F.G.S., who exhibited a series of 

 specimens from the deep boring at Streatham, made some remarks 

 upon the results obtained, of which the following is an abstract: — 



After passing through 10 feet of gravel &c., 153 of London Clay, 

 88| of Lower London Tertiaries, 623 of Chalk (the least thickness 

 in any of the deep borings in and near London), 28g of Upper 

 Greensand, and 1S8| of Gault, at the depth of 1081 1 feet hard 

 limestone, mostly with rather large oolitic grains, was met with. 

 This, with alternations of a finer character, sandy and clayey, lasted 

 for only 38| feet, being much less than the thickness of the Jurassic 

 beds, either at Eichmond or at Meux's boring. The general 

 character of the cores showed a likeness to the Forest Marble, and the 

 occurrence of Ostrea acuminata agreed therewith. 



