3G2 
Proceedings of the Boyal Society 
tance, as well as by masses of ice from the adjacent shores dropping 
their loads of mnd, earth, and stones to the bottom. The lower 
Boulder-clay or till, on tlie other hand, seems to have gathered 
partly on the land, and partly under the ice-sheet which pushed 
its way out to sea.* This took place when the land was under- 
going a submergence, so that the lower Boulder-clay might be 
accumulating on the land and along the coast-line, while the upper 
part of the deposit was being formed from the droppings of floating 
ice some way further out at sea. The following tables give the 
percentage of stones in the two clays on the line of the new rail- 
way near Newhaven, and show the markedly local character of 
those in the lower zone, and the mixture of erratic boulders in the 
upper : — f 
JJypeT Rudely Stratified Clay (near Man-Trafi), 
Mica-schist, 
Per cent. 
. 6 
Purple cleaved slate. 
. 1 
Metamorphic grit. 
. 2 
From the Ochil Hills, 16 per cent. 
Bed felstoiie, 
. 2 
Pink „ 
. 2 
Blue „ . . 
. 1 
Purple „ 
. 1 
Pink porphyry. 
. 4 
Purple ,, 
. 2 
G-reen „ 
. 1 
Bed felspathic sandstone. 
. 2 
Felspathic conglomerate. 
From the Carboniferous rocks of the 
Basin of the Forth, 63 per cent. 
Per cent. 
White and grey sandstone, 25 
Black shale, . . .8 
Ironstone, . . .8 
Coal, . . . .6 
Basalt, . . . .2 
Grreenstone, . . .9 
Ash, . . . . 1 
Cement stone,, . . 1 
Cyprid limestone (= Queens- 
ferry or Burdie House), 1 
Cyprid shale, . . .2 
Doubtful ; either from the Ochils 
or from the Lower Carboni- 
ferous rocks, 12 per cent. 
Quartz pebbles, . . 9 
Quartz-rock pebbles, . . 3 
® This view of the origin of the till was proposed by me in October 186 
and published in the following spring in my “ Memoir on the Phenomena of 
the Glacial Drift of Scotland,” and a woodcut was there given (p. 99) to 
show how the deposit might contain the remains both of land plants and of 
sea-shells. 
t These percentages were taken in September 1863, in company with my 
colleague. Dr Young. 
