122 Scientific Intelligence. 
method of observation had been applied to North Wales; and it had 
been ascertained that in the Pass of Llanberris the grooves and round- 
ings of the rocks extended to a height of 1,300 feet above the present 
bottom of the valley. The drifted deposits which overlie these rounded 
surfaces must have formed during the slow depression which followed, 
and the glaciers bit still have existed, since these deposits, though 
marine, are stil a moraine character. The cold climate continued 
during the poned: of depression, and for some time after it ; and there 
was beautiful evidence in the side valleys of the gradual decrease 
of the glaciers until they died away amongst the higher mountains, in 
the form of moraines stretching across the valleys, one within the other. 
The scratches made by the first set of glaciers passed down the val- 
leys; those of the smaller glaciers crossed the first obliquely. 
4, On the Foliation of some Metamorphic Rocks in Soottantté by 
Prof. E. Forzss, (Ibid.)—It was of great importance to geologists to dis- 
tinguish between lamination, cleavage, and foliation: the first resulted 
from original planes of deposition: the second was a superinduced 
structure, dividing rocks into lamine of similar constitution, not colnci- 
~ with the lines of bedding; thirdly, foliation was the division of a 
ock into lamin of different mineral condition. Cleavage had been 
atest, by Prof. Sedgwick, its first definer, to electrical action; by 
Mr. Sorby, to a mechanical Siena and by Mr. D. Sharpe, to mechanical 
and chemical influence. The foliation of mica she or separation of 
its mineral constituents into distinct layers, had been sometimes poet 
ted to metamorphic action on layers of different er ; Mr. Dar 
win bad considered it identical with cleavage, and due to the same 
ause,—the one passing into the other: the same view has been main- 
tained by Mr. Sharpe. Prof. Forbes agreed with those who considered 
The author then referred to examples of foliated structure. In a roaa- 
side quarry at Crianlarich, near the head of Loch h Lomond, where the 
metamorphism of bands of fossils. In the upper part of the quarry the 
limestone becomes foliated with mica,—the foliation being at first paral- 
Jel with the bedding, then becomes wavy and contorted, is affected by 
small faults, and contains nuclei of calcareous spar and at length passes 
into a mica slate. At Ben Os there is a calciferous band in the mica slate, © 
ation curves round 
