1882 .] 
3B9 
[Davis. 
Certain lakes of moderate size in north-western England are con- 
sidered by Ward 1 to be deepest at points where from confluence 
of lateral glaciers and narrowing of the valleys, the pressure must 
have been greatest; he shows also that the amount of erosion 
required to form these lakes is very small, but he does not estimate 
the share of lake formation that may come from barrier deposits 
in the old valleys, and this cause would reduce the necessary 
glacial erosion still more. 
Haast attributes much effect to a reaction from the terminal 
moraines : 2 when a strong terminal moraine is formed and consol- 
idated by infiltration of glacial mud, its opposition to an advance 
of the glacier would cause the ice to press harder upon the valley 
bottom, and so cut out a basin. It remains to be proved, however, 
that the lakes he maps and describes are really in rock-basins and 
not simply dammed back by moraines still more, that the gla- 
ciers made any attempt to advance over the terminal moraines 
where they seem to have halted contentedly so long. 
According to some, lakes mark the position held for a time by 
the end of the ice : this implies that erosion progressed faster 
beneath the whole length of the ice than in the open valley below, 
so that when the glacier melted away, water would collect just 
above the junction of the two styles of erosion. For Switzerland, 
the evidence of this is very contradictory ; the Italian lakes might 
seem to confirm it, but the proof that they are neither barrier 
lakes nor warped valleys is wanting; moreover the neighbor- 
ing valleys of the Dora Iiiparia and Dora Baltea, which led 
great glaciers down from the Alps to the Plain of the Po, have 
no lakes at all comparable to Maggiore and its fellows . 3 On the 
northern slope of the Alps, the placing of most of the lakes is 
1 Geol. Soc. Journ., xxx, 1874, 101; xxxi, 1875, 152-166. 
2 Notes on the Causes which have led to the excavation of deep Lake basins in 
Hard Rocks in the Southern Alps of New Zealand. Geol. Soc. Journ. xxi, 1865, 130- 
132, and also 133-135. 
3 Favre, loc. cit. 211. Gastaldi thinks these valleys were occupied by lakes when 
the glaciers melted away, but they have since been filled by alluvium. Sulla riescava- 
zione dei bacini lacustri per opera degli antichi ghiacchiai. Milano, Soc. Ital. Mem., i, 
