On. the Physical Geolog y of the Neighbourhood of Dublin, 157 
larger or Lower Lough Bray (elevation 1,225 fect) is dammed in 
by a glacial moraine, the two arms of which meet at the bottom 
of the lake and then descend towards the bottom of Glencree 
valley, near the head of which the lakes are situated. Their 
lower parts below the lake are covered with numerous large 
granite blocks, some of which must weigh about 200 tons. That 
part of the grounds of Lough Bray Cottage which is on the N. 
side of the lake is on a bank leaning against the hill side; the 
upper side of this bank falls to the hill side. The lower eastern 
end of the bank is beneath the water of the lake. This is clearly 
a latero-terminal moraine formed by the glacier when it had 
shrunk so as to be unable to fill the original moraine bed it had 
made for itself. (The jointing of the highest part of the precipice 
is well seen from the ground between the two lakes. In the 
lower part of the precipice the primary jointing dips inwards, 
and is as recular as stratification ; at the summit it is horizontal.) 
The small Upper Lough (elevation 1,455 feet) might be con- 
sidered by some the more interesting, glacially, of the two. 
It is contained in its own recess which is much less deep 
than that of the Lower Lake. If we may so express it, 
the width of the Upper Lake is greater than its length. 
Its longest axis is parallel to the cliff under which it lies and to 
the moraine dam. This dam is a well defined bank running all 
along the lower edge of the lake; at its middle part it rises about 
90 feet above the water. It is represented, but without the 
following small details, on the shaded Ordnance inch map, 121. 
All along its top runs a small, very distinct, ridge or crest, which 
looks almost like an artificial bank, and close outside of this, for 
the S.E. half of its length runs a second parallel but not so 
regular crest. Several huge blocks of granite are scattered about 
on this moraine dam ; one lies right on the first mentioned crest. 
Some of these must be 200 tons in weight; the largest (on the 
outer side of the moraine) measures 28 feet in width at its base, 
26 feet in height, with a mean thickness of about 9 feet ; it must 
weigh at least 250 tons. These blocks have, no doubt, come 
from the cliff on the opposite side of thelake. It is interesting 
to have this evidence of so great power in so small a glacier. No 
rock-scoring is to be seen ; tHe rocks being all concealed by the 
moraine masses, except in ‘the precipices over the lakes, 
