8 Keegan: The Rocks of Patterdale (Ulswater). 
would be extremely satisfactory. The general structure is un- 
doubtedly that of an andesite, but the large felspar crystals, 
though well formed and long and narrow, are not tabular (as 
in the Silver Hill rock); some of them when fresh would doubt- 
less have shown clear twinning on the albite plan; there are also 
a few well-shaped crystals of a bright emerald green chlorite 
after augite; the ground-mass is dark and dusty and liberally 
infiltrated with iron; nevertheless there are very decided remains 
of a felted aggregate of large and lengthy felspar laths. The 
whole rock is greatly corroded, and so lavishly dusted and 
bespattered with ferruginous matter (there are several hema- 
tite veins close at hand), that we must rest content with the 
endeavour to recall what must originally have been a very 
beautiful and interesting structure, The section from near the 
se of Annstone Crag has a somewhat similar appearance to 
that from the summit, but there is comparatively little iron; the 
large felspars are altered to See and have large patches of 
a very pale chlorite matter; the und-mass is very light in 
colour, with the outlines of the eanonac aths very clearly 
discernible in many places, and the whole intervals between — 
these diffused with a pale green chloritic at Passing on to 
Hall Bank our researches, enter somewhat debateable ground. 
A section of the rock which flanks the main valley is of a very 
indefinite character ; the ground-mass is very fine, and there are 
_a number of what once have been large crystals; but the whole | 
structure is very ferruginous and dubious, so that whether it is a 
lava or a sort of ash conglomerate is very difficult to determine. 
The conspicuous cliff which forms the lake-side shoulder of © 
: Stybarrow Crag is formed of a very hard rock... Accor ding to 
_ the Geological Survey Map it is set down as a voleanic ash and 
breccia, or a bedded slate; but I am inclined tonthink that it 
is a lava somewhat akin to the specimen described above from 
| Angle Tarn Gill, but with the difference that here the felspar — 
—laths in the ground-mass are more numerous and more easily 
A distinguishable. The principal feature about the rock, however, | 
; is its flinty and uncleavable character; and it is. readily seen 
that large veins of clear quartz have extensively penetrated its 
substance, imparting to it a compactness and toughness which 
; (are not common among the rocks in the neighbourhood, and, 
a had far as I know, are confined to the lavas exclusively. 
e will now endeavour to describe the volcanic ash. of ; 
pati a by no means easy matter. It is not so abundant 
~ meh, Be. pour but is. well “developed in a SRY o 
