265 
1911-12.] Report on Rock Specimens. 
and (2) a set consisting of both sedimentary and intrusive igneous rocks 
of low-grade metamorphism. 
(1) There are nineteen gneiss fragments, seventeen of which are ice- 
moulded and glaciated, the other two being angular. The largest is about 
4 inches, the rest being of nearly uniform size, between 2 and 3 
inches in diameter. They contain orthogneisses (foliated igneous rocks), 
like most of the Lewisian gneisses, and paragneisses (metamorphosed 
sediments), like the muscovite-biotite gneisses and quartz-biotite-granulites 
of the Moine series of Scotland. Rocks of this type make up a large part 
of the north of Ireland and floor large tracts of southern Scandinavia. 
Dr Flett sends the following note on his examination of the microscopic 
slides of the gneisses referred to : — 
“ Among the gneisses sliced, several are of distinctly Lewisian type. 
They are (57)* pyroxene-gneiss, (61) epidotic hornblende-gneiss; (55) 
biotite-hornblende-gneiss ; (59) biotite-gneiss [orthogneiss] ; (58) muscovite- 
biotite-gneiss. Two others are distinctly like the coarser gneisses of the 
Moine series. They are (56) biotite-gneiss rather crushed, and (60) biotite- 
gneiss or granulite somewhat coarse-grained. (54) is a granulitic gneiss 
which has more resemblance to the Moine rocks than to the Lewisian. All 
these rocks could be matched in the North-West Highlands [of Scotland] 
without any difficulty. (62) is a sericitic granite-gneiss of doubtful origin.” 
(2) The specimens to the number of twenty-one that come under this 
heading are more varied in character than the gneisses. One small 
glaciated fragment, 2J inches in diameter, more altered than the rest, is a 
puckered black graphitic schist like that occurring along the belt which 
traverses the Central Highlands of Scotland and is continued into the 
Donegal Highlands of Ireland. Similar rocks also occur in Connemara. 
The most conspicuous type of rock is a green lustrous puckered slate 
or phyllite, showing that it has been subjected to pressure in more than 
one direction (as shown in Plate V. fig. 1). There are eight specimens, 
varying from 2 to 5 inches in longest diameter. They are for the most 
part flat and thin, showing foliation and joint faces, and with sharp corners 
and edges. Two thicker specimens are glaciated, one of which is only a 
part of a broken-up boulder. 
Two small angular specimens of blue slate show that their cleavage is at 
right angles to the bedding planes. One piece of purple slate is glaciated. 
Four fragments of flaser greywacke or grit, one of which is glaciated, 
and an angular specimen of coarse pebbly grit or conglomerate, make up 
the tale of schists of sedimentary origin. 
* The numbers refer to those of the thin slices. 
