263 
1911 - 12 .] Eeport on Rock Specimens. 
great divisions into which geologists have classified rocks, viz. (a) Sedi- 
mentary, ( b ) Metamorphic, and (c) Igneous. 
(a) Sedimentary Rocks . — Many of the sedimentary rock-specimens 
contain characteristic fossils, and their relative geological age can be 
determined with certainty, while many others can be classified by their 
lithological peculiarities with a considerable amount of accuracy and even 
their probable source indicated. 
A group of over forty specimens of greenish-grey greywacke sandstones, 
dark shales, and black lydian-stone, identical in lithological character with 
rocks that floor a large portion of the Southern Uplands of Scotland and the 
northern central part of Ireland, may with considerable confidence be 
referred to the great Silurian Formation, though no fossils were found in 
them. Of these, twenty -three specimens (48'93 per cent.) are well glaciated 
(Plate L figs. 1 and 2), six (12 76 per cent.) subangular and ice-moulded, 
seven (14*9 per cent.) rolled and well rounded (Plate II. figs. 1-6), and only 
eleven (23 - 6 per cent.) angular. 
To the Devonian formation are to be assigned four specimens of purple 
conglomeratic grits, with stained quartzite and acid igneous pebbles, 
identical in lithological character with some of the “ Glengariff Grits ” of 
the Dingle Peninsula in the south-west of Ireland. These specimens show 
irregular fracture faces and are not glaciated, nor did they yield any 
organic remains. 
Carboniferous rocks are well represented by over forty specimens 
ranging from 44 to 2 inches in diameter. Sixteen of these are of lime- 
stone and calcareous shales with encrinites, and two are of limestone with 
chert, all of types identical with rocks in situ in Galway, Clare, and the 
centre of Ireland. One sandstone fragment was met with, crowded with 
species of Schizodus and Edmondia in the manner in which they occur in 
the Lower Carboniferous rocks of the Solway region of southern Scotland, 
and Londonderry and Tyrone in Ireland (Plate III.). 
The other specimens are chiefly sandstones and sandy shales, many of 
which contain plant remains, and one with Spirorbis carbonarius. A few 
fragments of yellow sandstone and sandy shale like the above but without 
plants, doubtfully included with the Carboniferous rocks, could be matched 
from almost any Carboniferous area in Britain or Ireland. 
Most of the limestone fragments show traces of having been glaciated ; 
only one is well rolled, and three specimens, including those with chert, are 
angular. Of the sandstones and sandy shales the larger proportion have 
been glaciated, one is rounded, only three are angular, and a few are too 
friable to afford evidence as to their original condition. 
