a eee eee 
TRANSACTIONS OF THE SECTIONS. 93 
the north and south boundaries of the old red sandstone, between 
Fallen Rocks and Corrie, it assumes a conglomerate form; but before 
passing into the coal measures, we find the same pebbles, of which it 
is composed, inclosed in lime, forming a carboniferous limestone con- 
glomerate; after which succeed the various sandstones, limes, and 
shales of the coal formations. It is equally impossible to define the 
boundaries of the coal measures and the new red sandstone. As, 
therefore, there is no sudden change from one set of rocks to the 
other, Mr. R. inferred that they were regularly laid on each other, 
without any material intervening change having taken place in the bed 
of the sea where they were deposited. 
On the question, through what agencies did these strata attain 
their present elevation, the author states the following facts :—There 
are no fragments of granite in any of the overlying formations. 
Granite often penetrates the slate in veins, but has nowhere over- 
flowed the slate. Probably, before the deposition of the old red sand- 
stone, the melted granite was formed under the slate, partially eleva- 
ting it above the water and cracking it in many places. Into these 
fissures the granite infused itself, cooled, and was subsequently up- 
heaved and protruded in its present crystalline form. In proof of this, 
it is stated—Ist, that rounded fragments of slate and schist are im- 
bedded in the old red sandstone ; 2nd, that in many places a shallow 
valley intervenes between the highest point of the slate and the central 
granite; 3rd, the separated edges of the slate dip towards the granite ; 
4th, had the sandstone rocks completely overlaid the slate before its 
first partial elevation, they would have occupied the low ridges which 
now encircle the granite. 
There are in Arran two granites distinct in character, the one coarse 
and erystalline, the other of a finer and softer texture. The fine granite 
occupies the centre of the granitic district, the coarse forming the 
external ridges next the slate. The fine granite also penetrates the 
coarse variety in veins. Trap and pitchstone dykes penetrate the 
coarse granite in many places; but as no dykes have yet been found 
in the fine granite, and as these dykes are always cut off by the fine 
granite when they approach it in the coarse rock, it would appear that 
the fine granite is even newer than the trap dykes; and if these last 
are contemporaneous with the traps and porphyries of the south end of 
Arran, the fine granite must also be of later origin than they are. In 
the year 1837, Mr. Ramsay discovered a mass of fine-grained granite 
to the west of Glen Cloy (called by M. Necker, who noticed it last 
year, Ploverfield) associated with syenite, and sending veins into the 
adjacent red sandstone. 
With regard to the more recent elevations, the author stated, that an 
ancient sea cliff, the foot of which is about forty feet above the level 
of the sea, surrounds great part of the island, and, gradually sloping 
from this to the modern beach, shells are found similar to what are 
now found on the shore. These shells are even found at the entrances 
of the water-worn caves so common in this cliff; and these caves, 
instead of lying horizontally, dip agreeably to the anticlinal line, their 
