TRANSACTIONS OF THE SECTIONS. 95 
bed of brick clay seems to have been frequently subjected both to ele- 
vation and subsidence ; the latter condition being more difficult to ob- 
serve, from its being often beyond our view. The brick clay of the 
neighbourhood of Glasgow appears also to coincide in age with the 
Carse clay of the east of Scotland, as may be seen in the valley of the 
Tay, where a singular phenomenon is presented by a bed containing 
stumps of trees, which is covered by another containing littoral shells. 
He mentioned, that Dr. Thomson, of Glasgow, had recorded a whin 
dyke that penetrated the superficial sand of that city, but he was not 
aware of the sand having been altered by it; also, that in Cumbrae a 
great wearing away of the sandstone was proved by the dykes, as they 
were now presented to the observer: allowing a foot in the century for 
this destruction, it would require many centuries to effect what has been 
done, which induced Mr. Smith to consider the post-tertiary period to 
be much longer than is generally supposed. 
——____ 
On the Geology of Castle Hill, Ardrossan. By Wiiu1aM Kerr. 
It is situated at the north-west extremity of the great Scotch coal 
field. On the north side of Ardrossan quay may be seen the old red 
sandstone dipping. beneath the coal; the pier is built on a trap dyke, 
and the baths upon another; between them the coal strata run into 
the sea at angles highly inclined. The Castle Hill is formed by an 
eruption of trap, chiefly in the condition of claystone and clinkstone, 
with a vein of green serpentine running through it, without rising to 
the surface. In cutting for the railway, this vein has been exposed 
and a portion removed. At first it was dark green, very brittle, and 
frequently coated with steatite; it then became darker in colour, and 
more compact, and is now becoming like ordinary greenstone. The 
claystone of the hill appears to have been fissured by the eruption of 
the serpentine; the fissures are filled with drift, in which are many 
fragments that bear such marks of fusion as to resemble scorie ; they 
have often a ceiling of stalactite, and a floor of stalactitic conglome- 
rate, formed of water-worn pebbles and recent sea-shells, proving the 
elevation of the rock, the cavernous part being thirty feet above the 
present tide-level. A little higher, in a sheltered spot, is a bed of re- 
cent shells, Littorina vulgaris and Patella vulgaris, which have been 
brought there in storms. 
—_—_ 
On the Granite Formations of Newabbey, in Galloway. By the Rev. 
J. M. Fisuer, A.M, of Rose Bank, Dumfries. 
“The parishes of Newabbey, Kirkbean, Colvend, and Kirkgunzeon, 
lie contiguous, and the chains or ridges pervading these, which are 
wholly composed of granite, stretch in a direction from S.E. to N.W. 
The granite, it is true, appears more distinct in the above-mentioned 
parishes ; still it stretches in a sort of ridge across the south of the 
