TRANSACTIONS OF THE SECTIONS. 101 
up through the strata, both of mica-slate and of carboniferous sandstone and lime- 
stone, and resting on the latter in vast beds. The igneous rocks, mixed with frag- 
ments of sandstone and altered limestone, form a broad band across the country from 
the coast near Losset to Macharioch, in the region coloured by Macculloch as mica- 
slate. They are evidently of very diverse ages, veins of one kind often intersecting 
masses of another. Thus, at Kilchousland, a vein of dark greenstone, divided into 
nearly horizontal columns, intersects a mass of light gray trap, often highly concre- 
tionary, and in one place forming vertical columns, tike a miniature Giant's Causeway, 
the intervals between the prisms being filled with veins of calcspar, haematite and 
malachite. 
The next deposit is the red boulder clay or till, containing striated blocks, and 
forming low hills in the Laggan of Cantyre. On this rests shingle beds, composed 
of rounded water-worn stones, gravel and sand, usually more or less stratified, and 
forming several low terraces. In the hollows among these masses, beds of peat con- 
taining large trunks of trees, apparently oak and birch, with nuts and leaves of the 
hazel, alder and other trees, occur, resting on red clay, and overlaid by other beds of 
white and red clays. This deposit seems lacustrine, and resembles the recent tertiary 
beds with lignite on the coast of Norfolk, with which it probably agrees in age. The 
lake was perhaps drained during the recent elevation of the land, marked by a line 
of cliff round the whole peninsula. In this cliff are many large caves, of which two, 
130 feet long and meeting in the interior, cut in the hard porphyry of Davar island, 
show the long period the sea must have remained at its former level. 
Some of the general results of this investigation are interesting. The peculiar 
arenaceous character of the mica-slate intermediate between the crystalline rocks of 
the north Highlands and the Silurian beds of the south of Scotland, the amount of 
limestone beds in some parts of the series, the diversity in its dip and direction from 
the mica-slate of the more northern Highlands, indicate that it belongs to a different 
group. Ina paper read to the Geological Society of London, the author formerly 
‘stated that the mica and clay-slates on the southern border of the Grampians were 
probably the northern synclinal of the great trough in which the central coal-fields 
of Scotland were deposited, and ef which the Silurian strata of the south were the 
cther side. These beds are chiefly of lower Silurian age, and hence the author 
infers that the metamorphic schists of Cantyre are probably altered Upper Silurian 
or Devonian strata, and that the great mica-slate formation of the Scottish High- 
lands will eventually require to be divided into several subordinate groups. The in- 
troduction of the large overlying mass of trap and sandstone, covering many square 
miles cf the region coloured by Macculloch as mica-slate, renders this part of Can- 
tyre closely analogous to the south of Arran. It also completes the great band of 
trap, which; commencing on the shore of the German ocean near Montrose, is now 
seen to extend across the whole of Scotland to the Atlantic, and even into the north 
of Ireland. 
On the Gradual Subsidence of a Portion of the Surface of Chat Moss, in 
Lancashire, by Drainage. By G.W. Ormerop, W.A., F.G_S. 
This paper was in continuation of a communication to this Association, made by 
Mr. Ormerod at the Swansea meeting, The result of a series of levellings taken 
by Mr. Ormerod during the last four years over an extent of about 200 acres, where 
drainage was carried on, proved an average subsidence at the rate of one foot per 
annum. atts» $i 
Notice of the manner in which Trap or Igneous Rocks intrude into the Sand- 
stone and Conglomerate near North Berwick. By Lt.-Colonel Porttock, 
R.A., FBS, Pres. Geol. Soe. of Dublin. 
Lieut.-Colonel Portlock observed that two classes of phenomena engage the atten- 
tion of geologists,—Ist, the vital phenomena of the earth as exhibited in the organic 
Temains of its past inhabitants ; 2, the physical phenomena, as exhibited in the effects 
produced by the action of igneous rocks, and of other agents. 
It was his object to draw attention in a few brief remarks to the latter, as they were 
