44 
THE GEOLOGIST. 
Axis. 
\ 
S.S.E. 
3. I'pper Lanarlvsliire coal measures : — j 3. Sandstones, shale, and a bed of coal. 
^^ hoUy fluviatile organic characters. 
2. Beds of marine and fluvio-marine lime- 
stone intercalated with shale, coal, 
ironstone, and stratified trap. 
1. Shales, sandstones. 
2. Freshwater limestone. 
1. Shale, sandstone, tufa. 
On the Bathgate Hills the niarine limestone is sixty feet thick, 
and the fluviatile limestone about twenty feet thick. But towards 
the south-west, on the borders of Edinburgh and Lanarkshires, the 
marine limestone thins into beds of from three to six feet thick, 
whilst the freshwater bed is above fifty feet thick. 
The Torbane Hill bed lies in number two of the left-hand series 
of strata. Along with two or three local coal-seams, it occupies a 
small mineral basin some two or three miles in area, lying immedi- 
ately above the mountain-limestone, but stratigraphically distinct 
from the upper Lanarkshire coal-measures. The petrological struc- 
ture of the surrounding strata is very unique ; let us try to evolve 
their history. 
The physical changes closing the life-era of the Scottish old red 
sandstone system are difficult to determine. From various geolo- 
gical reasons, the chief of which are the wave-ripples ou the sand- 
stones, and the physical structure of the surrounding mountain-chains, 
it has been deduced that central Scotland was a strait or frith bounded 
as now by the prominent peaks of the northern and southern High- 
lands. Islets, covered by a strange vegetation, dotted this watery ex- 
panse ; from the eastward strong currents brought down the spoils of 
a now lost land, depositing the shales and sandstones so predominant 
round the Scottish metropolis. In this quarter, too, an intense vol- 
canic activity prevailed. 
The trappean bosses, which form so prominent a feature in the 
landscape round Edinburgh, were mostly erupted at this time. So, 
at least, the labours of Mr, Geikie and others go to prove. 
Erom St. Abb's Head to Bathgate a chain of volcanos sent up their 
lurid contents into the Carboniferous sky. Nowhere was this activity 
more intense thm on the Bathgate hills. The freshwater series to 
the eastwards of our section are everywhere intercalated with trap ; 
some of it developed as aerial ash-beds, the rest as submarine green- 
stones. The prominences round Winchburgh, Binny, and Linlithgow, 
which the raihvay-traveller may remember so boldly characterize the 
scenery, are the memorials of these eruptions. The spot pointed out 
as the axis of the hills was undoubtedly the vent of a very active vol- 
cano. Immediately above Bathgate four or five great beds of basaltic 
greenstone and ash lie so intercalated with the aqueous strata as to 
