CHAV, xxvn 
BURIAL OF THE BUY- CONES 
433 
rose above the level of the water, the vent became subicrial. An instance 
of a submarine vent has been cited from the Perthshire coal-field (p. 426). 
Among the evidence which may lie collected to show that some 
Carboniferous volcanoes probably rose as insular coiies of tuff above the 
surrounding waters, the structure of the tuff in many necks may be 
cited, for it suggests subrerial rather than subaqueous stratification. The 
way in which tlie stones, large and small, are grouped together in 
lenticular seams may be paralleled on the slopes of many a modern 
volcano. Another indication of this mode of origin is supplied by the 
traces of wood to be met with in some of the tulT - necks. The 
vents of Fife and Linlithgowshire contain these traces sometimes in 
great abundance. The specimens are always angular fragments, and are 
frequently encrusted with caleite.^ Sometimes they present the glossy 
fracture and clear ligneous structure shown by sticks of well - made 
wood charcoal. In a neck at St. JMagdalen’s, near Linlithgow, the wood 
fragments occur as numerous black chips. So far as can be ascertained 
from the slices already prepared for the microscope, the wood is always 
coniferous. These woody fragments seldom occur in the interstratified tuffs 
or in the associated strata where Stigmaria, Lcpidodendron, etc., are common. 
They are specially characteristic of the necks and adjacent tuffs. Tlie 
parent trees may have grown on the volcanic cones, which as dry insular 
spots woidd support a different vegetation from the club-mosses and reeds 
of the surrounding swampts. As the fragments occur in the tuffs which, on 
the grounds already stated, niay be held to have been deposited within the 
crater, they seem to point to intervals of volcanic quiescence, when the 
dormant or extinct craters were filled with a terrestrial flora, as Vesuvius 
was between the years 1500 and 1631, when no eruptions took place. 
Some of the cones, such as Saline Hill and the Biuu of Burntisland, maj’ 
have risen several hundred feet above the water. Clothed with dark pine, 
woods, they would form a notable feature in the otherwuse monotonous 
scenery of central Scotland during the Carboniferous period. 
Enkmibmmt of the Volcanic Cones and their relation to the oedded Lavas 
and Tuffs. — From the facts above detailed, it is evident that in most cases 
the necks repiresent, as it were, the mere denuded stumprs of the volcanoes. 
As the p)uys took their rise in areas which, on the whole, were undergoing 
a movement of subsidence, they were eventually submerged and buried 
under sedimentary accumulations. Their loose ashes would be apt to be 
washed down and strewn over the sea-bottom, so that only the lower and 
inner part of a cone might remain. We can hardly hope to discover any 
of the actual craters among these volcanic relics. The cones having been 
submerged and buried under many hundred feet of sediment, their present 
position at the surface is due to subsequent elevation and prolonged denuda- 
tion. It is obvious that there must still be many buried cones which the 
progress of denudation has not yet reached. Some of these have been 
^ The largest I have observed is a portion of a stem about two feet long and six inches broad, 
in the (Permian ?) neck below St. Monan’s church. 
VOL. I 2 F 
