448 PROFESSOR GEIKIE ON THE 
occurs on the headland of St Baldred’s Cradle (fig. 6), and several may be 3 
observed near Dunbar.* Again, on the south side of the volcanic sheets, a con- 
spicuous neck rises in Traprain Law. As no necks appear among the hills to 
the south, nor among the red sandstone to the east, it is evident that the cones 
from which the volcanic mass of East Lothian was poured out formed a con- 
nected group in the shallow water at the northern base of the heights of 
Lammermuir. The lava and tuff occupy nearly the whole of the interval 
between the red sandstone group and the base of the Carboniferous Limestone 
series. Volcanic action was thus prolonged in East Lothian for a protracted 
period after it had died out in the Edinburgh district. 
3. West Lothian District.—It is remarkable that while on the east side of 
Arthur Seat and the Pentland Hills not a single volcanic eruption, so far as 
we know, took place on the Mid-Lothian area during the whole of the Carboni- 
ferous period, the ground to the westward continued to be dotted with active 
vents throughout the deposition of the Calciferous Sandstones and Carboniferous 
Limestone series. The oldest eruptions of which any trace can be seen pro- 
ceeded from small cones, chiefly of tuff. Towards the close of the Calciferous 
Sandstone period the volcanic activity increased. At the same time, the cones 
extended northwards into Fife. Some of them were of comparatively large 4 
size. The Binns Hill of Linlithgowshire, for example, which still forms a _ 
prominent elevation, rising to a height of 170 feet above its base, consists of a j 
mass of fine green tuff, at least 350 feet thick, the vent being now filled up witha 
plug of basalt, which forms the summit of the hill. South-westwards from Binns 
the volcanic cones were grouped more closely together, and continued to throw _ 
out both showers of tuff and streams of basaltic lavas. These volcanic materials — 
were interstratified with the ordinary sandstones, shales, and other strata of the * . 
Lower Carboniferous groups. The Burdie House limestone and Houston coal- 
seam may be traced among them. We can also detect some of the lower q 
thick calcareous zones of the Carboniferous Limestone series, charged with 
corals, crinoids, and other characterstic fossils. But along one special tract the 
volcanic sheets so increased in bulk that at last a great bank of lava stretched 
continuously between Linlithgow and Bathgate, and prevented the deposition — 
of a considerable portion of the coal-bearmg section of the Limestone 
series, which is consequently not represented there, its place being taken by — 
volcanic rocks. The general depression, however, that led to the formation — 
of the thin upper limestones seems to have been accompanied here by a 
cessation of volcanic action, The latest interbedded lavas and tuffs lie almost 
immediately below the Calmy Limestone. Volcanic interstratifications die 
out there, and save in the form of intrusive masses to be immediately 
referred to, never reappear in any later formation in this district. 
4 
OCA VY to verve 
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* See “Memoir on East Lothian,” Geol. Survey Memoirs, chap. v. 
