CARBONIFEROUS VOLCANIC ROCKS OF THE FIRTH OF FORTH BASIN, 445 
much later eruptions. In the east of Fife they have been accompanied by 
large sheets of tuff which repose unconformably on the upper Coal-measures 
and the Carboniferous Limestone series, spreading over faulted and much 
denuded ground. They must thus either be post-Carboniferous, or at least 
faust be separated from the highest remaining portion of the Carboniferous 
rocks by an enormous interval of time. Though I believe them to be post- 
Carboniferous, some probably of Permian, others possibly of Miocene date, I 
have judged it best to include them in the present communication. The Coal- 
measures, save where covered by these later volcanic sheets, have nothing 
overlying them but the drifts and other superficial accumulations. 
B. Vo.ucanic DISTRICTS. 
Notwithstanding the limited extent of the Basin of the Firth of Forth, 
_ the sporadic character of its volcanic phenomena is singularly striking. Six 
districts can still be traced, each marked by its own independent eruptions, 
which differed from those of the neighbouring tracts not only in time, but 
even in petrographical character. These districts may be distinguished by 
the following topographical names:—1, Edinburgh; 2. East Lothian or 
Haddingtonshire; 3. West Lothian or Linlithgowshire; 4. Stirlingshire; 5, 
West Fife; 6. East Fife. (See Plate IX.) 
1, Edinburgh District.—The interbedded volcanic masses of this district 
are confined to the near neighbourhood of Edinburgh, where they form the 
well-known eminences of Arthur Seat, Calton Hill, and Craiglockhart Hill. 
They consist both of lavas and tuffs, in beds varying from 10 to 50 feet or 
more in thickness. Their eruption began about the close of the red sandstone. 
group, at the base of the Carboniferous system in Scotland, for their higher 
beds are intercalated with and covered by the lower portion of the white 
sandstone and dark shale group of the Calciferous Sandstones. This epoch was 
one of great volcanic activity over the southern half of Scotland. During its 
continuance there were erupted the lavas and tuffs of the Garlton Hills in 
Haddingtonshire, those which range along the southern flank of the Silurian 
uplands from near Dunse in Berwickshire, by Kelso, Rubers Law, Langholm, 
Birrenswark, and the Annan, to the mouth of the Nith at the foot of Criffel, 
To the same period of volcanic activity must be assigned the older parts 
of the great sheets of lava and tuff which extend through the north of Ayr- 
shire, Renfrewshire, and Dumbartonshire, by the Kilpatrick and Campsie Fells 
to Stirling. 
Throughout most of these volcanic tracts the lavas were chiefly the so-called 
“porphyrites,” and the tuffs were dull-red or greenish rocks derived from the 
VOL, XXIX. PART I, - 5Y 
