CIIAPTEK XXVIII 
ILLUSTRATIVE EXAMPLES OF THE CARBONIFEROUS PUTS OF SCOTLAND 
The Basin of the Firth of Forth — North Ayrshire — Liddesdale. 
Though many of the geological details of each of the Scottish districts of 
Puys have been given in the foregoing pages, it will be of advantage to 
describe in connected sequence the structure and geological history of a 
few typical areas. By far the fullest and most varied record of this phase 
of volcanic activity has been preserved in the basin of the Firth of Forth ; 
but the north of Ayrshire and tlie district of Liddesdale furnish also many 
interesting characteristics. 
1. BASIN OF THE FIRTH OF FORTH 
Eeference has already been made to the remarkable peculiarity in the 
development of the lower part of the Carboniferous system in this district.' 
LIsewhere throughout Scotland the Cement-stone group and the plateau 
lavas are immediately overlain by the Carboniferous Limestone series. But 
in the basin of tlie Firth of Forth a varied succession of strata, more than 
3000 feet in thickness, intervenes between the Cement-stones and the 
Hurlet Limestone. The lower portion of this thick mass of sediment may 
represent a part of the Cement-stone group of other districts, but even ii 
some deduction is made on this account there remain many hundred feet of 
stratified deposits, for which there does not appear to be any stratigraphical 
equivalent elsewhere in Scotland. The distinguishing features of this series 
of strata are the thick zones of white sandstone, with occasional bands of 
fine conglomerate, tlie abundant seams of dark shale, often highly carbonaceous 
(oil-shales), the cyprid limestones and the seams of coal. Such an association 
of deposits may indicate a more humid climate and more varied conditions 
of denudation and deposition than are presented by the typical Cement-stones. 
The muddy floor of the shallow water must, in many places, have supported a 
luxuriant growth of vegetation, which is preserved in occasional seams and 
^ See Maclareu s “Geology of Fife and the Lotliiaiis,” the 3Icnioirs of the Geological Survey of 
ScoUnml, on Sheets 31 and 32, and my Memoir, already cited, Trans. Itov. Soc. Edin. vol. xxix. 
(1879) 13. 437. 
