Transactions. 103 
COMMUNICATIONS. 
I. The Lower Carboniferous System in Dumfriesshire. 
By Mr James Darron, F.G.S. 
It may be recollected that the last papers I read before this 
Society were upon the Silurian System, with its graptolites, so 
celebrated for their abundance, and also the beautiful state of 
preservation in which they are found around Moffat. Among 
the numerous places, both here and abroad, I have seen nowhere 
that can surpass Dob’s Linn, in Dumfriesshire. I have thought 
it might be acceptable to make a change for the night to the 
carboniferous system. It is not very extensive in Dumfriesshire. 
Still there are a few places worthy of a visit of the geologist. 
The carboniferous system lies on the top of the old red sandstone 
or Devonian strata, but are known from the vast mass of vege- 
table matter which occurs in the lower members of the carboni- 
ferous system. It is to the fact that the chief quantity of the 
solid element being carbon that the system takes it name, such a 
mass which has formed beds of coal. Coal being only mineralised 
vegetation finds its entry into the mass of the bituminous or 
coal-formed shales, and gives many of the sandstones and 
limestones of this formation a carbonaceous well marked appear- 
ance. The system is generally divided into the three well-marked 
groups—the lower coal measures or carboniferous slates, the 
mountain limestone, and the millstone grit. The plants most 
characteristic of the group are—Sphenopteris affinis, bifidi, S. 
lincaris, pecopteris, hetorophyllum, newropteris loshii, calemites, 
canneformis, lepodostrobus variabilis and ornatus, lepidophyllum 
intermedium, stigmaria ficoides and stellata, with sigillaria 
pachyderma, and occulata with knorria of various species, and 
favularia. 
Lower Coal Measwres or Carboniferous Slates.—This group is 
intended to combine all alternations of strata that lie between 
the old red sandstone and the mountain limestone. In some dis- 
tricts it is not so well developed. In others it attains a thickness 
of several thousand feet. In Scotland—in Fife and the Lothians 
—it has none of the slatey character, but consists principally of 
thick bedded white sandstone, dark bituminous shales frequently 
embedding bands of ironstone, thin seams of coal, and peculiar 
