448 HIND : CARBONIFEROUS ROCKS OF THE PENNINE SYSTEM. 
Orthoceras cinctum, 0. sulcatum, Temno- 
dieilus pentagonu.s, Solenocheilus crassi- 
venter (.?), Phillipsia Eichwaldi var. mucro- 
nata, Phillipsia sp., Gyracanthus (spine), 
Psammodus porosus. 
One post, known as the Frosterley marble, is made up of fine 
specimens of Clisiopliyllum. 
It may be remarked that the fauna of the Great or Main Lime- 
stone of Weardale is therefore identical with that of the Carboniferous 
Limestone, though containing somewhat fewer species. 
The one important fact which the study of the various sections 
of the Carboniferous rocks given above demonstrates, is the rapid 
increase of detrital sedimentary deposits and the diminution of organic 
deposit (limestone) as the beds pass northwards. 
It is found that practically no change in the nature of the deposit 
takes place between Derbyshire to Settle and the Craven district, but 
from this point northwards the change comes on rapidly. The 
nature of the change, the substitution of sediment obtained by the 
denudation of pre-existing rocks, for an organic deposit, due to living 
things, points without any equivocation to the cause of the change. 
This was tlie presence of continental land within a very short distance 
to the north of a line drawn across Scotland from the Firth of Tay to 
the Firth of Clyde. 
I believe I am correct in stating that the most northerly deposits 
of Carboniferous age in Scotland are to be seen in the Pass of Brander 
and near Innimore of Ardtornish, on the mainland of Morvern. It 
is probable that the greater part of the Highlands of Scotland were 
dry land during Carboniferous times. The products of land erosion 
are deposited out at sea by the rivers which bring them down, and 
unless affected by strong local currents are deposited over a more or 
less pear shaped area, the deposit being thicker the nearer it is to the 
actual mouth of the river. Lighter materials are carried further out 
to sea, consequently shales would be laid down somewhat further 
from land than sandstones. The elevation of the land above the sea 
and its consequent effect on the rapidity of the flow of the denuding 
streams, will also have an important influence on the area and nature 
of the deposit. 
