GEOLOGY 
for, although they undoubtedly represent a vast interval of time, the 
physical conditions under which they were formed varied but little from 
first to last. The evidence seems to show that there was still a great 
continental area to the north-west, from which rivers continued, as in 
former times, to transport the spoils of the land towards the south-east. 
But at no time throughout a period which must have been one of enor- 
mous length, did the land ever subside to an extent sufficient to admit of 
the deep sea. Sand and mud, and occasional beds of fine gravel, were 
gradually transported seaward, chiefly at the bottom of the rivers ; depo- 
sition nearly all the time being regulated by the subsidence. During 
those periods when a greater depression took place, very little mud found 
its way seaward, except such as was for a time held in suspension in the 
water, and which thereafter gently subsided to the bottom, usually in 
thin layers. In the deeper-water phases almost the only deposit laid 
down consisted of the finer remains of land vegetation, which, after 
drifting seawards, eventually became water-logged and quietly sank 
to the sea floor, there to form the materials out of which in time the 
chemical action set up by the sulphate of lime in the sea water gave 
rise to the hydrocarbon compounds which eventually consolidated as 
coal. 
Pretty pictures, relating to Carboniferous times in Cumberland, 
have often been drawn, in which the primeval forests, from whose 
remains coal has been formed, have been represented as flourishing 
on old hills, whose remains are now supposed to be left in the Lake 
district. One would fain believe that these works of art were 
founded upon well-observed facts; but, unfortunately, that is not 
the case. Woodlands there were, it is true, and we can easily con- 
ceive what both their broader features and their minor details must 
have been like; but both the growing trees and the land upon 
which they are supposed to have arisen had no place anywhere near 
Cumberland. 
A small patch of true Coal Measures, let down by a powerful fault, 
occurs in the upper part of the basin of the Eden at Argill, near Stain- 
moor. Small as the outlier is, it suffices to show that Coal Measures 
once extended over a much larger area, and were more fully developed, 
than had been supposed previous to the discovery of this outlier by the 
present writer in 1872. This outlier probably represents the only patch 
of true Coal Measures occurring anywhere in Britain to the north of 
Lancashire. 
Coal seams, throughout the whole of the Carboniferous Rocks, set in 
one after another from above downwards, as the rocks are followed from 
south to north, and thick coals of good quality occur on various plat- 
forms in different parts. It is usual, and is, perhaps, advisable also, to 
designate any strata that yield coals of economic value ‘ Coal Measures.’ 
Both the lowest beds of the Upper Carboniferous Rocks and the upper 
beds of the Lower Carboniferous yield valuable coal seams in Cumber- 
land, It would prevent much confusion if this well-known fact were 
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