GENERAL VIEWS. 
187 
unusual agitations of the sea, and would then assume the stratiform 
structure, most remarkably where the deposit was least thick, and the 
contrary. 
The argillaceous members of the mountain limestone series, though 
equally void of any indications of violent currents, show proof in their 
universal fine lamination, and minutely sandy texture, of the influence 
of some long continued and widely diffused watery movements. 
The gritstones of the mountain limestone formation appear to have 
been aggregated under the influence of a continual deposition of car- 
bonate of lime; for they all contain more or less of this earth very 
finely disseminated among the grains of sand which compose the mass. 
They are usually harder, and less argillaceous, than the sandstones of the 
coal measures above millstone grit, and contain much less felspar. Such 
of them as contain an unusual quantity of carbonate of lime and argilla- 
ceous matter, disseminated among the grains of quartz, as in Penyghent 
and under Richmond castle, become very hard and cherty and these 
contain organic remains. The flagstones are always very micaceous and 
often carbonaceous, and associated with thin argillaceous partings. What 
are called gray beds, and girdles, have the same general characters. The 
siliceous grains of these rocks are fragments, not crystals ; the mica is 
also in fragmentary scales ; the plants occasionally found are broken ; 
and the general tendency of all the evidence points clearly to variable 
watery currents from the land, excited at a considerable distance, and 
moderated by passing through great breadths of the ocean. 
This view is strongly confirmed by the fact that the prevalence of 
coal seams in the Yoredale series and lower limestone is almost in the 
direct ratio of the abundance of gritstones in the section. While in 
all the great shales of Ireland, Derbyshire, Bolland, and Craven, hardly 
the least trace of coal is to be found, it occurs in almost every part of 
the Yoredale series from Wen sley dale to the Tweed. 
The general distinctness of the argillaceous and arenaceous bands, in 
those districts where they alternate, implies alternate influence of dif- 
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