hughes: ingleborough. 135 
When we come to examine the basement deposits of the 
Mountain Limestone in detail we find many other curious facts 
that require explanation. For instance, we find that where the 
troughs or valleys in the old sea bottom are considerable, the 
deposit that fills them is generally red, but the conglomerate or 
sandstones that occur above the level of the depression or extends 
anywhere over the general surface of the older rocks is never red. 
This is first of all a question for the chemist. Where we 
now find beds containing carbonate of lime in red rocks, as in 
the cornstones of the old red sandstone, or evidence that there 
has been carbonate of lime present though now dissolved away, 
as in the lenticular beds full of casts of fossils in the rusty red 
Tertiary beds of Kent, these subordinate beds are green. 
Therefore we should not expect to find red beds in the main 
mass of the Mountain Limestone, except the red earthy residuum 
due to late action of surface waters. 
It seems not improbable that in the case before us the 
oxidized superficial deposits of the adjoining pre-Carboniferous 
land, when they were swept down and preserved at once in a 
valley or trough, some of which were perhaps sub-aerial, retained 
their red colour, but that when the material had long been 
washed in the surf of the encroaching sea, all the little pellicles 
of red oxide which coated the grains of sand were removed, and 
the whole mass lost its colouring matter. 
Most of the carbonate of lime was probably derived from 
organisms which grew on the spot, but the other sediment seems 
to have come from far and to have been well rolled and washed, 
as may be inferred from the constant recurrence of bands of 
quartz pebbles in the lower part of the Mountain Limestone, as 
well seen near Thornton Force, for instance. They had tra^'elled 
so far that all the softer sedimentary or other rock in which the 
quartz veins occurred had been ground down to sand and mud, 
and only the quartz, rolled into small, perfectly smooth pebbles, 
survived the long journey. The various forms of life so abundant 
in the overlying limestone had not yet migrated into this area ; 
therefore fossils are rare in the red debris swept into the hollows. 
