258 
HUGHES : IXGLEBOROUGH. 
Brow through a much greater thickness. At first the material 
did not appear to be much worn by transport, but later on, 
for some reason or other, the only fragments that reached this 
spot were far travelled pieces of quartz from which all trace 
of softer sediment had been removed, and which had them- 
selves been rolled into small pebbles. 
I drew special attention to the well-established fact that 
certain parts of the pre-Carboniferoas floor must have gone 
do^^Ti earlier than others, so that lower Carboniferous beds 
than any seen on Ingleborough were deposited in other areas 
before the submergence of the sea-plain, w^hich here forms such 
a striking feature at the base of the Carboniferous conglomerate. 
When we come to examine the details we find that the Mountain 
Limestone thickens out enormously towards the Lune Valley, 
and unless repeated by undetected faults mast, near Kirkby 
Lonsdale, be twice as thick as it is on Ingleborough, while on 
the north entirely different deposits occur, wedged in under 
the equivalents of the lowest beds of Ingleborough, and inter- 
calated in the lower parts of the series, as shown by Prof. Harkness 
in his evidence before the Coal Commission.* Palaeontologists 
who are at work on these beds are making out that the character- 
istic fossils of our lowest beds of Ingleborough correlate them 
with beds well up in the series, as developed in the west and 
north, while conglomerates, which represent the shingly shore 
of the encroaching Carboniferous sea, occur at the base every- 
where, though they are of very different age. 
Dr. Vaughan calls attention to the fact that the " appear- 
ances," to use Barrande's Avord, of one species do not always 
coincide with the " appearances " of another species ; that is 
to say, that the changes of environment or other cause which 
brought about the disappearance of a particular brachiopod 
from a given area may not have acted in the same way or so 
quickly upon a group of corals. I remember Dr. Duncan urging 
at a meeting of the Geological Society the value of the sedentary 
coral for purposes of correlation of strata, and the correct- 
ness of this view has been well shown b}^ Dr. Vaughan, who 
* See also Mem. Geol. Survey Expl. Sii., 97 S.VV. old series, 102«.\V. 
old series, 30 new series. 
