144 
than at present — the abnnclance of limestone boulders and 
pebbles in the lower part of the course of the river Worth, 
for instance, where the river could only have brought down 
grit or sandstone. Dr. Milligan and Mr. Bottomley have 
satisfied me that at least one of three specimens of Gryphma, 
found by them at Keighley, was obtained from the blue clay, 
and they believed that the other two had come out of the 
blue clay or overlying drift. If, as seems possible, these 
fossils were floated by ice from the north-east of Yorkshire, 
they must have come in a direction very difierent from that in 
in which the river Aire flows, and from no point of the com- 
pass could they have been brought by that river. The so- 
called gravels of the West Riding valleys often rise more 
than 100 feet above the river channels (as at Bingley, where, 
from the surface downwards, they contain numerous boulders 
up to five feet in diameter, placed at all angles, and often 
striated), and there they are of the same nature as gravels 
found remote from rivers, at greater elevations, while at both 
high and low levels they graduate into the yellowish-brown 
boulder clay which rises to the summits' of the moors. But 
an attentive examination of the sections will be sufficient, 
without any further remarks, to show that the gravels de- 
scribed in this paper are quite distinct from river gravels. 
7. Limestone Blocks resting on Millstone- grit. — I have 
found small boulders of limestone in drift resting on mill- 
stone-grit up to about 900 feet above the sea, above Slippery 
Ford, near Keighley; and I have been informed that lime- 
stone boulders have been dug out of pits on the south and 
south-west side of Bombald's Moor at nearly the same height; 
but I have to thank Mr. Yarley, C.E., of Skipton, for pointing 
out to me the existence of two large blocks, with smaller 
fragments of limestone, under a clifi", and resting on a plat- 
form of millstone- grit, at the south-west corner of Embsay 
Moor, at a height of about 1,100 feet above the present sea- 
