GOODCHILD : GLACIAL PHENOMENA OF UPPER RIBBLESDALE. 245 
immediately after it had reached its climax.* This could hardly have 
been at a period much, if any, more remote than ten or twelve 
thousand years from our own time. As it melted, and the unwonted 
load was gradually eased off the earth’s crust, this began to rise 
towards its former elevation. That, I take it, explains how some of 
the raised beaches were formed. Of any other submergence there is 
no valid evidence, as I showed in 1874. Furthermore, the whole of 
the sediment, stones, sand, and mud included within the ice 
{I cannot believe that any appreciable quantity was gathered 
underneath it, as used to be thought) was gradually liberated as the 
ice melted ; so that the whole of the rock surface covered by the ice 
received a Coalitig of drift eae in thickness to that of the 
ice from which it was derive many localities this liberation of 
stones and mud went on ney oie the water resulting from the 
liquefaction of the ice always taking the nearest line of low ground 
on its way back to the sea. But the conditions under which the 
melting took place must have varied much from time to time, and 
this was more especially the case at some distance from the line of 
watershed. Consequently, much of the finest detrital matter was 
washed out and transported to levels lower still, and the water-worn 
residue was left behind as beds of sand and gravel, which, as the 
conditions changed once more, gave place to boulder clay. This will 
Serve to explain how it happens that, at Ribblehead, for example, 
water-sorted material is interstratified with the boulder clay, as it 
generally is elsewhere. It also explains why it is that the axes of the 
drift mounds ee or quite, coincide with the prevailing lines of 
movement of the ice. There were pre-existing rock mounds there, 
which had been shape by long glacial erosion, and when the stony 
and muddy ice melted over these rock mounds the glacial sediments 
gtadually enveloped the mounds and moulded themselves to the 
form of their rocky core, in much the same manner as the surface of 
a growing field of wheat follows the ups and downs of the field in 
which it was sown. I think it will be found, in the majority of 
Cases, that every drumlin has a rocky core, and that the shape 
of the drumlin, in a general way, conforms to that of the rock 
it envelops. 
It should be noted here that, as stones were melted out of the 
ice, they were, occasionally, transported in directions different from 
* T have repeatedly emphasized this sera during the last eighteen years, 
and more especially so in a general can my views on glacial phenomena, 
Published under the title of ‘Ice Work in Eadenside,’ Trans, Cumb. and West. 
*» No. xi, (1887), pp. tego of which several hundred copies were 
distributed amongst glacialists, British and Foreign. 
August 1852. 
