384 PEOCEEDINGS OF THE GEOLOGICAL SOCIETT. [May 8, 



Wherever two large valleys join, there is a great pile of drift 

 heajied np in the angle between them, on the gable end of the 

 bounding hills. This is seen at the junction of Wharfe- and Litton- 

 dales — again at Kettlewell, at the junction with the main valley of 

 a large gill descending from Coverhead, and in other places — also 

 above West Burton, on the gable end between Walden and Bishop- 

 dale. This points unmistakably to glaciers descending the two 

 valleys, and throwing down together their inner lateral moraines. 

 Moreover, the rock is apt to be moutonnee where the pressure of a 

 glacier would be greatest. One case, in particular, I can mention : 

 just above the hamlet of Kilnsey is a conspicuous scar of solid lime- 

 stone ; the northern face of this rock is beaiitifnlly smoothed ; and 

 this is just where the Wharfedale glacier would press that coming 

 down Littondale against the side of the valley. We should doubtless 

 see more polished and scratched surfaces, were it not that lime- 

 stone, when not covered with clay, yields so rapidly to the action of 

 the weather ; but we do sometimes find scratches and grooves, and 

 they are always along the valleys. There is an excellent example, 

 for instance, of grooved and polished limestone preserved under a bed 

 of clay near Kettlewell. 



Another general phenomenon is the following. Where a barrier 

 of rock crosses a valley, the drift is piled up in mounds against 

 and over the rock, as if deposited by a glacier against a barrier ; and 

 above such a barrier there is generally a wide spread of alluvium, as 

 if a lake lying in a rock-basin had been silted iip. This is nearly, 

 if not quite, universal. 



Again, where we have such a spread of alluvium, we do not see 

 the solid rock in the bed of the stream between the two ends of the 

 alluvium ; when we do get the rock in the stream, it is near the be- 

 ginning or the end of the alluvium, and there, too, a mound of drift 

 crosses the valley. This, again, points to rock-basins and local 

 glaciers depositing a terminal moraine against the rock barrier. It 

 is a difficult matter jxisitively to prove the existence of a rock-basin ; 

 but Avhen, over and over again, we find a spread of alluvium above 

 a rock barrier, and that no solid rock shows in the course of the 

 stream through the alluvial flat, save at its ends, the beds all the 

 while retaining their usual dip, this amounts by a cumulative argu- 

 ment nearly to a proof thereof. 



A great deal of the drift is as angular as ordinary moraine-matter 

 might be expected to be ; but a great deal of it is also composed of 

 rounded pebbles, well scratched ; and yet these two cannot be sepa- 

 rated from one another ; and the rounded and scratched drift has 

 often the characteristic shape of moraine, whether terminal or lateral. 

 But rocks riding on the surface of a glacier, and shed therefrom, will 

 be neither rounded nor scratched. The latter kind of drift, then, 

 did not so come. But rocks sticking in the bottom of a glacier will 

 be both rounded and scratched, and the more so the further they 

 have travelled. So we must consider many of our moraines to have 

 been shed from the body of the glacier. It struck me, too, that the 

 further we go from the parent hills, the more generally rounded and 



