GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 269 
These facts convince me that the glacier in question was the Vale 
of York ice. Now, if this ice-front reached the spur between the Aire 
and Calder it must have obstructed whatever drainage of water ac- 
companied the glacier in Airedale. At the earliest stage these Airedale 
waters would throw down their coarsest detritus as soon as they 
entered Lake Humber — which they would do just at this spot at 
Rothwell. But as the ice -front became higher and higher on the 
Aire-Calder spur, the Aire waters would be obstructed and the lower 
part of the Aire valley formed into a lake. The coarser detritus would 
be thrown down by the waters immediately they reached this lake, 
and, though it cannot be demonstrated with certainty, it may very well 
be that the deposit at Newlay, which is of exactly the same type as 
that at Rothwell, but at a height of about 200-250 ft., belongs to this 
stage. But as the confluence of the Aire waters with the Airedale 
lake advanced farther and farther away up the valley, the sediments 
reaching Rothwell would become finer and finer, until at length the ice- 
tront itself covered the spot and brought the boulder clay. 
Relative Age of the Deposits at Rothwell Haigh 
and woodlesford. 
After what has been said above it need hardly be stated that a 
great interval of time must be represented between the period when 
the Rothwell gravels and clays were formed and that at which those at 
Woodlesford were deposited. The first was an early phase and the 
latter a somewhat late phase of the Glacial period. Indeed there is 
every evidence that as the glaciers retreated up the Pennine Valleys 
the great rush of melt waters would scour off the material laid down in 
deltas and as moraines upon the slopes of the valleys and spurs of the 
hills to redistribute it in the low ground, and especially to carry the 
fine material forward into Lake Humber, where it now forms the warp 
of the Vale of York. 
Examination of Various Laminated Clays. 
With a view to throwing a little more light upon these widely 
spread clays I have examined a number from various parts of Yorkshire 
and Lancashire and, by the kindness of Prof. Leverett, from North 
America also. 
I find that they are all of the same general character, being com- 
posed of light and dark layers. The light layers invariably yield an 
