268 GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 
would serve to explain the Rothwell and Oulton Gravels which 
cap the watershed between the Aire and Calder from the 175 ft. 
to the 250 ft. contour. I regard these detrital deposits, often well 
bedded and associated with fine tenacious clays, as part of the 
lateral moraine of the Airedale Glacier rearranged in the lake which 
washed the side of the glacier. 
Now, whilst I am disposed to agree with the statement that a 
lake existed here — as is indeed evidenced by the presence of the 
laminated clay — a little more explanation is needful than that given 
in the latter part of the quotation. Mere rearrangement of the material 
will not suffice to give us the successioii found at Rothwell Haigh, 
where we have coarse gravel at the base, succeeded by sands becoming 
finer towards the top, and these surmounted by laminated clay and 
capped by boulder clay. 
This series of beds represents a succession of conditions in this 
area such as might result from a glacier gradually approaching and 
creeping up the spur between the Aire and the Calder. 
There were two glaciers which have to be considered in this area : 
(1) the ice coming down Airedale ; (2) the Vale of York ice. 
Messrs. Jowett and Mufi assumed that the Rothwell gravels 
were, in fact, the morainic product of the Airedale glacier, but there is 
certain evidence on this point which w^as not in their hands. Among 
the erratics of the boulder clay, I have mentioned Carboniferous 
limestone. Professor Kendall has pointed out that some of this 
limestone is of a type only to be matched by Carboniferous limestone 
to be found in situ about Richmond, and therefore beside the track of 
the Vale of York ice. Secondly, I have found in the gravel-pit pebbles 
which certainly have a wind-polished and pitted surface, and which 
seem to have belonged to the Trias of the Vale of York. I have not 
actually found these in situ in the boulder clay, but I can conceive no 
other explanation of their presence than that they were washed out of 
the clay. Thirdly, in the laminated clay are found boulders of Magnes- 
ian limestone. There is no Magnesian limestone on the route of the 
Airedale glacier. But the escarpment of the Magnesian limestone 
tract lies a few miles to the east of Rothwell. We may imagine these 
boulders then to have been rafted by bergs of ice from the advancing 
glacier and thrown down here. 
