GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 
261 
the base of the top bed of clay maintained a constant horizon the top 
of the lower bed of clay, which was exposed at the end of the excavation, 
was undulating and, of course, the sand and gravel separating the beds 
increased in thickness where the lower bed of clay was thinner. This 
would point to contemporaneous erosion of the lower clay by a stream 
which shifted its course. 
The most striking character of the clays was the fine lamination 
which they showed when the spades of the workmen made a clean 
Photo: A. Gilligan] [X 15. 
Photomicrograph of the 
Upper Laminated Clay of Woodlesford. 
vertical cut. The alternating layers were light brown and dark 
brown in colour. The number of laminse varied fi'om 90 to 130 to thr 
inch so far as they can be counted with a binocular mineralogicai 
microscope, but observations upon dried specimens of the clay show 
that manj^ of the laminae which had been counted as one split up into 
two, so that the number given above would have to be increased. The 
