GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 265 
These are usually of Carboniferous limestone or fine grained 
sandstone. Below the boulder clay is found a bed of finely laminated 
clay, and this calls for further description. The bed is best seen on the 
south side of the gravel pit. Indeed, it is hardly seen properly on the 
north side as the laminations have been almost completely destroyed, 
for it is not there capped by boulder clay. It is redder in colour than 
that found at Woodlesford, and contains fewer laminse, but it is in such 
a crumpled condition — no doubt as a consequence of its being over-ridden 
by the ice which deposited the boulder clay — that it is difficult to count 
the laminae. Towards the bottom the clay is much bluer, as is usually, 
of course, the case, as a consequence of the oxidation of the upper part. 
At the eastern end of the section the boulder clay cuts out the laminated 
clay and rests directly upon the sand. As recorded previously,* blocks 
of Magnesian Limestone are found embedded in this laminated clay. 
The largest seen in situ — which yielded Aximis and Turbo — was 
about 1 ft. X 10 in. x 7 in., but the largest seen in the pit and evidently 
derived from the clay, as some was found adhering to it, was 2 ft. 4 in. 
X 1 ft. 4 in. X 1 ft. 2 in., and was a hard crystalline mass with well- 
marked bedding. A peculiarity is observable in the distribution 
of these Magnesian limestone masses and pebbles. They are 
fairly common in the lower part of the laminated clay, but 
most common about the middle just at the junction of the blue 
lower and brown upper clay. No Magnesian limestone has 
so far been found in the boulder clay, nor in the sands 
and gravels below the laminated clay, unless some of the chert pebbles 
have been derived from such a source. In the Memoir on the Yorkshire 
Coalfield (p. 779), chalk is recorded among the pebbles occurring in 
the drift at Whinmoor, and some of the masses found at Rothwell 
Haigh are as white as the chalk, but a microscopical and chemical 
examination of one such piece proved it to be a magnesian limestone 
containing practically no iron or manganese. The mistake could also 
be forgiven anyone who imagined some of the chert pebbles to be flints 
derived from the chalk, but I am of opinion after comparing them with 
chert from the Magnesian limestone that that is their source. 
Irregular concretions of carbonate of lime occur as in the laminated 
clays of Woodlesford, and the action of hydrochloric acid on the different 
laminae is the same. Some of this clay was tested for heavy minerals, 
* Trans, Lezds Geol. Assoc., pt. XYI., p. 31. 
