266 GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 
and also to see whether the carbonate of lime "was present as original 
fragments of limestone or calcite, or as a secondary mineral. The 
heavy minerals yielded were the following : — zircon, garnet, leucoxene, 
rutile and tourmaline, named in the order of their abundance. One or 
two very small grains may be monazite, but of this I am not sure. 
When the heavy liquid with which the separation was effected was 
reduced to sp. gr. 2 '7, it was found that a large number of the grains 
which came down were of rhombohedral form with the boundaries 
very sharply defined, and also showing zonary banding. In addition, 
masses showing a radial structure and giving a faint black cross were 
fairly numerous as well as a few groups of sharp pointed crystals which 
on closer examination with a high power objective, were seen to be 
scalenohedra of calcite. Here, then, is the explanation of the cause of 
the ef!ervescence, and a further test showed that the calcite had been 
deposited in the more porous layers which gave the effervescence in 
the tests before described. 
Below the laminated clay is sand about 15 ft. thick. It shows 
current bedding with a prevalent direction from north-west to south- 
east. The sand is noticeably coarser in the bottom part than near the 
top. 
Petrology of the Sands. 
The description already given for the sands at Woodlesford is 
applicable to these epccept that the manganiferous patches are absent, 
or nearly so, and there is a greater abundance of coaly layers. The 
material making up these sandy beds are just such as would be yielded 
by the rocks occurring in the valleys of the Rivers Aire and Calder, and 
of these the Millstone Grit has been by far the most important con- 
tributor. When the sands are treated with hydrochloric acid there is 
a slight effervescence. 
Percentages of various grades : — 
Weight of sand taken =465-0 grams. 
Stopped by 10 mesh =11-2 
30 „ = 50-3 „ 
60 „ =223-8 
90 „ =127-6 
Through 90 = 51-5 
464-4 
