262 GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 
dark brown laminae appear to be very fine grained with a few grains 
of quartz and mica. The mica is variable in quantity, being most 
abundant when the brown lamina is thickest. The quartz grains are 
exceedingly small and angular. The light brown laminae are much 
more open in texture and usually somewhat coarser than the dark 
laminae. One milky looking grain looked very like a piece of calcite 
with rhombohedral outline, and when a drop of hydrochloric acid was 
placed upon it a brisk effervescence took place, showing that the 
diagnosis had been correct. Following this up by testing other grains, 
it was found that calcite was present in some quantity in all the light 
brown layers. If a piece of the laminated clay be taken and a smooth 
face prepared perpendicular to the laminations, and then a brush dipped 
in hydrochloi'ic acid be drawn across the laminations each light brown 
lamina effervesces briskly while each dark lamina is unacted upon. 
Further reference to this fact will be made in the Appendix, where 
other laminated clays are also described. 
It was also found that each bed of clay had its laminations com- 
pletely destroyed by penetrating rootlets in certain layers, and in 
many cases a cast of the hole caused by a rootlet which had decayed 
had been made in calcite. Some of these were separated and examined, 
and found to be hollow in each case while the branching of the minute 
rootlets had been perfectly preserved. When dissolved in dilute 
hydrochloric acid, only a slight deposit remained showing them to be 
almost pure calcite, with only a YeTy slight admixture of clayey material. 
This destruction of the lamina? by penetrating rootlets is interesting 
in the light it throws upon the absence of bedding shown by true 
under-clays of the Coal Measures. An excellent demonstation of the 
fact that the rootlets had actually destroyed the laminae was afforded 
at Rothwell Haigh. The washings from sand had been allowed to 
settle in a pool, where they formed a laminated clay. Upon the 
dried surface of clay, clumps of grass were found growing, and on 
digging these up it was seen that the clay penetrated by the fibrous 
rootlets of the grass was without laminations, though laminations were 
distinct where there had been no growth of vegetation. 
Scattered through the laminated clay, especially in the top bed 
at Woodlesford were concretions of practically pure carbonate of lime 
of very irregular shape, reminding one of the " race " in the Thames 
Valley brick earths. A careful search was made m the clays for traces 
