1038 REPORT—1885. 
floor along with a comparatively small proportion of muddy sediment. Oil shale is 
easily recognised in the field by its resistance tothe disintegrating action of the 
weather, and by the facility with which it can be cut and curled up with the point 
of a knife. 
The Carboniferous Limestone series, whose thickness is about 2,000 feet, is 
divisible into three main groups: a basal group with sandstone shales, thin limestones, 
and one coal seam at the bottom; a central group with coal seams and no lime- 
stones; and an upper group with three limestones, sandstones, and a few thin coal 
seams. At Bo'ness, on the Firth of Forth, north of Linlithgow, the coal-bearing 
group has a thickness of about 900 feet, and is subdivided by a central zone of 
interbedded basalt rocks 530 feet in thickness, into an upper and a lower series, 
each containing four workable seams of coal and a seam of ironstone. 
The oldest member of the interesting volcanic series of West Lothian seems to 
be a bed of tuff resting on the Houston coal near Queensferry, from the denudation 
of which the Houston marl here situated a few fathoms higher up, may have been 
derived. Volcanic activity was rife during almost the whole of the Carboniferous 
limestone period, especially in the district south of Linlithgow, where the great 
bank of interbedded basalt rocks forming the Bathgate and Torphichen Hills was 
poured forth. These old lavas extend from beneath the lowest marine limestone 
in almost uninterrupted succession to near the top of the limestone series, and have 
a total thickness of more than 2,000 feet. On each side the volcanic rocks thin 
out and become replaced by sedimentary strata and coal seams in the Bo'ness and 
Bathgate coalfields. ‘Necks’ of diabase and basalt tuff, piercing the lower parts 
of the Carboniferous Limestone and the Calciferous Sandstone strata to the east of 
Linlithgow are numerous, and have probably been connected with interbedded rocks 
on higher horizons now removed by denudation. The largest, forming the Tor Hill at 
Keclesmachan, has a major diameter of about 600 yards, and cuts through the 
Houston coal and underlying shales. 
12. Barium Sulphate as a Cementing Material in Sandstone. 
By Professor Frank Crowes, D.Sc. 
Bischof mentions instances of foreign sandstones in which the material which 
cements the sand grains together is barium sulphate; but it appears that up to the 
present time no such sandstone has been discovered in the United Kingdom. 
Having learned from my colleague, Professor Blake, that opinions of geologists 
differ regarding the calcareous nature of certain sandstone beds in the neighbourhood 
of Nottingham, I undertook to ascertain the chemical composition of this sand- 
stone. At the spot in question the sandstone appears as two conical hills known as 
Stapleford and Bramcote Hills, and as a pillar of rock about twenty feet in height 
known as the Hemlock Stone. The Hemlock Stone stands in the space intervening 
between the hills,and is capped so as to be somewhat mushroom shaped. In 
company with Professor Blake I procured specimens of the sandstone at different 
levels of the hills and of the stone. One of the specimens was subjected to careful 
chemical analysis by two senior students in my laboratory at the University College, 
Nottingham; they find the very high amount of 30 per cent. of barium sulphate in 
the sandstone, I have also recently detected the presence of much barium sulphate 
in all the sandstone specimens from both the hills and the Hemlock Stone, while 
some of the lower beds also contain calcium carbonate. The percentage proportion 
of barium sulphate present in the samples is at present being determined with care. 
The results of the chemical examination of this sandstone thus far show that 
geologists who took samples from the lower part of the Hemlock Stone would 
consider the sandstone to be calcareous after applying the usual acid test, whilst 
others who examined the cap of the stone would find no calcareous matter, and. 
would fail to detect the barium sulphate which is the true cementing material. It 
seems probable that the protective cap of the pillar owes its comparative permanence 
against weathering action to the presence of this almost insoluble sulphate in large 
proportions, 
