TRANSACTIONS OF SECTION C. 1037 
wards across the submerged platform of which Shetland and Orkney are the surviv- 
ing relics. 
11. Recent Advances in West Lothian Geology. 
By H. M. Cavett, B.Sc. 
Until after the discovery of the oil shales about twenty-five years ago, the rela- 
tions of the Lower Carbonilerous rocks of West Lothian were very imperfectly under- 
stood. Nothing of importance has been written on the geology of the eastern part 
ef the county since 1861, when the Explanatory Memoir accompanying the 
Geological Survey map of the district was published. Since then much new 
evidence relating to the upper part of the Calciferous Sandstone series has 
accumulated. 
The Calciferous Sandstone or Lower Carboniferous series, as developed along 
the great anticline of Midlothian, consists at the base of a series of red sandstones 
with thin shales and marls, and occasional interbedded volcanic rocks at the top. 
Above the red rocks come the white and gray sandstones of Granton and Craig- 
leith, which are in turn overlain by the black shales of Wardie, and the sandstones 
and shales of Hailes and Redhall. Each of these two great divisions has, 
according to the measurements of Mr. John Henderson, a thickness of over 
3,000 feet. 
The oil shale group, which comes next, includes the ‘Cement stone group,’ 
apparently begins with the Pumpherston shale, situated some 780 feet below the 
Burdiehouse limestone. It occupies the remainder of the Calciferous Sandstone 
series and has in West Lothian a thickness of about 3.100 feet, so that the whole 
thickness of Lower Carboniferous rocks in West Lothian probably exceeds 9,000 
feet. The Dunnet shale is the lowest member of the upper group of oil shales, and 
lies about 400 feet above the Burdiehouse or Camps limestone. About 450 feet 
higher up comes the Broxburn shale, which is perhaps the most important of the 
West Lothian oil shales. The strata intervening between the Dunnet and Pum- 
pherston shales, and including the limestone, are chiefly argillaceous shales with 
thin calcareous bands and occasional sandstones. Above the Dunnet shale they 
become more arenaceous, and thick sandstone beds are developed, one of which has 
long been quarried at Binny, near Uphall, for building and ornamental purposes. 
The Broxburn shale, which is several fathoms above the Binny sandstone, forms 
a well-marked horizon, as it underlies a group of marls and thin limestone bands 
varying in thickness from 80 to 270 feet. This calcareous zone, locally known as 
the ‘Broxburn Marl,’ passes under the Fells shale, above which comes another 
series of sandstone beds about 240 feet thick, which underlie the Houston coal. 
This is perhaps the oldest coal seam in Britain, as in the Broxburn district it is 
situated about 1,000 feet below the base of the Carboniferous Limestone series. 
The Houston coal is covered by about 200 feet of pale green and red amorphous 
marl, sometimes containing pieces of volcanic ash, and is apparently a fine volcanic 
mudstone. A thin coal seam and some oil shale occur just aboye the ‘ Houston 
marl,’ and two other oil shales have been worked still higher up, the highest of 
which—the Raeburn’s shale—is some 400 feet below the Carboniferous limestone. 
The oil shales and underlying parts of the Calciferous Sandstone series have 
no regular strike, but are bent about into troughs, domes, and anticlines, and are 
dislocated by large faults, besides which there is great irregularity in the thickness 
and character of the rocks, so that to work out the geological structure of the 
ground without the aid of mining information would be an impossible task. 
The oil shales are simply fine clay shales impregnated with hydrocarbon, and 
when distilled yield on an average 30 gallons of crude oil per ton, and enough 
‘ammonia to yield from 10 to 45 lbs. ammonia sulphate. They have evidently been 
deposited extremely slowly in a large gradually-subsiding estuarine or fresh water 
area, inhabited by numerous fishes, lamellibranchs, and small crustaceans, whose 
remains, along with those of plants, were constantly being deposited on the sea 
1 Communicated by permission of the Director-General of the Geological Survey. 
