20 Proceedings of the Royal Physical Society. 



with coal-seams ; and, thirdly, the coal strata proper, which 

 some hold contemporaneous with the English Coal Measures. 

 In some places the marine limestones are 70 or 80 feet thick, 

 but generally their thickness only averages a few feet. 



In some districts the first group of strata is absent, and 

 the marine limestone rests on the Upper Old Eed Sandstone 

 beds. The first two groups contain all the bituminous shales 

 we are about to describe. 



The Leaven Seat Shale. — One of the uppermost of the 

 marine beds has for several years been worked at Leaven 

 Seat, near Longridge. It is capped by a thick bed of shale, 

 a foot and a-half of which yields, on distillation, so much 

 paraffin as to render it of commercial value. The limestone 

 has been traced throughout the uplands of Lanarkshire into 

 Renfrewshire, and this bituminous shale has been found 

 richly developed above it in various parts of its course, 

 particularly we believe near Castlecary. 



There are two interesting mineralogical characteristics 

 of this shale. In many places its passage from the sub- 

 jacent limestone may be traced. At its junction with the 

 limestone, it has most of the petralogical characters of the 

 latter rock ; but as the bed thickens it gradually assumes a 

 clay base. The same features are likewise distinctive of 

 the shale below this in geological position, about to be de- 

 scribed. The prevalence of fish scales in the shale itself, 

 as well as the abundance of shells and corals in the lime- 

 stone immediately below it, indicate that it probably owes 

 its bituminous character to an animal origin. 



Mid-Colder Shale. — The area of the series we have enu- 

 merated as the lowest member of the Scottish group, extends 

 in segmental fashion from the Bathgate Hills to Fifeshire, 

 and thence across the Forth at Kirkcaldy, to Gilmerton and 

 Carlops. A well-known fresh-water limestone, extensively 

 worked at Burdiehouse, is knowm to extend throughout this 

 area. A shale capping this limestone is in some parts of 

 Linlithgowshire so richly bituminous as to have been mined 

 for trie purposes of distillation. Chemical works, with this 

 view, have been erected at Mid-Calder and Broxburn ; and a 

 careful observation of this shale in other quarters shows that 



