On the Bitum inous Shales of Linlithgowshire, dec. 10 



Some recent physico-geographical investigations by Mr 

 Hull of the Geological Survey go to prove that speculations 

 as to such changes may have an actual foundation in fact. 

 In a paper on the position of the arenaceous and argillaceous 

 in contrast to the calcareous strata of the Carboniferous 

 system of Great Britain,* it is shown on the map accom- 

 panying Mr Hull's paper, that they are developed in opposite 

 directions ; and that while the Mountain Limestone attains 

 a development in solid mass of from 2000 to 3000 feet in 

 the Midland district of England, it becomes thinner in 

 Northumberland, and mixed with coal seams, while in Scot- 

 land it is attenuated to a thickness of only 70 feet. It will 

 suggest itself, on examining the map, whether the coal strata 

 lying above the marine limestone in Scotland, are not 

 really on the horizon of the vast limestone masses of 

 England ? The examination of several sections appears to 

 confirm this view. Mr Geikie has found in some parts of 

 the Lesmahagow district, as well as on the flanks of the 

 Cheviots, a remarkable conformity betwixt the Upper Old 

 Ked Sandstone beds and the Lower Carboniferous series. f 

 They in fact form physically only one formation, — the dis- 

 tinction drawn betwixt them on geological maps being 

 entirely arbitrary. There is a clear natural demarcation, 

 however, betwixt these beds and the Lower Old Ked Sand- 

 stones and Silurian shales, which again form only one 

 formation. A similar uniformity of the Upper Old Eed 

 Sandstone with the Lower Carboniferous series exists in 

 Ireland. A closer uniformity in physico-geographical rela- 

 tions thus exists betwixt the strata of these two countries, 

 than with those of England. 



The Scottish carboniferous strata exhibit the following 

 succession of strata in various sections : — First, Immediately 

 above the Upper Old Eed Sandstone beds, and conformable 

 with them, a series of shales and sandstones of great thick- 

 ness : these are distinguished by the Burdiehouse fresh-water 

 limestone bed, and in some places the Houston coal-seam ; 

 secondly, two or three beds of marine limestone intercalated 



* Journal of Geological Society, vol. xviii., 1862. 

 t Ibid. vol. xvi., 1860. 



