On the Bituminous Shales of Linlithgowshire, dc. 23 



cano. The Leaven Seat limestone is found immediately above 

 these beds; and as it abounds in marine fossils, another 

 change of land and sea must have ensued at its formation. 

 The whole strata were once more elevated by the great fault 

 forming the boundary of the Torbanehill mineral basin. 

 And if the Craigs and Shotts Hills were of contemporaneous 

 age with the Bathgate range, we may easily trace the shores 

 of the lake in which this very peculiar mineral substance 

 was formed ; and we will likewise be led to the conclusion 

 that it was separated by physical barriers from the upper 

 Coal Measures of the Clyde Basin. The contemporaneous 

 character of the traps found to the eastward of the range, 

 both in Edinburgh and Linlithgowshire, has been ably 

 proved by the labours of Mr Geikie and others. 



It is surely in nowise very hypothetical to assume, that 

 some relation exists betwixt the intense diffusion of trap, 

 and the extensive prevalence of bitumen in the district. 

 Bitumen oozes from the trap rocks of Winchburgh ; it occurs 

 in circular blots in the Binny sandstone, and permeates the 

 overlying limestone shales of Mid-Calder and Broxburn. 

 Now, we know of two methods by which this substance is 

 eliminated in nature. First, It appears when we confine 

 organic matter in a close vessel, and when in the absence 

 of the oxygen of the atmosphere, the carbon and hydrogen 

 unite to form its various compounds. Secondly, It is ejected 

 as an oily fluid from mud volcanos. Mr G. Walls, in an 

 able paper on the geology of Trinidad, remarks : — " The phe- 

 nomena of salses, or mud volcanos, consisting of the solution 

 of inflammable gas, accompanied by the discharge of a muddy 

 fluid and asphaltic oil, is perhaps closely related to the activity 

 first described, as carburetted hydrogen may be disengaged 

 in the direct formation of asphalt. Several of them occur in 

 Trinidad, also in the newer Parian formation."* I am in- 

 clined to ascribe the bitumen of the Balbairdie household 

 and gas coals, — and in bituminous coals generally, — to the 

 first method of forming bitumen. Again, I think that the 

 structural character of the district fairly justifies our ascrib- 



* Geological Journal, vol. xvi., 1860. 



