Theory of the Origm of Coal 117 



the Permian deposits must be viewed as the fourth or upper- 

 most stage of the Palaeozoic series, notwithstanding the occur- 

 rence of Thecodont Saurians. 



2. Theory of the origin of Coal. American and European 

 Evidences compared. — At the last Anniversary we were 

 aware, from the independent evidence of Mr Lyell, that both 

 the bituminous and anthracitic coals of Pennsylvania were 

 underlaid by Stigmaria ficoidcs2^Vi^ fire-clay; and we have now 

 before us the result of the labours of our associate Mr Logan 

 in the coal-fields of Pennsylvania and Nova Scotia, in examin- 

 ing which, his chief object seems to have been to ascertain 

 whether the facts relating to the theory of the origin of coal, 

 as seen in North America, were analogous to those to which 

 he has so successfully directed attention in England. 



Availing himself of the prior researches of the American 

 geologist. Professor H. Rogers, and his assistant surveyors, 

 who had prepared the valuable map of Pennsylvania above 

 alluded to, Mr Logan has laid before us a very clear sketch 

 of the general relations of the Pennsylvanian carbonaceous 

 deposits, and of their chief convolutions. Since that time 

 the Governor and legislature of the Canadas have wisely se- 

 lected this well-trained field-geologist to execute a mineral 

 survey of the whole province ; and I am happy to acquaint 

 you that he has already commenced his task in a very effect- 

 ive and vigorous manner, by laying down as the base-lines 

 of his work, some of the great anticlinals and synclinals of 

 that region, and by connecting them w^ith the already de- 

 scribed features of the United States. In comparing the coal- 

 field of Pennsylvania with those of South Wales, with which 

 he is familiar, Mr Logan states, that he almost invariably 

 detected beneath each anthracitic coal-seam, a bed of fire-clay 

 or argillaceous materials filled with Stigmaria ficoides. In 

 his description of the coal-fields of Nova Scotia, which have 

 not yet been fully developed, but among which we hear of one 

 bed of clear coal twenty-four feet thick, and afibrding 250 

 tons daily, Mr Logan states he had also detected the Stig- 

 m aria ficoides in similar underclay. With such extended ob- 

 servation spread out before them, the evidences in which aU 

 seem to point one way, young geologists may well be led to 

 suppose that the theory which, if I may so speak, has recently 



