121 



Mr. Hali; and I cannot but anticipate that the close study of the 

 palaeozoic fossils of America and of Russia, which have found their 

 way into our museum within the last two years, will lead to results 

 highly interesting to the naturalist, by showing variations of the same 

 species when found in very distant localities ; and most important to 

 the great principles of geological classification, which, when rightly 

 understood, can onlj^ be based upon the admission of such variations 

 in widely remote contemporaneous deposits. 



In presiding over the Section of geologists at the Manchester, 

 Meeting of the British Association, when this memoir was first in- 

 troduced to the notice of my associates, I ventui'ed to commend it 

 for its truthfulness of research and practical value, and I was happy 

 to find, that it was received in a similar spirit by this Society, the 

 members of which will doubtless take a still deeper interest in it 

 when they know that its author received his geological and chemical 

 education in University College under the tuition of our lamented 

 secretary, Dr. Turner. 



Theory of the Origin of Coal. — American and European Evi- 

 dences 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 

 Jicoides and fireclay ; and we have now before us the result of the la- 

 bours of our associate Mr. Logan in the coal-fields of Pennsylvania 

 and Nova Scotia, in examining which his chief object seems to have 

 been to ascei'tain 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 ^^ngland. 



Availing himself of the prior researches of the American geolo- 

 gist, Professor PI. Rogers and his assistant surveyors, who had pre- 

 pared 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 convolu- 

 tions. Since that time the Governor and legislature of the Canadas 

 have wisely selected 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 ef- 

 fective 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 with the already described feature 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 fireclay or argillaceous materials filled with Stigmaria 

 Jicoides, 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 aiFording 250 tons daily, 

 Mr. Logan states he had also detected the Stigmaria Jicoides in similar 

 underclay. With such extended observation spread out before 

 them, the evidences in which all seem to point one way, young geo- 

 logists may well be led to suppose that the theory which, if I may so 



VOL. JV. PART I. K 



