Prof. T. Rupert Jones — Afldrefs. 610 



measures, and of the natural history of the coal itself. To the perservering 

 energy and accurate observation of Sir William E. Logan and Sir Henry 

 T. De la Beche South Wales gave up the secrets of coal-growth, strength- 

 ening some earlier supjDositions, correcting others, and establishing a firm 

 basis for the theory that the coal has, for by far the most part, been 

 formed of plants growing where the coal now lies, although some local 

 varieties have arisen from the occasional driftage of floating timber and 

 herbage, and of long-continued maceration of vegetable matter in lakes 

 and pools elsewhere. 



Mr. (afterwards Sir) W. E. Logan, having for several years worked on 

 the geology of South Wales, in 1837 gave his maps and information to the 

 enthusiastic promoter of the Geological Survey of the British Islands, Mr. 

 (afterwards Sir) H. T. De la Beche, for public use in the construction of 

 the Survey Map and in developing the structure of the country. The first 

 volume of the "Memoirs of the Geological Survey," 1846, contains at 

 p. 145, Sir H. T. De la Beche's acknowledgment of Sir (then Mr.) W. E. 

 Logan's gift of the valuable results of his investigations in the Coal- 

 measures and discovery of the nature and meaning of the frequent 

 underclays, an account of which Mr. Logan had already published in the 

 "Annual Report of the Royal Institution of South Wales" for 1839 ; in 

 the " Proceedings of the Geological Society of London," vol. iii. February, 

 1840, p. 276, and March, 1842, p. 707, etc., and " Transactions of the 

 Geological Society," second series, vol. vi. 1842, p. 491, etc. 



The hypotheses of the formation of coal offered by earlier writers are 

 carefully reviewed in De la Beche's elaborate memoir ; and the growth of 

 opinion as to coal having been made by plants growing in place is traced 

 from De Luc (1793), Lindley and Hutton (1833 and 1835), Adolphe 

 Brongniart (1838), to W. E. Logan, by whom, indeed, it was fully established 

 before 1837. Opinions as to the nature of the Stigmaria ficoides, so 

 abundant in the ' underclays,' are also referred to ; and that it is really 

 the root of Sigillaria is accepted on tlie good authority of Brongniart and 

 Binney (p. 150). Dr. Buekland's summary (in his Anniversary Addresses 

 to the Geological Society 1840 and 1841) ' of what had been advanced by 

 British geologists in the elucidation of the Coal-measures and their natural 

 history comprised mainly the observations made by Ansted, Hawkshaw, 

 Barber, Beaumont, J. E. Bowman, and particularly W. E. Logan. He 

 stated in his Address of 1840 that " some of the vegetables which formed 

 our beds of coal grew on the identical banks of sand and silt and mud 

 wliich, being now indurated to stone and shale, form the strata that 

 accompany the coal ; whilst other portions of these plants have been 

 drilted to various distances from the swamps, savannahs, and forests that 

 gave them birth, particularly those that are dispersed through the sand- 

 stones, or mixed with fishes in the shale beds." 



Dr. Buekland's summary in 1841 is given by De la Beche ^ "as express- 

 ing his opinion that the Stigmaria ficoides [which was at that time still 

 regarded by many as an individual floating plant], growing in ponds or 

 lagoons in the localities where we now discover its remains, by mixture 

 with mud or silts disseminated among them, formed the underbeds, upon 

 which also grew the plants which now form the coal-beds, these latter, by 

 subsidence being covered by sand or mud, forming sandstone or shale, 

 between the coal strata, successive coal-beds being formed as the necessary 

 conditions arose." Sir (then Mr.) C. Lyell's important additions to the 

 subject, then lately given in his " Travels in North America," two vols., 

 1845, quoted and applied by De la Beche, were subsequently enlarged in 

 his " Second Visit," etc., two vols., 1849, and in his " Elements of Geology," 

 edition 1851, and subsequently. 



1 Prnceed. Geol. Soc. vol. iii. pp. 229 and 487. 

 * Mem. Geol. fciurvey, vol. i. Ib46, p. 152. 



