Prof. T. Rupert Jones — Address. 565 



probably in a warm (perhaps sub-tropical ') climate, to account for the hundreds of 

 square miles of continuous coal-seams. 



Much has been learnt from the broken and rotting ruins of a forest, standing on 

 an area of the coal-growth, having been here and there sealed up and preserved in 

 that original state, before hydrocarbonisation had proceeded far ; whilst the rest of 

 the fallen timber and accumulated relics passed into the state of bright coal, and 

 became almost undistinguishable as to its structure except under the microscope after 

 special manipulation. The ' coal-balls ' of Oldham, in Lancashire, and the ' bullions ' 

 at South Owram, in Yorkshire, are calcareo-carbonaceous nodules, having been 

 formed by the infiltration of water- carrying carbonate of lime from the shells in 

 an overlying shale down into the bed of woody fragments and other bits of dead 

 plants. The carbonate of lime there segregated from the mass to certain centres, 

 and preserved, in round nodules, the vegetable structures, before they were quite 

 decomposed, more or less distinct as they had fallen on the forest floor. Hooker, 

 Binney. Williamson, and others have elucidated much of the botany of the coal 

 from this source. 



In the Lower Carboniferous series at Pettycur Bay, Burntisland, in the Firth of 

 Forth, are some well-preserved relics of the materials which would otherwise have 

 been used to form a coal-seam (referred to by Williamson and Binney). In this 

 case volcanic material has been ejected into or through a peaty mass, and, having 

 removed by force some of the soft wet material, has been mixed up with it and 

 settled down as a hard stratum, with well-preserved fragments of wood and other 

 tissues, into which carbonate of lime was subsequently infiltered (Carruthers). 



A third instance was discovered by Mr. Wiinsch, in 1865, in the Lower Car- 

 boniferous series on the north-eastern shore of the Isle of Arran, where numerous 

 plant-remains are well preserved in and under volcanic ashes. The strata are 

 alternate sandy shales, thin coal-seams, and peperino-like tuff. Numerous truncated 

 trees remain upright, rooted in the shale. Sigillaria, Lepidodendron, Lepidophloios, 

 and Halonia, besides Sphenopteris and other ferns, are present.^ 



Cannel, etc. — Under the name of ' cannel ' are known some important varieties 

 of coal, useful for distillation and gas-making ; and certainly they differed in their 

 method of deposition both from ordinary coal and in some particulars among them- 

 selves. They all appear to have been formed of vegetable matter that, having 

 been soaked and macerated to a black pulp, like the most rotten and semi-fluid 

 peat, in lakes, lagoons, or other limited water-areas, became homogeneous masses 

 of hydrocarbon, with much still discernible vegetable tissue, and occasionally with 

 bones, teeth, and scales of fishes, and remains of Amphibia. Earthy matter was 

 sometimes mixed with the cannel ; and occasionally so much accumulated that 

 the black mud graduated into carbonaceous shale. Light substances would also 

 have been blown into the water by wind. According to the relative abundance of 

 j'ellow-reddish hydrocarbons and macrospores, or of amorphous black substance 

 (cnrbon) and microspores, is the difference between black and brown cannel 

 (Carpenter). 



Elsewhere the condition and place of the cannel are such as to suggest that, like 

 a burst peat-bog of the present day (Buckland), the fluid carbonaceous pulp escaped 

 from its birthplace, and found local hollows at lower levels that could receive and 

 keep it. It is also suggested that such black, decomposed, fluid refuse of a swampy 

 jnngle, bordering a lagoon, might drain into the water, and settle as carbonaceous 

 mud, or as coal itself, among the water-plants there ( Grand' Enry). If poured in 

 suddenly, it probably overwhelmed and poisoned many fishes. "The cannel coals, 

 being wholly subaqueous, have not formed and do not possess mineral charcoal" 

 (Dawson) 



Torbanite consists almost entirely of minute sub-globular accretions of hydro- 

 carbon (amber- coloured by transmitted light), derived either from chemical change 

 of plant-remains, or more probably, directly from lycopodiaceous spores. 



apore-coal. — Very much of the substance of some coal-beds consists of lycopo- 

 diaceous spores that have been traced to the great lycopods, Lepidud«ndrmi and 

 Sigillaria, allied to the club-mosses and Selaginellm, and were probably shed 

 periodically in enormous quantities (Prestwich and Morris, Hooker, Binney, 



' A great predominance of ferns and lycopods indicates moisture, equability of 

 temperature, and freedom from frost, rather than intense heat (Lyell). 

 ^ Geol. Mag. 1865, and Trans. Geol. Soc. Glasgow, 1882. 



