PALEONTOLOGY. 281 



where 120 beds are superposed on one another, exclusive of a 

 great many which are less than a foot in thickness ; the coal 

 beds at Johnstone, in Scotland, and those in the Creuzot, in 

 Burgundy, are some of them, respectively, thirty and fifty feet 

 in thickness,* while in the forests of our temperate zones, the 

 carbon contained in the trees growing over a certain area 

 would hardly suffice, in the space of a hundred years, to cover 

 it with more than a stratum of seven French lines in thick- 

 nsss.f Near the mouth of the Mississippi, and in the " wood 

 hills" of the Siberian Polar Sea, described by Admiral Wran- 

 pel, the vast number of trunks of trees accumulated by river 

 and sea water currents affords a striking instance of the 

 enormous quantities of drift-wood which must have favored 

 the formation of carboniferous depositions in the inland waters 

 and insular bays. There can be no doubt that these beds 

 owe a considerable portion of the substances of which they 

 consist to grasses, small branching shrubs, and cryptogamic 

 plants. 



Th association of palms and Coniferae, which we have in- 

 dicated as being characteristic of the coal formations, is dis- 

 coverable throughout almost all formations to the tertiary 

 period. In the present condition of the world, these genera 



fire, but that it has more probably been produced in the moist way by 

 the action of sulphuric acid, is strikingly demonstrated by the excellent 

 observation made by GSppert (Karsten, Archiv fur Mineralogie, bd. 

 xviii., s. 530), on the conversion of a fragment of amber-tree into black 

 coaL The coal and the unaltered amber lay side by side. Regarding 

 the part which the lower forms of vegetation may have had in the for- 

 mation of coal beds, see Link, in the Abhandl. der Berliner Akademie. 

 der Witsenschaften, 1838, s. 38. 



* [The actual total thickness of the different beds in England varies 

 considerably in different districts, but appears to amount in the Lanca- 

 shire coal field to as much as 150 feet. Ansted's Ancient World, p. 

 78. For an enumeration of the thickness of coal measures in America 

 and the Old Continent, see Mantell's \Vonders of Geology, vol. ii., p. 

 69.] Tr. 



\ See the- accurate labors of Chevandier, in the Comptes Rendus de 

 F Acadimie de Sciences, 1844, t. xviii., Part i., p. 285. In comparing 

 this bed of carbon, seven lines in thickness, with beds of coal, we must 

 not omit to consider the enormous pressure to which the latter have 

 been subjected from superimposed rock, and which manifests itself iu 

 the flattened form of the stems of the trees found in these subterranean 

 regions. " The so-called wood-hill* discovered in 1806 by Sirowatskoi, 

 on the south coast of the island of New Siberia, consist, according to 

 Hedenstrftm, of horizontal strata of sandstone, alternating with bitu- 

 minous trunks of trees, forming a mound thirty fathoms in height ; at 

 the summit the stems were in a vertical position. The bed of ilrift- 

 wood is visible at five worsts' distance." See Wrangel, Reise 

 der Nordkbs'.e von Sibericn, in den Jahren 1820-24. th. i.. s. 102. 



