m 



' 01 » the j! 



"^ which 



It 

 ut at 



I 



was : 



or 1; 



.. 



Records 



Jukes.) 



th e nianni' 



itres 



rica, ai 



in va: 



nid 



[OllO 



fvato 



Coal ^ 



3 



of Y^ 



1p valu e ' 



111 n ° In 



111 



w# 



•oal lS ' 



FOBMATION OF COAL. 



59 



?r Posed 



1, rather ; slstm S of beds of mineralized vegetable matter. These are 



interstratified with beds of sandstone, shale, and ironstone. 



bedded rock, and, in its purer states, may be defined as con- Upper 



- ~ . -__ * fjAT.T.T?TV 



Gallery. 



Wall-case 41 . 



South Wales 



boniferous limestone underneath the Coal measures is there, 



where thickest, about 2000 feet thick ; the overlying Coal 



ii to i ■ measures about 12,000. In this there are about 100 beds 



lUh!!?' of coal, of varying thickness ; and underneath each bed of 



coal is the underclay, (usually fire clay,) containing Stigma- 

 rice. (See specimens 148, 149, and 151 ; also Coal-measure 



Beds of 

 into the« 



at hand sp- cases in the JLower Gallery, Nos. 44 to 54). This underclay 

 •right «oaii was the terrestrial soil on which the plants grew that 

 lore than! formed the coal, and the coal itself is the mineralized vege- 

 -mall beds £ tation formed partly by the decay of the Sigillarice, of which 

 e sandstone Stigmaria were the roots.* It is not unlikely that after 

 loss, somett an early stage the decaying vegetable matter that went to 

 3, but as t f° rni coa l> in some respects resembled peat moss, which, 



in a humid and equable climate, accumulated with consi- 

 derable rapidity. 



The strata that lie between the beds of coal frequently con- 

 tain numerous impressions of ferns, catamites, trees allied to 

 hjcopodiums, and other vegetable remains. Other strata con- 



Productas. 



) 



Witho 



it is therefore evident that these interstratifications of coal, 

 with other strata, indicate alternations of terrestrial and sub- 

 aqueous conditions, and the lowest bed of coal in the South 

 Wales coal field being about 1 2,000 feet below the highest bed 

 of these Coal Measures, the whole mass of stratified deposita 

 must have been formed during a period of average slow 

 depression of the area, varied by pauses, during which part 



William 



stantly present in the Welch underclays, and he connected this circum- 

 stance with the occurrence of the overlying coal. Mr. Einney of 

 Manchester, first proved Stigmarice to he roots of Sigillarice 



