48 On the Terrestrial Arrangements connected with 



Ages ago, when by far the greater portion of vegetables was 

 converted into dead matter for the formation of coal, there was 

 but little left for the food of molluscous and other small animals. 

 The converse appears to have taken place in a later period. 

 The red and variegated sandstone formations, and the groups 

 of oolites, where those monstrous reptiles are still found in a 

 fossil state, is indeed productive of coal, but the beds are very 

 thin and few in number. On the other hand, the remains of 

 animals are copiously disseminated throughout the whole mass 

 of the rocks just mentioned. These remains, the result of de- 

 cayed animal and vegetable substances, and of very common 

 occurrence in the various kinds of sandstone, are all comprised 

 under the term Bitumen. Accordingly, we read in geological 

 works of bituminous slate, of bituminous limestone, &c. In 

 the copper slate, which is a formation very widely distributed, 

 and where the working of mines proves to be a lucrative busi- 

 ness — as, for example, at Stadzbergen, in the province of West- 

 phalia — ^the bitumen amounts to the tenth part of the weight. 

 This slate abounds with the impressions of fish, from the sub- 

 stance of which the bitumen has for the most part been de- 

 rived. The contorted position frequently indicated by these 

 impressions intimates a violent and sudden death of the animal ; 

 and their complete preservation proves, that, soon after death, 

 the fish were imbedded in a mass of finely divided mud. 



In a similar manner, the colouring principle of the most 

 esteemed species of marble, embracing the spotted and striped 

 varieties, as also those of a yellow, red, brown, or blackish 

 colour, consist exclusively of bitumen. Hence it happens that 

 all these species burn completely white — the bitumen is de- 

 stroyed, and the white limestone remains. The drawing slate 

 (black chalk) used by artists is likewise indebted to bitumen 

 for the blackness of its colour. 



The manner in which animal substances are transformed into 

 bitumen is very plainly illustrated by the ammonites — a genus of 

 shell abounding in the lias formation. Among the vast number 

 of ammonites' found in the lias, we have had occasion to examine 

 several where the large external chamber forming the abode of the 

 animal is found half empty. The creature in its death-struggle 

 seems to have, as far as possible, retreated into this part of the 



