SECTION OF TREUILLE MINE. 



analogous to that of the tropics, a fact which is in conformity 

 with what has already been explained. 



171. The coal deposits are everywhere attended with similar 

 results. Entire trees are found, some of which are standing 

 upright with their roots penetrating the stratum below them, 

 exactly as they penetrated the soil on which they grew. Several 

 examples of these have been presented in England, one of the 

 most remarkable of which occurred in the construction of the 

 railway between Manchester and Bolton. Near Dixonfold five 

 large stems of Sigillarise were found erect with their roots striking 

 into layers of clay below. They stood upon the same level one 

 beside the other, the trunks being surrounded and filled by soft 

 blue shale, and the carbonised bark being all that remained of the 

 original structure. All these trunks seemed to have been broken 

 violently off at a point four or five feet above the roots, no 

 traces of the upper parts of the trees being discovered. 



172. On the coast of Northumberland, within a space of half a 



Fig. 87. Section of the Treuille Mine at St. Etienne. 



mile in length, twenty upright trees were discovered by Mr. 

 Trevelyan, and similar ones were found in the same coal-field at 

 some distance, as if they had been the continuation of a sub- 

 merged forest like that of the Isle of Portland. 



In the Newcastle coal-field a stratum of sandstone occurs 



125 



