198 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



the Hardt district of the Cologne-Linz region. The woody fragments 

 in Brandenburg mines are practically all from conifers; in Sachsen, 

 the fossil wood is coniferous, belonging almost wholly to the 

 cypresses; but at Tanndorf, where the conditions are well shown, 

 Penck found Sah'inia and Trapa in the lower portions, succeeded by 

 a layer with Arundo, which is followed by normal peat with Betiila 

 and Palmacitcs. Reuss's collections from the fetid limestone roof 

 of the Haring coal show that the coal was formed at the head of an 

 estuary for, mingled with remains of marine animals, it contained 

 abundant fragmentary remains of Salix, Erica, palms and other 

 swamp plants, which, it would seem, must have been torn away from 

 the still living swamp on the shore, continuous with the buried swamp 

 which has given the Haring coal. American localities tell the same 

 story respecting the woody materials. Grand'Eury,"*^* in summing 

 up the results of his studies, asserted that in the lignite areas of 

 Tertiary age he had found as many stumps with roots and branches 

 in situ, as in Carboniferous coal basins. From their position, even 

 in the midst of rocks and limestones, it is to be presumed that the 

 in situ roots are evidence of plants growing on bottoms subject to 

 inundation. The flora shows instances of local variation, one strik- 

 ing illustration being that recorded by Heusler in the Cologne area. 



Very few observers have given detailed record of localities where 

 evidences of contemporaneous erosion are distinct. The writer has 

 made careful comparison of sections preserved in basins of con- 

 siderable magnitude and he is convinced that the variations in coal 

 and the intervening rocks are such in many areas that they can be 

 explained as due only to contemporaneous erosion. The absolute 

 proof of such erosion cannot be secured except where coal mining 

 has been well-developed — and there are few such localities in the 

 American Tertiary. European basins are small and the petty varia- 

 tions due to contemporaneous erosion are easily overlooked. Very 

 clear cases of such erosion have been reported from the interval 

 rocks of Wyoming but in no case is the extent fully revealed. Evans 

 has shown that in Washington some coal beds have suffered severely 



-*'* C. Grand'Eury, Comptcs Rendus, T. 138, 1904, pp. 666 ff., 740 fif. 



