488 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



united and at a short distance beyond the union they disappear. 

 The lower seam, 60 centimeters thick, yields a friable coal. Its miir 

 is a tender shale, which breaks down into a whitish clay. The sev- 

 enth system has three non-persistent seams and the eighth has but 

 one ; these are all thin. 



Some sandstones in the fourth have many impressions of Cala- 

 mites and the conglomerate at base contains many large, flattened 

 fragments of stems. Those of the fifth have great abundance of 

 Calaniites, as well as of trunks of "palms," which are vertical to the 

 stratification and are replaced with sandstone. Occasionally the 

 shales in this system as well as those associated with coal in the 

 eighth, contain impressions of leaves. 



The coal is maigre with not more than 13 per cent, of volatile. 



Spain. 



Barrois^^ devotes 82 pages of his work on the northwestern part 

 of Spain to the Carboniferous of the Asturias. He recognizes three 

 assises : Assise de Lena, consisting of sandstones, conglomerate, 

 shales, marine limestones and thin layers of coals ; this he regards 

 as equivalent to the Culm of Lower Carboniferous. Assise de 

 Sama, equivalent to the terrain houiller moyen of Nord, France, as 

 determined by Grand'Eury and Zeiller after study of the plants. 

 The rocks are sandstones, some persistent conglomerates, rare lime- 

 stones and numerous seams of coal. Assise de Tineo, equivalent to 

 the terrain houiller superieur of France, composed of shales, sand- 

 stones, some conglomerates with pebbles of Coal Measures rocks, 

 and a large number of coal seams. There are no marine limestones. 

 This is not conformable to the preceding deposits and in some areas 

 it rests on the older formations. 



Whether or not any representative of Permian exists in the re- 

 gion is uncertain. An earlier student was inclined' to assign certain 

 deposits to it, but Barrois thinks that, most probably, they belong 

 to the Lower Carboniferous. The region has been subjected to vio- 

 lent disturbance, faults and overturned anticlines are numerous, so 



89 C. Barrois, " Recherches sur les terrains anciens des Asturies et de la 

 Galice," Mem. Soc. Gcol. Nord, Lille, 1882, t. 2, No. i. Citations are from 

 pages 519-600. 



