STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 129 



tense coloration. On the pure coal basis, the upper benches contain 

 almost 10 per cent, more volatile than that from the lowest bench. 



The Sutarbrandur of Iceland was described briefly by Jardin.^'^ 

 Robert had supposed that these deposits consisted merely of drift- 

 wood, but Jardin recognized that the quantity is too great to admit 

 of that explanation. The beds are numerous, having been seen on 

 all coasts except the southern ; they are horizontal and their thick- 

 ness is from mere films to 12 meters. The material is sometimes 

 compact and free from inorganic admixture, at others, it is frag- 

 mentary, mingled with pebbles and dirt while at others still it is 

 almost pulverulent. When compact it consists of alternating dull 

 and bright laminae. IMouchet's study with the microscope showed 

 that this coal is derived chiefly from conifers. 



Geikie^"^ states that in the Faeroe Islands coal of Miocene age 

 is associated with dark carbonaceous clays and is more or less len- 

 ticular. The formation is 10 to 15 feet thick on the island of 

 Suderoe, where he observed two types of coal; one is bright, with 

 glassy fracture, not soiling the fingers and not unlike some of the 

 Scotch parrot coals ; the other is dull, lusterless, soils the fingers 

 and shows vegetable structure. These alternate in the seams but the 

 dull slaty coal is more abundant than the other. Johnstrup, cited 

 by Geikie, held that every lens of glance represents a flattened stem, 

 in which annual rings can be seen. Geikie found this not true of the 

 thinner streaks and threads. The glance coal has 12 to 14 per cent, 

 of water and only 2.5 per cent, of ash ; whereas the better quality of 

 the slaty coal has 11 to 17 per cent, of water and 10 per cent, of ash. 

 The conditions resemble those in the Scottish coal fields, which led 

 Geikie to suggest that the coals are due to gradual accumulation of 

 different plants or of different parts of the same plants. 



Fournet^^*' saw at Sonnaz near Bourget in France a coal bed with 

 this structure: Lignite, 1.30 m. ; clay, 0.30 m. ; lignite, o.io m. ; clay, 

 0.05 m. ; lignite with Planorbis, 4 m. 



1"^ E. Jardin, " Note sur le Sutarbrandur d'lslande," Bull. Soc. Geol. 

 France, II., Vol. 23, 1866, pp. 456-459. 



i"^J. Geikie, "On the Geology of the Faeroe Islands," Trans. Roy. Soc. 

 Edinb., Vol. XXX., 1882, pp. 227-230, 240, 267. 



i^^J. Fournet, "Note sur les lignites tertiaires de-la Tour-du-Pin (Isere)," 

 Bull. Soc. Geol. France, II., Vol. XL, 1854, pp. 763-772. 



