8 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



not more than 60 by 200 kilometers. The only workable seam is 

 extremely variable. The greatest thickness is in the group of mines 

 known as Nuejols, where the seam is 70 to 80 centimeters. The 

 center of the area is on the summit of the plateau, where, in two 

 mines, the thickness is but 45 centimeters. The decrease continues 

 toward the north, there being only 12 to 15 centimeters at 10 

 kilometers north from La Cavalerie. The lower part of the coal 

 group is largely calcareous and the limestones have both marine and 

 freshwater forms. The coal rests directly on black shale ; the roof 

 is similar but more carbonaceous and, at times, has a wood-like 

 structure; it is at most 12 centimeters thick and is combustible. 

 The coal yields a very fair coke with imperfect metallic luster. 

 The lenticular form of the seam is distinct, for the thickness de- 

 creases in all directions from La Cavalerie. 



Austria. — The Jurassic coals of Upper Austria belong to the 

 Grestener beds at the base of the Lias. They have been described 

 by Lipold^'^ and his associates. Hertle, in his notes upon the mining 

 area of Bernreuth on the eastern side of this region, states that 

 Czjzek's profile shows a marine limestone between two coal seams, 

 which contains Mytilus, Pleuromya and Pecten, and a sandy shale 

 in the same section has Ammonites. Sphasrosiderite concretions as 

 large as half a cubic foot are fossiliferous. These calcareous de- 

 posits were not exposed at the time when Hertle made his examina- 

 tion, but he saw a sandy shale with Pholadomya and Mytilus. The 

 coal seam, which is mined, is 3 feet thick and rests on an underclay 

 containing remains of plants. The coal looks like good coal but it 

 has 42 per cent, of ash. 



Near Gresten, according to Rachoy, the coal seams are in a sand- 

 stone group. One tunnel cut seven streaks of coal, one to 12 

 inches thick, while a shaft passed through 16 seams, 3 inches to 

 3 feet thick. The roof and floor are sometimes clay and sometimes 

 sandstone. The thickest bed yielded a good caking coal with less 

 than 4 per cent, of ash ; the dip is about 20 degrees. Plant remains 

 are poorly preserved but marine fossils occur in fine condition. At 



!'■ M. V. Lipoid, G. V. Sternbach, J. Rachoy and L. Hertle, " Das Kohlen- 

 gebiet in den nordlichen Alpcn," Jahrb. k. k. Gcol. Rcichsant., Band 15, 1865, 

 pp. 29-61. 



