448 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



division, aside from the Russkohle portions, are, according to 

 Mietzsch, coking. Geinitz states that the Planitz coal is of Sigillaria 

 origin, while that of the Russkohlenflotz is derived from Calamites. 



The higher zone has 7 seams of workable gas coal, 5 of which, 

 one to three meters thick and yielding a caking gas coal, are practi- 

 cally exhausted. At best, their area was insignificant. The lowest 

 two seams, Zach- and Schichtenkohlenflotz, are in larger area and 

 each has a maximum thickness of somewhat more than 5 meters. 

 Like the other seams, these divide and subdivide, the former toward 

 the west and the latter toward the east. The total thickness of Coal 

 Measures in the Erzebirge basins averages not far from 400 meters ; 

 that of the lower division, according to Mietzsch, varies from 40 

 meters in the southwestern portion to 80 and even 150 meters in the 

 northeast, owing to inlaying of sandstones and conglomerates. The 

 Rothliegende in these basins contains some worthless streaks of coal 

 in the lower part. 



The Dohlen basin or Becken des Plauenschen Grundes contains 

 workable coal of Permian age, as determined in 1849 by Geinitz and 

 Gutbier. Murchison*^ found the whole thickness of Lower and 

 Middle Rothliegende between 800 and 900 feet. The conglomerates 

 of the lower portion are gray, with blocks of granite, quartz and 

 even of Coal Measures rocks. The coals are from Permian plants. 

 These deposits, occupying a depression in Silurian rocks, consist of 

 sandstones, conglomerates and shales, with, in the northern portion, 

 a porphyry flow at the base. The color is mostly gray but varie- 

 gated shale is present in the basal portion of the Middle Rothlie- 

 gende. The coal seams are about midway in the Lower Rothlie- 

 gende, within a mass of gray shale and sandstone, 20 to 30 meters 

 thick. Geinitz mentioned four seams, of which the lower two are 

 very thin. The third occasionally is thick but, for the most part, its 

 coal is so dirty as to be almost worthless. The fourth or Hauptflotz 

 is from i to 7 meters thick, the greatest thickness, as Hausse has 

 shown, being in the deeper part of the basin ; toward the border it 

 becomes thin and impure. The partings are thin, but some of them 

 are remarkably persistent. The coal is mostly laminated, but it 

 often passes into Brandschiefer. The ash content is high, being, 



43 R. I. Murchison, " Siluria," 3d ed., 1859, P- 345- 



