126 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



harder than the upper ones. At another place, the bed consists 

 of brown coal, 7.5 meters, clay, 0.25 meter, brown coal, 0.25 meter. 

 The lower bench is harder and better than the upper one, which is 

 crowded with stems of Sequoia langsdorffii. The roof is clay, with 

 impressions of plants. 



Von Amnion^"'' has described the Gustav mine, near Oettingen 

 a.M. in Bavaria, as yielding Moor- and Alooskohle with included 

 Lignit (bituminose Holz). This chief bed, underlying upper Plio- 

 cene clay, is from 8 to 16 meters thick and is mined in open work- 

 ings within an area of about 2,000 acres (800 ha). At Schwarzen- 

 feld, the workable coal is but 2.5 meters thick and contains not 

 far from 16 per cent, of wood. In all cases, the observer appears to 

 have been impressed profoundly by the resemblance of these deposits 

 to peat beds, both in structure and in distribution. 



Miocene Coals. — Marine conditions prevailed in the present 

 coastal plain along the Atlantic in North America during the Mio- 

 cene and conditions favoring accumulation of vegetable matter did 

 not exist in the adjacent region, for no coal has been found. But 

 the vegetation was there and swamps were on some of the streams, 

 Berry^^^ discovered the remains of a cypress swamp near Richmond, 

 Virginia, associated with the well-known diatomaceous earth of that 

 region. Among the characteristic plants are Taxodium, Nyssa, 

 Salix, Quercus and others of types familiar in modern cypress 

 swamps. The conditions for some reason were equally unfavor- 

 able elsewhere on the continent, and no coal positively identified as 

 Miocene has been found anywhere in economic quantity except 

 within a petty area in California. There,^^^ in the Monte Diablo 

 range, is the bed, which was mined long ago and for many years 

 was the chief source of fuel for steamboats. The bed, as measured 

 by Arnold, is 14 to 16 feet thick and has a dip of about 70 degrees. 

 The coal varies greatly in quality both vertically and horizontally, 

 specimens from some openings being, in composition, very much 



i"o L. V. Ammon, " Bayerische Braunkohle," etc., pp. 15-21, 26, 27. 



171 E. W. Berry, " A Miocene Cypress Swamp," Torrcya, Vol. VIII., 1909, 

 pp. 233-235. 



172 R Arnold, " Coal in the Monte Diablo Range," U. S. Geol. Survey, 

 Bull. 285, 1906, pp. 223, 224. 



