STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 439 



sandstones and clay shales, has some seams which occasionally at- 

 tain workable thickness. Coal seems to be confined to the lower 

 portion which is made up of mostly dark clay shale; the middle 

 division is chiefly red sandstone but contains some dark shale, yield- 

 ing plants ; the upper division, red sandstone and micaceous shale, 

 contains Walchia, Taeniopteris, Pterophyllmn, Callipteris and other 

 genera. The Zagradia district has no available coal. 



The Szekul Valley is west from Resicza. The Coal Measures 

 are exposed in a small area, where they rest on gneiss and underlie 

 the Rothliegende. The boundary between Upper Carboniferous 

 and Rothliegende cannot be determined as the passage from one to 

 the other is exceedingly gradual, lithologically, and there is no uncon- 

 formity. Four seams of coal are in the Coal Measures with maxi- 

 mum thickness of 0.75, 2, 1.50 and 1.30 meter, but the variations in 

 thickness are so abrupt that, in each case, the coal is available in 

 very Hmited spaces. The dip is not far from 45°, but changes in 

 thickness are due in small degree to the disturbance. Partings are 

 numerous ; those of the third seam are blackband, which at times 

 replaces the coal — in one mine this condition continued for 200 

 meters. The coal is very tender, barely 10 per cent, of lump coal 

 being obtained. It yields a remarkably good coke ; the ash is from 

 7 to 16 per cent., but washing removes about half of it. It is no 

 longer necessary to resort to washing, as mixing the dust coal of 

 Szekul with that from the Liassic coal of Doman gives a coke with- 

 out excessive ash. 



Bohemia. 



Coal has been found in a number of more or less widely sepa- 

 rated areas within western Bohemia as well as in one within the 

 southern portion. The general succession throughout is so nearly 

 the same, that many students in later days conceive that the western 

 areas are merely fragments of a once continuous field, intimately 

 related to the Saxony basins at the north, and that there may have 

 been a connection with the Silesian areas at the east. As Dannen- 

 berg has said, they are all limnic, as appears from the irregularity 

 of the deposits, including the coal seams, which thicken and thin, 

 often wedge out and abruptly change in character; the coal seams, 



