14 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



wholly resembling roots. At another, he discovered a rhizome with 

 its rootlets, which made the relations of the other markings clear. 

 *' Through such horizontal rhizomes, the analogy of the Mesozoic 

 underclay with the Carboniferous Stigmaria-beds and the recent or 

 sub-recent reed beds is the more marked." Roots are rarely recog- 

 nizable in freshly exposed rock but they are sufficiently distinct 

 after slight weathering. Gothan removed the debris for some 

 meters at several horizons and in one day he found well-marked 

 underclays with roots, associated with 8 coal seams. In all, he un- 

 covered such clays under 12 seams. 



Spitahergen. — Nathorst-- has described a sandstone group mid- 

 way in his Jurassic of Spitzbergen. It contains coal seams and 

 freshwater mollusks. A coal seam is exposed on the south side of 

 Cape Bohemian, underlying sandstone and resting on shale or shaly 

 sandstone. Leaves abound above the coal. Ginkgo, Baiera, with 

 cycads and some ferns, and Elatides is under the coal. Bituminous 

 sandstone with plant impressions and a seam of coal was seen at 

 another locality, where, somewhat higher in the section, there is a 

 soft clean sandstone with the same plants as well as freshwater 

 mollusks, Lioplax and Unio ; but still higher is a deposit with fossil 

 wood and marine mollusks. The same group was seen on the shore 

 of Van Keulen Bay, where the lower portion contains some thin coal 

 seams and some clay ironstone. 



Siberia. — Coal seams of Mesozoic age are present in extensive 

 areas within Siberia. Their place in the column had not been de- 

 termined when the description cited was prepared.-^ They were 

 taken to be Jurassic, but they may be in part Rhaetic. 



In the region between the Yenisei and Irkutsk rivers, the coal- 

 bearing portion of the Jura, 60 to 90 meters thick, consists essen- 

 tially of sandstone with subordinate beds of conglomerate and shaly 

 clay. Fat and dry coals are here and boghead is not rare. A small 

 area, about 10 kilometers square, of the freshwater Jura, near 



22 A. G. Nathorst, " Beitriige zur Geologic der Biiren-Insel, Spitzbergens, 

 und des Konig-Karl-Landes," Bull. Geol. Inst. Upsala, Vol. X., 1910, pp. 362, 

 363, 365-369. 



23 " Apergu des explorations geologiques et minieres le long du Transsi- 

 berien," publie par le Comite Geologique de Russia, 1900, pp. 68, 86-92, 97, 

 179, 182, 190, 197, 199. 



