48 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



at which the floor could be studied. Vertehraria has been recog- 

 nized in underclays of Queensland; Equisetites roots are in under- 

 clays of the Vosges as also at Nice, where the plants seem to have 

 supplied material for the coal. The underclays of Lettenkohle in 

 Unterfranken are root-beds. The coals of the Richmond field, ac- 

 cording to Rogers, have nothing answering to the Stigmaria-c\a.ys 

 of the Carboniferous ; but the underclays are present. They carry 

 no Stigmaria, for the gigantic Lepidodendron and Sigillaria had 

 disappeared ; but Fontaine has shown that Schisoneiira is present 

 in the floor of the main bed. 



The flora has been studied in all of the important areas. In 

 the Upper Oolite of southern England, ferns, conifers and cycads 

 are the prevailing types ; the Lower Oolite of Yorkshire contains 

 ferns as the preeminent feature though conifers and cycads are 

 abundant ; Equisetum is common above the coal horizon, at which 

 ferns and conifers prevail. Conifers, cycads and some ferns from 

 Spitzbergen have been described by Nathorst. The Ipswich or 

 upper division of the Queensland Jura-Trias has ii species of ferns, 

 4 of cycads and one of Equisetum; ferns prevail in the lower por- 

 tion of the Lias within the Steierdorf-Anina area and cycads in the 

 upper ; but in the Fiinfkirchen area, the flora consists chiefly of 

 ferns, cycads and lycopods. Equisetum is extremely abundant in 

 the Trias of Austria and Calamites and Pterophyllum were obtained 

 at many places ; the Trias of Hungary has yielded cycads, Palissya 

 and some ferns, but collections have been small, as the coal is unim- 

 portant. The beds in the Atlantic coast areas of the United States 

 contain cycads, reeds and ferns — the last being few in species but 

 extremely abundant in individuals. 



That the coal-bearing deposits were laid down on an undulating 

 surface is well shown in the Liassic areas of Hungary. Within the 

 Torzburg area, the underlying rock is crystalline schist ; in the 

 Steierdorf area it is Dyas but in that of Fiinfkirchen it is Trias. 

 A similar condition is distinct in the Trias of Virginia and North 

 Carolina. In the Richmond field, the interval between the lowest 

 coal seam and the granite varies from a few inches to 600 feet, 

 while in the Dan River basin of North Carolina it is more than 

 1,000 feet. 



