54 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



ing that all the stems are prostrate, thought them a fossil raft, re- 

 mains of an ancient pine forest, transported by a river and buried in 

 the delta sands and muds, as is the case with rafts of the Mis- 

 sissippi River. But the description of conditions leads one to hesi- 

 tate before accepting the reference to rafts. The Mississippi rafts, 

 as described in European works of Mantell's day, were not the rafts 

 as they were. It is not probable that the rafts of the Atchafalaya 

 and Red River would produce deposits such as those under con- 

 sideration. The features- are more like those observed along the 

 Athabasca and some other North American rivers, where great 

 masses of driftwood occur, the interstices being filled with silt and 

 sand. Mantell emphasizes the presence of ripple markings in the 

 Wealden ; slabs of sandstone, clay and limestone on the Isle of Wight 

 are often covered with them. Imprints of annelid and molluscan 

 trails, of crustacean claws, of pectoral fins of fish as well as of feet 

 of reptiles have been obtained. The formation is of essentially 

 fresh-water origin. Lyell,^ in describing the Lower Wealden or 

 Hastings sand, remarks that one finds at dift'erent heights in the 

 section strongly rippled slabs of sandstone. Some of the clay beds 

 had been exposed, for sun cracks are abundant. A red sandstone, 

 near Horsham, contains innumerable traces of a plant, apparently 

 Sphenoptcris, with stems and branches disposed as if they are stand- 

 ing erect on the place of growth, the sand having been deposited 

 gently around them. Similar conditions have been observed else- 

 where in this formation. 



Some coal has been found in the Wealden of France, but it is 

 of little importance. The lignites of Simerols* sufiice as illustra- 

 tion. The area is small, with radius of about 25 kilometers. The 

 section at one locality shows (i) clay, 0.90; (2) lignite, 2.50, at 

 times without partings, but at others divided into two or three 

 benches; (3) shale, 0.70; (4) lignite, friable, not mined, 1.50; (5) 

 carbonaceous shale, 0.80; (6) lignite, compact, i to 1.50; total, 7.90 

 meters. This deposit, at times only 4.60 meters thick, underlies 



2 See " Formation of Coal Beds, II.," Proc. Anicr. Phil. Soc, Vol. L., 

 1911, pp. 548-551- 



3 C. Lyell, "Elements of Geology," 6th ed., New York, 1866, pp. 350, 351. 

 *Arnauld, "Des argiles lignitiferes des Sarladais," Bm//. i'oc. G^-o/. France, 



II., Vol. 23, 1866, pp. 59-63 ; Meugy, the same, pp. 89-96. 



