476 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



lying shale, 3 meters thick. Sandstone overlies the shale and it fills 

 the Catamites to their roots, which are in the coal. Sigillarks are 

 sometimes vertical to the stratification. Stigmaria characterizes the 

 mur and sometimes is found in the roof. 



BoLilay^^ states that in the roof of mine Veine Christiane within 

 the Concession of Bully-Grenay, in Pas-de-Calais, he saw great erect 

 trunks of Sigillaria, 30 to 60 centimeters in diameter. The species 

 was not determinable, but the roots are unquestionably Stigmaria 

 abbreviata. This seam is higher in the section than the Ste.-Barbe 

 of Dourges. Bertrand^'' examined two erect stems in a mine within 

 the Lens Concession of Pas-de-Calais. One, in roof of the Veine 

 Desire and not absolutely vertical, has its base resting on a coaly 

 film; underneath the veinule is abundance of Stigmaria rootlets and 

 a great Stigmaria rhizome was seen ; but this could not be traced as 

 a slip had occurred at the horizon of the veinule, so that no proof 

 could be obtained that this Lepidodendron stump is in its original 

 place. The other stump, a Sigillaria, was in roof of a seam, 14 

 meters above Desire ; the broadened base rests directly on the seam 

 and its roots cannot be traced; if it be in situ, the roots would be 

 unrecognizable, as they wiuld have been changed into coal. The 

 stump directly above Desire is cut ofif at base as though sawed. This 

 is a common condition, observed in other coal areas. 



Barrois^" discussed the matter generally in connection with de- 

 scription of vertical stems at many horizons in the Lens and Lievin 

 Concessions within Pas-de-Calais. The existence of such trees had 

 been known for a long time and they had been regarded usually as 

 being in the place of growth ; but latterly some geologists have main- 

 tained that they had been transported, A recent discovery of erect 

 trees in the roof of the Veine Leonard of Lievin seems to confirm 

 the later explanation. He presents a diagram, drawn carefully to a 

 scale, which shows the relations. The trees are parallel, are envel- 



"^"^ L'Abbe Boulay, " Recherches de palaeontologie vegetale," etc., Soc. 

 Sclent. Bruxelles, 4me annee, 1880, p. 32. 



''■9 P. Bertrand, " Note sur des arbres, debout a la fosse No. 3 des mines 

 de Noeux," Ann. Soc. Geol. Nord, t. :i7, 1908, pp. 50,51. 



s° C. Barrios, " Note sur la repartition des arbres debout dans le ter- 

 rain houiller de Lens et de Lievin," Ann. Soc. Geol. du Nord, t. 40, 191 1, 

 p:\ 187-196. 



