3fi GEOLOGICAL STRUCTURE OF THL 



tion, are overlaid by a massive micaceous cODglomfr" 



rate, or grit rock, containing crystals of felspar like 

 porphyry, in which, besides gigantic ctdmarii,* oc- 

 cur veins of the argentine calcareous spar of Kir- 

 wan, similar to that of Cornwall, resembling silvery 

 talc or steatite, in which are occasionally imbedded 

 minute chrystals of blue and white fluor like those, 

 equally rare, in the gneiss of the Schuylkill, together 

 with common calcareous spar and chrystals of sul- 

 phate of lime. In the bituminous slate clay, which, 

 as usual, accompanies this coal, besides impressions 

 of ferns, and the supposed Equiseta, there are vesti- 

 ges of some enormous flaccid leaved gramineous 

 plant, leaves of one of the Scitaminese similar to 

 those of ginger, and fine casts of a. palm, resembling 

 the pennate fronds of some species of Zamia, or 

 Cycas. The apparent remains of fish, which alse 

 occur together in such uncommon abundance, are ex- 

 tremely ambiguous, inasmuch as the supposed fins 

 alone, are found. The coal in this formation, instead 

 of that even continuity so obvious in that of the west- 

 ern states, presents very limited beds, which, as they 

 recede or occupy the centre of the basin, vary from 

 6 or 8, to that of 40 feet in thickness ! The coal 

 itself, highly bituminous and brittle, contains abun- 

 dance of pyrites. What relation the breccias and 



* An assumed generic name for an assemblage of extinct 

 Zoophytes? (one species of which, is the Phijtolithus striatic^!- 

 »iis, of Martyn's Petrificata Derbiensia) 



