STUR AND JOKELY BOHEMIA. 3/ 



on the remains of a monocotyledonous leaf: a fourth, reminding one 

 of a HysteriuMy on a dicotyledonous leaf. 



Dr. Debey intends to publish similar papers on the other classes 

 represented in the Cretaceous flora*, — one of the still least known 

 of all fossil floras, although in number of species it is only inferior 

 to those of the Carboniferous, Eocene, and Miocene periods. New 

 and peculiar forms filling up systematic hiatuses have been discovered 

 in the Cretaceous strata ; and genera still living may be traced even 

 to this early epoch. A narrow connection between the Cretaceous 

 and the immediately subsequent period has been indicated by the 

 occurrence in the x\ix-la-Chapelle strata of characteristic Australian 

 plants, — a tvpe which obtains pre-eminence during the Eocene period. 



[Count M.] 



On the Geology of some Parts 0/ Bohemia. 

 By MM. Stur and Jokely. 



[Proceed. Imp. Geol. Instit. Vienna, July 1857.] 



M. Stur finds that in the environs of Tabor and Sedletz, in North- 

 western Bohemia, the prevailing rock is gneiss, of many varieties, 

 dipping beneath clay-slates, and (near Tabor) beneath granite, and 

 leaning against granite near Nachod. Micaceous strata alternate 

 more or less regularly with others containing but little of this mineral, 

 and dipping, at a low angle, northward in one part, and north- 

 westward in the other part of the district. Near Horky the gneiss 

 includes two argentiferous veins, which were worked at intervals 

 from the 13th to the 19th century, but are now abandoned. The 

 ores, extracted from a depth of 480 feet, contained 36 per cent, of 

 lead and \\ per cent, of silver. 



An amphitheatre of granitic hills surrounds the south and south- 

 western continuation of the gneiss between Nechwatitz, Neuhof, Sed- 

 letz, Neukostcletz, and Borotin. This granite is white and fine- 

 grained. In the north-western portion primary clay-slate is seen 

 dipping beneath gneiss with medium-sized grains ; this last dipping 

 beneath porphyroid granite and granitic gneiss. 



Amid the gneissic region lies the granitic massif of Tabor, to 

 which the attention of geologists was first drawn by M. Zippe. This 

 granite, passing from fine-grained to compact, is bluish-grey when 

 fresh, and becomes brown by weathering. It is characterized by 

 large thin laminae of mica, imparting to it a porphyroid aspect. 

 Between this granite and the porphyroid granite of Gistiebnitz is 

 intercalated a series of gneissic bands, with subordinate calcareous 

 and amphibolic beds. 



M. Jokely found that, in the environs of Auscha and Sandau, 

 eastward of the Elbe and Leitmeritz, in North-western Bohemia, the 

 prevalent rocks are Cretaceous and eruptive. The three subdivisions 



* See Quart. Journ. Geol. Soc. vol. vii. part 2, Miseell. p. 111. 



