Plant macroremains from five boreholes in Poland were studied. Two of them (Huta OP-1
and Studzianna) from the northern margin of the Holy Cross Mountains, yielded several
taxa hi the other duce borehole s determinable fossil plants were sporadic, albeit
important. Most of the taxa from the Huta OP-1 and Studzianna borehole s are typical
of the European Early Jurassic (Hettangian and Sinemurian). Both localities, although
close to one another, show quite different taxonomic floral compositions. The Huta
OP-1 flora is fern-dominated with the presence of ginkgophytes and conifers (a new
species incertae sedis, Desmiophyllum harrisii Barbacka et Pacyna is herein proposed).
which would suggest rather wet and warm conditions. This flora is typical of the European
Province of the Euro-Sinian Region In Studzianna the Siberian elements dominate gymnosperms,
mainly Czekanowskiales, which indicate a drier and colder environment. The palaeobotanical
data correspond to the results of clay mineral studies, in particular the kaolinite/illite
ratio in the source formations. The kaolinite content confirms a decrease in temperature
and a reduction in rainfall in the late Early Hettangian and the latest Hertangian
in the area.
