Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 76. (Budapest 1984)

Kordos-Szakály, M.: New data to the Miocene flora of Nógrádszakál (Hungary)

Table 4. Number of certain species (pieces) in some genera of these floras which are close to the Nógrádszakái localities and the relative frequency of their sum as compared to the total number of taxa in the different localities "~ locality Eger — Bertece Paris Buják MikóBánhorSály Balaton "— Tihamér Buják falva váti genus —Betula 1 _ 1 3 3 8 6 7 Alnus 1 — 1 5 4 11 7 14 Carpinus 1 1 I 2 3 3 3 Fagus — — 1 1 5 — 5 8 Quercus 1 3 5 4 5 7 7 29 Populus 1 3 6 2 5 6 3 8 Salix — — 3 I 1 4 1 I Ulmus 1 4 9 4 6 6 5 7 Acer 1 1 2 4 4 18 4 9 total (pieces) 7 11 30 25 35 63 41 86 (°/o) 29 32 39 46 43 78 41 47 flora at Paris stream is connected with Buják which shows a trasitional position toward the four further "classical Sarmatian" floras. These latter ones (Mikófalva, Sály, Bánhorváti, Balaton) on the basis of the number of their common species are highly similar to each other. Lacking quantitative data the chronological evolution of the investigated floras of Nógrádszakái and those of other localities can be outlined only with the aid of the qualitative evaluation of the number of flora elements. I separated the genera which occur in these floras in a very high specific number and I also carried out a review on their specific composition (Table 4). During these investigations I could take into consideration only Arcto-Tertiary trees and bushes namely the following genera: Betula, Alnus, Carpinus, Fagus, Quercus, Populus, Salix, Ulmus, Acer. As Middle and Upper Miocene are generally characterized by the rapid expansion of Arcto-Tertiary elements and by the increase of their specific number, I compared the totalled frequencies of the species of these genera which can be found at the different localities. According to the chronological order established above these values at the different localities are as follows: Eger-Tihamér 29%, Bertece 32%, Paris 39%, Buják 46%, Mikófalva 43%, Bánhorváti 78%, Sály 41%, Balaton 47%. Apart from individual differences an evolutionary trend toward an increase in the number of the most frequent Arcto-Tertiary species is clearly visible. Within a short time they even doubled. Comparing the results of the study with those of previous comparative investigations it is also observable that within this sequence three phases of flora evolution can be distinguished, represented by the remains of Eger-Tihamér, Bertece

—Paris and Buják— Mikófalva—Bánhorváti—Sály-Balaton (Fig. 6). After the establishment of the evolutionary order and relationship of the floras two methods are possible for the stratigraphical ranging of the localities. One is the conversion of the degrees of relationship, i.e. the distances from the flora of the Paris stream calculated with help of the C

sp index and given in a frequency value into years; the other one is the stratigraphical ranging given by the geological data of the localities. The starting of the first method (C

sp

) are two rough radiometric age dates for the lower and upper boundaries of the Badenian stage. The so-called "middle rhyolitic tuff" was formed 16 million years ago while the "Upper rhyolitic tuff" was formed 14 million years ago. I con-