**3. Ice age woodland refugia in highlands between the elevations of 500–700 m ASL: Petény cave and Rejtek 1 rock shelter, Bükk Mts, NE Hungary**

Excavations starting in the 1950s as part of a collaborative work of vertebrate paleontologists, anthracologists, and archeologists in two cave systems found in the Bükk Mts in NE Hungary yielded outstanding records regarding the presence of ice age woodland refugia in a highland setting of the Carpathian Basin [45–48, 75–78]. One of the studied caves was formed in Triassic limestone at an elevation of 735 m ASL (Petény Cave) (**Figure 1**). The other, the Rejtek rock shelter, found at an elevation of 500 m ASL was formed in Jurassic limestone. Both cave systems are facing south. According to the retrieved vertebrate fauna and recovered archeology, sediment accumulation must have initiated from the terminal part of the last glacial in these karstic depressions. Fine-stratigraphic sampling of the identified lithological horizons yielded numerous charcoal pieces. The taxonomic composition of these charred plant remains indicated the emergence of mixed taiga woodland at this elevation during the last stage of the last glacial [45–48]. Besides the clear dominance of spruce and Scots pine, scattered patches of deciduous elements like elm, oak, lime, maple, beech, ash, as well as hazel were also present in these woodlands. On the basis of this information, József Stieber came up with the idea regarding the presence of ice age woodland refugia for temperate thermomesophylous trees in the Carpathian Basin for the first time [45–48]. Unfortunately, his observations were by no means welcomed by the majority of Hungarian botanists of his time. It was only in 1999 when a British-Hungarian research group managed to corroborate his presumption independently [49–52, 55, 56]. The samples taken by Stieber and his colleague Dénes Jánossy yielded numerous terrestrial mollusk shells, which were handed over for further evaluation to the late Endre Krolopp, an outstanding Quaternary malacologist of the late twentieth century. The malacological remains of both caves have been scientifically evaluated along with a revision of the charcoal remains complemented by 14C dating of the major stratigraphic units sampled in the 1950s [55, 56]. According to the results of these investigations, Central European woodland mollusk elements prevailed in this area from even the last glacial onward (**Figure 4**).

The prevailing taxon of the Late Glacial horizon is *Cochlodina cerata*. The modern distribution of this taxon's habitat is found in the area of the Northern, Northeastern Carpathian Mts ranging from the lower alpine woodlands of the foothills to the upper alpine woodlands to a height of ca. 1000 m [79–84]. Consequently, the studied region in the Bükk Mts, NE Hungary, between the elevations of 500–750 m ASL must have acted as an ice age


Holocene taxa during the Late Glacial in the Carpathian Basin as postulated earlier on the basis of paleoecological, geological, geochemical, and sedimentological observations made at the environmental historical site of Bátorliget marshland discussed in the next chapter [55]. According to our findings, rock walls and rock surfaces with a southern exposure in the inner Subcarpathian zone of the Carpathian Mts at suitable heights between 800 and 500 m ASL must have had special microclimatic conditions (angle of incoming radiation, minimal height for air humidity condensation), which allowed for the emergence of temperate woodland refugia [53–56, 67], even during the coldest periods of the ice age [91, 92]. Similar woodlands could have developed at the ecotone of floodplains and foothill areas of

Ice Age Terrestrial and Freshwater Gastropod Refugia in the Carpathian Basin, Central Europe

http://dx.doi.org/10.5772/intechopen.71910

103

**4. Ice age refugia at the interface of windblown sand dunes and floodplains: examples from the Bátorliget marshland, Nyírség region, NE Hungary, and the Ócsa marshland, Danube-Tisza** 

*rivulare*, has a clear preference for milder climatic conditions (**Figure 5**).

A similar paleoassemblage was identified in the Postglacial/Holocene deposits of the Ócsa marshland. However, in this latter profile, the Pontian *Pomatias rivulare* is substituted by

The highly protected area of the Bátorliget marshland is situated on the NE part of the Great Hungarian Plain (GHP) approximately 2 km west of the state border with Romania in the area of the Nyírség alluvial fan covered by windblown sands (**Figure 1**). The Ócsa marshland is on the other located at the NW part of the GHP at the fringe of the Danube Lowland in an area of scattered windblown sand dunes. Both sites are located in an interdune depression hosting initially an oligotrophic lake during the ice age, which developed into a calcareous lake system finally evolving into a eutrophic lake then a marshland. According to the available absolute chronology, the emergence of an oligotrophic lake initiated around 20–22 ka during the coldest period of the last glacial: the last glacial maximum (LGM). However, the first mollusk remains turn up in deposits dated to the Late Glacial only. Shells of the Pontian *Pomatias rivulare*, the Central European woodland dweller *Discus perspectivus*, as well as the Boreal woodland dweller *Discus ruderatus*, presently populating the alpine woodlands of the Carpathian Mts, turn up as early as the transitional zone between the Late Glacial and the Postglacial in the profile of the Bátorliget marshland. This paleoassemblage composed of cold-loving and thermophilous elements can be clearly synchronized by the findings of pollen analysis indicating the presence of a mixed taiga hosting stands of pine and various temperate arboreal elements [55, 95]. These records thus indicate the development of a mixed taiga woodland at the interface of windblown sand and floodplain areas in the NE part of the GHP during the ice age, whose composition was the same as the mixed taiga woodlands of the foothill areas mentioned in the previous chapter. A significant difference in the mollusk faunas is the appearance of a Pontian gastropod taxon, which evolved during the Tertiary in the Carpathian Basin [96, 97], in the marshland sequence. This gastropod taxon, the *Pomatias* 

island-like hills in the heart of the basin as well [93, 94].

**interfluve, Central Hungary**

**Figure 4.** The radiocarbon-dated palaeoecological data from Petény (Peskő II) and Rejtek rock shelters A1 = anthracologicalbased vegetation phases of the sequence in the Rejtek site, A2 = mammalian phases of the sequence in the Rejtek site, A3 = local malacological zones of the sequence in the Rejtek site, A/B = archeological finds and times in the analyzed sites, B1 = anthracological- and pollen-based vegetation phases in the Petény site, B2 = mammalian phases of the sequence in the Petény site, and B3 = local malacological zones of the sequence in the Petény site.

refugia for woodland mollusk taxa [49–55, 64]. These findings have been corroborated by later studies on the Quaternary mollusk fauna of the Hungarian Highland and the Western Carpathians [85–90]. It must be noted that in Ref. [90], radiocarbon results presented span the Holocene Epoch alone. Cold-loving and cold-resistant elements in the accessory fauna of the *Cochlodina cerata* horizon are represented by a single taxon, presently dwelling in beech and pine woodlands: *Discus ruderatus*. However, warmth-loving elements like *Bradybaena fruticum* and *Euomphalia strigella* have also been recorded in this part of the profiles. Consequently, the general composition of the mollusk fauna is clearly in line with the observations and conclusions made on the basis of charcoal remains. Namely, the presence of refugia for temperate thermophilous woodland taxa within a Late Glacial mixed taiga forest [45–52]. The Late Glacial presence of *Discus perspectivus* as well as the records of the mollusk taxa *Cochlodina cerata*, *Cochlodina laminata*, *Clausilia dubia*, *Clausilia pumila*, and *Laciniaria plicata* in the layers representing the Pleistocene/Holocene transition is a highly outstanding feature of the sites. The collective appearance of *Discus perspectivus* and *Discus ruderatus* indicates the development of a dual refugia in the study area [49], i.e., the collective presence of Pleistocene cold-resistant and cold-loving elements with warmth-loving Holocene taxa during the Late Glacial in the Carpathian Basin as postulated earlier on the basis of paleoecological, geological, geochemical, and sedimentological observations made at the environmental historical site of Bátorliget marshland discussed in the next chapter [55]. According to our findings, rock walls and rock surfaces with a southern exposure in the inner Subcarpathian zone of the Carpathian Mts at suitable heights between 800 and 500 m ASL must have had special microclimatic conditions (angle of incoming radiation, minimal height for air humidity condensation), which allowed for the emergence of temperate woodland refugia [53–56, 67], even during the coldest periods of the ice age [91, 92]. Similar woodlands could have developed at the ecotone of floodplains and foothill areas of island-like hills in the heart of the basin as well [93, 94].
