The most recent, mainly explosive eruptions of Ciomadul, the youngest volcano in the Carpatho-Pannonian Region, have been constrained by detailed field volcanological studies, major element pumice glass geochemistry, luminescence and radiocarbon dating, and a critical evaluation of available geochronological data. These investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of Ciomadul's twin craters (St. Ana and Mohoş) that received tephra deposition during the last eruptions of the volcano. Our analysis shows that significant explosive activity, collectively called EPPA (Early Phreatomagmatic and Plinian Activity), started at Ciomadul in or around the present- and organic matter from lacustrine sediments recovered from both craters, the last of these phreatomagmatic eruptions-that draped the landscape toward the east and southeast of the volcano-occurred at ~29.6 ka BP, some 2,000 years later than the previously suggested last eruption of Ciomadul.

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Biokovo Mt is part of the Outer Dinarides, in a coastal position with a NW-SE main tectonic orientation. The highest peak called Sveti [Sv.] Jure (1762 m) towers above a karst plateau of 1300-1400 m mean elevation. Both of the long margins of Biokovo are characterized by steep and high relief energy rockwalls formed along tectonic fault lines. The plateau is intensely karstified with diverse karren forms, large dolines and several shaft caves. Its unique karstmorphological features are the relatively deep dolines with steep walls, so the landscape is characterized mainly by the sharp interdoline ridges and pyramidal peaks instead of negative doline forms. Based on the previous observation, the Biokovo plateau can be considered a "polygonal karst".The geomorphological map of a study area from this plateau has been elaborated, based on field observations and topographical maps. After digitizing the contour lines, we have created the digital elevation model (DEM) of the study area and carried out sophisticated doline-morphometrical analysis using the DEM. The most important and unique feature of the landscape, the polygonal structure, has been derived from the DEM using GIS hydrologic modelling tools.Key words: doline, polygonal karst, morphometrical analysis, Biokovo Mt. Morfometrijska analiza ponikava i krških reljefnih oblika Biokova (Hrvatska) temeljena na digitalnoj analizi reljefa i terenskom istraživanjuPlanina Biokovo nalazi se na obali Jadranskog mora i dio je Vanjskih Dinarida s tipičnim dinarskim smjerom pružanja SZ-JI. Najviši vrh Biokova Sv. Jure (1762 m) izdiže se iznad krške zaravni koja se nalazi na visini od 1300 do 1400 m. Sjeveroistočna i jugozapadna padina Biokova nastale su duž glavnih rasjeda, vrlo su strme i velike su reljefne energije. Krška zaravan građena je od jurskih i krednih vapnenaca i dolomita te je intenzivno okršena. To se očituje u bogatstvu krških reljefnih oblika: škrapa, vrlo velikih ponikava i jama. Posebnost su krškog reljefa Biokova duboke ponikve vrlo strmih padina, tako da je krajobraz istraživanog područja više obilježen oštrim i uskim grebenima i visokim piramidalnim vrhovima koji međusobno odjeljuju ponikve nego udubljenjima. Na temelju dosadašnjih istraživanja biokovsku kršku zaravan možemo smatrati "poligonalnim kršem". Na osnovi terenskoga kartiranja i različitih analiza topografse karte načinjena je geomorfološka karta istraživanog područja površine od 3 km 2 koje se nalazi jugozapadno od vrha Sv. Jure. Na temelju digitaliziranih izohipsa izrađen je digitalni model reljefa (DEM) istraživanog područja, koji je poslužio sofisticiranoj morfometrijskoj analizi ponikava. Poligonalna struktura dobivena je iz digitalnog modela reljefa uz pomoć GIS hidroloških alata.Ključne riječi: ponikve, poligonalni krš, morfometrijska analiza, Biokovo * isti rad je tiskan na mađarskom jeziku 2005. godine u KARSZTFEJLŐDÉS X. Szombathely, 2005. pp. 229-243.

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The advantage of lidar digital terrain models in doline morphometry compared to topographic map based datasets-Aggtelek karst (Hungary) as an example Doline morphometry has always been in the focus of karst geomorphological research. Recently, digital terrain model (DTM) based methods became widespread in the study of dolines. Today, LiDAR datasets provide high resolution DTMs, and automated doline recognition algorithms have been developed. In this paper, we test different datasets and a doline recognition algorithm using Aggtelek Karst (NE-Hungary) dolines as a case example. Three datasets are compared: "TOPO" dolines delineated by the classical outermost closed contour method using 1:10,000 scale topographic maps, "KRIG" dolines derived automatically from the DTM created by kriging interpolation from the digitized contours of the same topographic maps, and finally "LiDAR" dolines derived automatically from a DTM created from LiDAR data. First, we analyzed the sensitivity of the automatic method to the "depth limit" parameter, which is the threshold, below which closed depressions are considered as "errors" and are filled. In the actual case, given the typical doline size of the area and the resolution of the DTMs, we found Povzetek UDK 551.435.82:528.8.044.6(439) Tamás Telbisz, Tamás Látos, Márton Deák, Balázs Székely, Zsófia Koma & Tibor Standovár: Prednost lidarskega digitalnega modela reliefa za raziskavo morfometrije vrtač v primerjavi s podatkovno bazo topografskih kart − primer Agteleškega krasa (Madžarska) Morfometrija vrtač je bila vedno v središču kraških geomorfoloških raziskav. V zadnjem času so pri raziskavah vrtač postale zelo razširjene metode, ki temeljijo na digitalnem modelu reliefa (DMR). Lidarski podatki zagotavljajo visoko ločljivostne DMR-je, razviti so bili avtomatski algoritmi za prepoznavanje vrtač. V tem prispevku smo na primeru Agteleškega krasa v severovzhodni Madžarski preizkusili različne podatkovne baze in algoritme za prepoznavanje vrtač. Primerjali smo tri podatkovne baze: "TOPO" vrtače so razmejene na klasičen način z zunanjo zaprto plastnico na topografski karti v merilu 1: 10.000, "KRIG" vrtače so v istem merilu s pomočjo kriginga samodejno pridobljene iz digitaliziranih plastnic DMR, in "Li-DAR" vrtače so samodejno pridobljene iz DMR, ki je ustvarjen iz lidarskih podatkov. Najprej smo analizirali občutljivost avtomatske metode parametra "mejne globine", ki predstavlja prag, pod katerim se depresijske oblike štejejo kot "napake" in so zapolnjene. V konkretnem primeru smo glede na običajno velikost vrtače in ločljivosti DMR ugotovili, da je optimalna

A photo-statistical method has been developed to quantify the strength of directional clast fabric in various types of volcaniclastic mass-flow deposits. Fabric strength (R) is defined as the resultant vector length of clast alignment computed from clast angles visible on a vertical outcrop face. R can be obtained from photographs of an exposure via image analysis and statistical assessment with regard to clast number and direction of exposure face vs. paleoflow. Relative to traditional, manual field measurements, the photo-statistical method gives reproducible quantitative results that are independent of subjective clast selection. On average, one hundred and fifty clasts are the minimum number necessary to obtain reliable R values. For determining the strength of directional fabric, it is more accurate to measure randomly collected clasts than only the most elongated ones (normally the practice during manual measurements), because more elongated clasts display a stronger fabric. Clast size generally does not influence clast alignment. R values obtained from lower or upper portions of vertical exposure faces may show significant differences if pronounced imbrication is developed in the lower part of the beds passing upward to purely bed-parallel clast alignment. Bimodality caused by the coexistence of imbricated and bed-parallel clasts tends to reduce R values. The studied examples include (1) near-vent breccias, (2) block-andash flow deposits, and (3) mostly cohesive volcaniclastic debris-flow deposits from 49 selected exposures (24 in Hungary, 6 in France, 4 in Japan, 3 in New Zealand, 2 in Indonesia, and 1 in the U.S.A., Argentina, Chile, Turkey, and Romania, each). Near-vent breccias show a relatively weak fabric (R ഠ 28% on average). Volcaniclastic mass-flow deposits, regardless of their primary or secondary origin, develop a stronger fabric (R ഠ 46% on average) between 0.5 and 1 km from source. At distances more than 1 km, systematic improvement in clast alignment has not been identified. The presented photo-statistical method is applicable to any deposit that displays a preferred fabric.

The study of human-environment relationships in mountain areas is important for both theoretical and practical reasons, because many mountain areas suffer similar problems, namely depopulation, unemployment and natural hazards. Medium mountains constitute a special case within mountains because they are more populated but less attractive as tourist targets than high mountains. In this context, Apuseni Mts (Romania) is considered as a case study. In the present paper, we applied GIS-based, quantitative methods to characterize the strength and dynamics of human-environment interactions taking into consideration some environmental factors (elevation, relative height, slope, river distance, lithology, land cover, natural attractions) as well as historical population and recent tourism data. We found that population density has strong (r 2 >0.8) relationships with all relief factors (elevation, relative height, slope, river distance), and that best-fit functions are nonlinear. We outlined the varying demographic scenarios by elevation zones and interpreted the historically switching sign of population change versus elevation relationship. We proved that lithology, too, has an impact on the spatial distribution of population, though it is not independent from the relief effect. The land cover of that mainly cultural landscape is very strongly correlated with relief parameters (especially slope) that suggests a good adaptation. We pointed out the dominance of karst objects in the natural tourist potential of Apuseni Mts and explored further components (spas, heritage, towns) of real tourism as well. Finally, we concluded that the studied environmental settings in fact constrain the spatial framework of society, but socio-economic changes in history can be explained from the side of society, which conforms the theory of cultural possibilism.