|
|
Distribution and pattern morphology of pseudomorphs of thermal-conctraction-cracks features in Austria
Dufek, Jaroslav ; Křížek, Marek (advisor) ; Margold, Martin (referee)
During the cold Pleistocene episodes, the territory of Austria was at the forefront of nearby Alpine glaciation. The unglaciated area of Austria was part of the Central European periglacial zone, in which permafrost developed. The distribution of Upper Pleistocene permafrost, its character, but also its time classification in the western part of the Pannonian Basin is still unclear. It is also because ideas about the characteristics of Upper Pleistocene permafrost in this area have so far been based mainly on indirect biological or lithological records such as pollen grains, malacofauna snails, or loess-paleosol sequences. Until now, the evidence of direct geo-indicators of paleo-permafrost has been relatively limited, with unique relict frost-wedges, cryoturbations, or sporadic remains of thermokarst lakes depressions and pingos. The results present a new database of relict frost-wedges in Austria, which was created based on published literary sources, but mainly based on aerial imaginary available on Google Earth Pro. The results significantly expand (by hundreds of localities) the existing knowledge about the occurrence of relict frost-wedges, which have so far been located in Austria purely on the basis of excavated profiles and soil probes. The found polygons of frost-wedge pseudomorphs are an...
|
|
|
Pingo morphology as a result of site and environmental characteristics
Kuznetsova, Evgeniia ; Křížek, Marek (advisor) ; Margold, Martin (referee)
This bachelor thesis deals with the study of pingos. The research part summarizes the morphological features of these landforms, the mechanisms of their origin and their developmental stages. The aim of this work is to describe the distribution of recent pingos on the Earth's surface, to characterize the limit natural conditions of pinog occurrence and to determine whether they are related to their morphology, prospectively to what extent. The results are based on a table containing individual environmental characteristics, which was created on the basis of a literature search. The results were further compared with the conclusions of previous studies. Pingos are of interest because they are indicators of the presence of permafrost and specific hydrological processes, and thus allow conclusions to be drawn about environmental conditions in the past and present.
|
|
|
Morphology of thermal-contraction-crack features and their pattern
Dufek, Jaroslav ; Křížek, Marek (advisor) ; Roman, Matěj (referee)
This bachelor thesis deals with phenomenon of periglacial landscape of continuos permafrost such as thermal-conctraction-crack polygons and forms of their secondary infill - ice, sand, soil and composite-wedge pseudomorphs. Upper Pleistocene thermal-conctraction-crack polygons are located in mid-latitudes all across the Europe. Most common geometry shapes of these polygons are orthogonal and hexagonal patterns. Pseudomorphs are commonly situated in areas of lowlands, river terraces, floodplains on slopes with angle up to 4ř. Their distribution is closely associated with the maximum extent of past permafrost during the last glacial episode (~17-25 ka BP). This pleistocene phase is known as last periglacial maximum (LPM; Vandenberghe et al. 2014). Creation of ice-wedges is primarily bound to present continuous permafrost, which the southernmost Pleistocene limit in Europe has been established to 47ř N (Black 1976, Vandenberghe et al. 2014). However, some research suggest, that with favorable local conditions, ice-wedges can develop also in arid climate and discontinuous permafrost zone and they can occur together with sand-wedges (Kasse 1998). It was also found that cold arid climate is not the only factor for sand wedge development, but great importance has also local variability of microrelief such...
|
guest ::
