National Repository of Grey Literature 125 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Configurations of the North American Ice Sheet Complex reflected in sediment dispersal trains
Jandová, Anna ; Margold, Martin (advisor) ; Křížek, Marek (referee)
Glacial dispersal trains are trails of debris eroded from a distinctive bedrock source and transported downflow by a glacier. This thesis aims to compare the dispersal directions with the estimates of ice flow direction over time and to analyze possible influences on the dispersal patterns. A total of 131 dispersal trains were analyzed and compared with 34 configurations of the North American Ice Sheet Complex during the Late Gauss chron (3,6-2,6 Ma BP) and the Last Glacial Period (Wisconsinoan glaciation), including the subsequent glacial retreat (115-6 ka BP). According to the results, the possible effect of the last glaciation that affected the dispersal trains or the direction of the prevailing ice flow on the direction of dispersal cannot be confirmed. There was no better evidence for any other assumption, such as the effect of the direction of the prevailing ice flow during the Last Glacial Maximum.
Possibilities of remote geomorphological mapping of dolines in the conditions of the Bohemian Karst
Hochmanová, Lucie ; Křížek, Marek (advisor) ; Uxová, Tereza (referee)
The study of karst areas is important for the inventory of local forms and their subsequent protection. The aim of this bachelor's thesis is to create a database and determine the morphometric characteristics of dolines in the protected landscape area of the Czech Karst above DEM 5G and to evaluate the possibilities of remote mapping of these karst forms. The mapping was based on training data from the Moravian Karst, but the morphometry was found to be different from the dolines in the Czech Karst. A total of 74 dolines were found, of which 58 were mapped on DEM 5G and 16 were added from the literature. Average values of morphometric characteristics were found for length 30.34 m, width 18.65 m, depth 2.57 m and circularity 0.663. Half of them show a linear arrangement and an elongated oval shape, which may indicate a continuity with the fractures. The majority of all mapped dolines form clusters on Devonian limestones in the northwestern area of the Bohemian Karst Protected Landscape Area. As a result, two map outputs with possible locations of dolines and a database with morphometric characteristics are available. Keywords: doline, Bohemian Karst Protected Area, digital elevation model, remote sensing mapping
State of the art on lightning activity induced by volcanism
Tesař, Matouš ; Popová, Jana (advisor) ; Křížek, Marek (referee)
The thesis presents a state of the art of existing knowledge and findings related to the lightning inducted by volcanic activity. First the thesis briefly characterizes lightning which occurs in thunderstorms. The chapter also presents mechanisms of lightning occurrence and methods of lightning detection. The main part of the thesis contains a literature review on the characteristics of lightning which occurs in relation to volcanic activity. It also provides classification of volcanic lightning and mechanisms of its occurrence. Furthermore, the chapter describes methods which are used to detect volcanic lightning. It also contents methods of investigation of volcanic lightning and laboratory experiments, which aim at deepening theknowledge on this phenomenon. Moreover, the chapter also provides a brief outline of expected future research on volcanic lightning. The thesis presents several ways by which volcanic lightning affects the Earth's atmosphere and surface, and the affected volcanic ash particles. Based on findings provided by the literature, the thesis discusses and compares lightning produced during in thunderstorms with volcanic lightning. Key words: lightning, volcanism, state of the art, detection
Position, morphometry and surface weathering of tors in the Hrubý Jeseník Mts.
Tomíčková, Lucie ; Křížek, Marek (advisor) ; Létal, Aleš (referee)
The diploma thesis analyzes the positional and morphometric characteristics of tors in Hrubý Jeseník Mts. and their surface weathering. As a part of the distance mapping, tors' spatial distribution was determined using 5th generation digital elevation model and aerial orthophotos. Selected morphometric information (elevation, slope, aspect, and solar radiation) were determined using the digital elevation model. During field work, descriptive morphometric properties of tors (maximum height, width, and length) and their surface weathering were evaluated. Surface weathering was analyzed using Schmidt Hammer test and the method of measuring the veins and weathering pits morphological characteristics. Based on statistical analysis, the weathering characteristics were evaluated in relation to tors' morphometric and topographic characteristics. A total of 511 tors were identified in Hrubý Jeseník Mts. by distance mapping. Tors occurrence and distribution is related to the slope, lithology, orientation, and solar radiation. The majority of the tors are located below the summit at elevation of 900-1000 m a. s. l. There is more than 60% of metagranite and gneiss tors. Tors' height ranges from 1.6 to 30 m. Surface weathering have been measured in 58 tors. Microforms morphology measuring revealed the influence...
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...
Spatial distribution and morphological analysis of river islands in the Czech Republic
Růžičková, Veronika ; Křížek, Marek (advisor) ; Kalvoda, Jan (referee)
The topic of this thesis is spatial distribution of mid-channel bars on Czech rivers. Its aim is to describe the laws of their morphology and distribution in the river channel using remote analysis of aerial photographs. Czech islands originate in places where the flow slows down, mainly in bends and around obstacles in the channel. Their main axis is in the most cases parallel to the course of the streamline. The width of the channel and the presence of vegetation have an undeniable effect on the size of the islands. The presence and morphological characteristics of the river islands also reflect human intervention in the course of the river channel, where does it matter whether it is an artificial channel with hardened banks or a natural-looking one. Key words: fluvial geomorphology, mid-channel bars, river islands, sedimentation, Czech rivers

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