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Lichenometry as a method and its relevance
Pelant, Filip ; Svoboda, David (advisor) ; Halda, Josef (referee)
Lichenometry is a constantly developing method (or set of methods) of relative and absolute dating of geological and anthropogenic formations, based on analysis of crustose lichens. It operates with an assumption that the larger the thallus is, the older the lichen is. But the relation between size and age (known as "growth rate") is far from being linear, and lichenometry has long attempted to find a way of describing this relation properly and universally. For this purpose, lichenometry uses direct and indirect methods - by repeated measurements of the same lichen individuals over time, or by comparison to individuals growing on substrates of known age (e.g. by using radiocarbon method). There is an ongoing controversy about aging and age calibration since the inception of the lichenometry field, but especially in this century. Strong criticism has been expressed about lichenometry, questioning the very principles of the method and consequently undermining all the results of lichenometry so far. The goal of the present bachelor thesis is to present the method with its approaches and to address the criticism. At the same time I aim to highlight recent trends in the field that seek to improve the methods toward more reliable lichenometric dating, and to encourage the use of the methods as so...
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The Glacial Retreat in the Cordillera Blanca since the Littel Ice Age
Dobíhal, Michal ; Vilímek, Vít (advisor) ; Emmer, Adam (referee)
Michal Dobíhal Studijní program: Geografie Studijní obor: Fyzická geografie a geoinformatika Bakalářská práce Vedoucí práce, školitel: Doc. RNDr. Vít Vilímek, CSc. The glacial retreat in the Cordillera Blanca since the Little Ice Age ABSTRACT: The term Little Ice Age refers to a cooling period of time, as a result of this cooling mountain glaciers experienced significant advance in many parts of the world. Conventionally, the period between the 16th century and the middle of the 19th century is stated for the Little Ice Age, but its course and time placement differs in individual world regions. Based on research of scientific literature, this thesis aims at describing correct time placement of the Little Ice Age in the southamerican mountain range Cordillera Blanca and the expanse of the glacier retreat since its maximum till the present. Methods of lichenometry used for dating "Little Ice Age" moraines are mentioned as well. In the analytical part, the area of the glaciation of selected glaciers from the Little Ice Age maximum and from the present is compared using polygon measurement and satellite images. The extrapolation of this method is subsequently made on other selected glaciers, whose moraines have not been dated yet. Keywords: Cordillera Blanca, Little Ice Age, glacial retreat, moraine, lichenometry
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