Abstract
Previous studies on badland areas in the Vallcebre basin (High Llobregat) suggested that the erosion rates are controlled by weathering rate of mudrocks. The present work was started to characterize the physical weathering processes and rates in relationship with thermal and moisture conditions. The method used consists of the continuous monitoring of regolith temperatures at different conditions of aspect, depth and lithology (color), and the periodical sampling of regolith moisture and bulk density, the last taken as an indicator of the weathering status. Besides this quantitative information, the changes of the surface of the regolith have been monitored with the help of photographic techniques, using a especially designed tripod. To complete the field observations, a laboratory experiment is being performed, analyzing the volumetric changes suffered by undisturbed rock samples subject to thermal and moisture oscillations. The results obtained emphasize the role of frost action, especially during wet conditions. Aspect and lithologic differences introduce significant nuances in thermal regime and volumetric changes respectively.
Highlights
The method used consists of the continuous monitoring of regolith temperatures at different conditions of aspect, depth and lithology, and the periodical sampling of regolith moisture and bulk density, the last taken as an indicator of the weathering status
The aim of this work is to describe the research design set to analyze to the physical weathering processes of these materials, especially in relation with wet-drying and frost-melting alternances
Vallcebre basin lithology is dominated by mudrocks, these are continental clays from Trennp formation, dated at the Cretaceous-Palaeocene boundary
Summary
The method used consists of the continuous monitoring of regolith temperatures at different conditions of aspect, depth and lithology (colour), and the periodical sampling of regolith moisture and bulk density, the last taken as an indicator of the weathering status. Besides this quantitative information, the changes of the surface of the regolith have been monitored with the help of photographic thecniques, usíl'^g a especially designed tripod. Para complementar el estudio se diseñó un experimento de laboratorio, en el cual fueron sometidas varias muestras de roca inalterada a una serie de ciclos de variaciones térmicas e hldricas, y se cuantificaron los cambios producidos. Las diferencias de exposición y de características litológicas introducen matices significativos respectivamente en el régimen térmico y en los cambios volumétricos observados
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