Quantitative study of a rapidly weathering overhang developed in an artificially wetted sandstone cliff

0475846 - GLÚ 2018 RIV US eng J - Článek v odborném periodiku
Bruthans, J. - Filippi, Michal - Schweigstillová, Jana - Řihošek, J.
Quantitative study of a rapidly weathering overhang developed in an artificially wetted sandstone cliff.
Earth Surface Processes and Landforms. Roč. 42, č. 5 (2017), s. 711-723. ISSN 0197-9337. E-ISSN 1096-9837
Grant CEP: GA ČR GA13-28040S
Institucionální podpora: RVO:67985831 ; RVO:67985891
Klíčová slova: sandstone overhang * retreat * frost weathering * erosion rate * stress
Obor OECD: Geology; Geology (USMH-B)
Impakt faktor: 3.722, rok: 2017

Those factors controlling the weathering and erosion of sandstone on the field scale are still not well understood. In this study, a specific sandstone overhang (and its surroundings) with artificially induced and extremely high erosion rates was subjected to a complex investigation. Contrast between the erosion rate of the wet and dry portions of the same cliff enabled isolation of the factors responsible for rapid sandstone retreat. Erosion rates, moisture, and salt content, as well as suction were monitored in the field. Mineral phases and water chemistry were analyzed. The measurement of tensile strength, laboratory frost weathering tests, and numerical modeling of stress were performed. The acquired data show that an increase of moisture content in pores in the area of the studied overhang decreased tensile strength of the sandstone to 14% of its dry value, and increases the sandstone weathering and erosion rate, by nearly four orders of magnitude, compared to the same sandstone under natural moisture conditions outside of the cliff area. Consequently, frost weathering, in combination with wetting weakening was found to play a major role in weathering/erosion of the sandstone cliff and overhang. Frost weathering rate in both the laboratory and field increases up to 15 times with decreasing gravity-induced stress. The results also indicate that sandstone landforms in temperate climates may potentially develop very rapidly if the pore space is nearly saturated with water, and will later remain relatively stable when the moisture content decreases. As a general implication, it is suggested that overhangs in Central Europe (and elsewhere) might be the result of rapid frost weathering of nearly saturated sandstone during the Last Glacial.
Trvalý link: http://hdl.handle.net/11104/0272468