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Thermal weathering of granite spheroidal boulders in a dry-temperate climate, Northern Dobrogea, Romania.
- Source :
- Earth Surface Processes & Landforms; Feb2017, Vol. 42 Issue 2, p259-271, 13p
- Publication Year :
- 2017
-
Abstract
- Weathering microforms associated with exfoliation were investigated on 40 granitic spheroidal boulders identified on Pricopan Ridge (Măcin Mountains) in order to establish a spatial distribution pattern. Continuous thermal monitoring allowed the frequency and intensity distribution assessment of short-term temperature changes triggered by summer storms, of intense day-night amplitudes and frost cycles across a uniform rounded boulder. Rock strength estimated by Schmidt hammer tests differentiates a significantly weaker resistance on the southern face of the boulders (rebound values of 27 to 33) in comparison with the northern face (43-50). The lowest resistance of the north-south cross-boulder profile corresponds to the southern gentle slopes (0°-45°) thus defining the most susceptible area to exfoliation and other weathering processes. It is argued that this low-resistant sector fits well with the maximum frequency and intensity of thermal processes recorded on the low and mid slopes (0°-45°) of the boulders south side, with small differences from one process to another, whilst the sector of 20° to 30° south corresponds to the peak activity of all. In accordance, the overlay map of exfoliated surfaces places the high frequency area on a spherical cap developed similarly (between 5° north and 45° south). The smallest exfoliated surfaces normally appear around 30° south and are inferred to extend in time both to the boulder top and downslope. The correlations between the frequency/intensity maps of thermal processes and the frequency map of exfoliated surfaces point to a complementary action in the exfoliated surfaces development of the short-term temperature changes and diurnal cooling and heating due to the directional insolation effect, as similarly inferred in the development of meridional cracks. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Subjects :
- MICROFORMS
EXFOLIATION (Geology)
GRANITE
STORMS
GLACIAL crevasses
Subjects
Details
- Language :
- English
- ISSN :
- 01979337
- Volume :
- 42
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Earth Surface Processes & Landforms
- Publication Type :
- Academic Journal
- Accession number :
- 121063068
- Full Text :
- https://doi.org/10.1002/esp.3984