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- Title
Frost sorting on slopes by needle ice: A laboratory simulation on the effect of slope gradient.
- Authors
Anyuan Li; Norikazu Matsuoka; Fujun Niu
- Abstract
Following a previous attempt to reproduce miniature sorted patterns on a level surface, we report the results of a fullscale laboratory simulation on frost sorting produced by needle ice activity on inclined surfaces. Four models, with different slope gradients (5°, 7°, 9°, 11°), were designed. Stones 6mm in diameter placed in a grid covered 20% of the surface of frostsusceptible water-saturated soil. These models were subjected to 20-40 freeze-thaw cycles between 10°C and -5°C in 12 hours. The evolution of surface patterns was visually traced by photogrammetry. Needle ice growth and collapse induced downslope movement and concentrations of stones. A model produced incipient sorted circles on a 5° slope, whereas it resulted in three distinct sorted stripes on a 7° slope. The average diameter or spacing of these forms is 9.7-19.4 cm, comparable to those in the field dominated by diurnal freeze-thaw cycles. Surface parallel displacements of stone markers were traced with motion analysis software. The observed downslope stone displacements agree with those expected assuming that surface soil and stones move by repeated heaving perpendicular to the surface and vertical settlement due to gravity, although the growth of curved needle adds complexity to the overall displacements.
- Subjects
FROST; FRAZIL ice; SOIL moisture; PHOTOGRAMMETRY; SIMULATION methods &; models
- Publication
Earth Surface Processes & Landforms, 2018, Vol 43, Issue 3, p685
- ISSN
0197-9337
- Publication type
Article
- DOI
10.1002/esp.4276