Shaped pebbles and the direction of the wind that formed them ("fossil wind")
DOI:
https://doi.org/10.26485/BP/1966/15/6Keywords:
wind abrasion, pebbles surfaces, edges of pebbles, statisticsAbstract
Article in French.
ORIGINAL TITLE: Les cailloux façonnés et la direction du vent qui les a formés (vent "fossile")
- It is established that there are two essentially different types of surfaces – and, more importantly – two types of edges on pebbles: firstly, there are wind-abraded surfaces and untouched (virgin) surfaces; secondly, there are edges between two abraded surfaces (first type) and there are edges between an abraded surface and a virgin surface (second type). There is a fundamental difference in the orientation (with respect to wind direction) between edges of the first and second types. It is inherent impossible to determine wind direction based on the entirety of edge data and each edge type needs to be treated separately.
- Statistical examples are provided of the distribution of edge orientations in wind-shaped pebbles for all three cases: edges of the first type, edges of the second type, and all edges combined. The findings from Section I, that the dataset of “all edges combined” must be separated into two distinct subsets, is confirmed.
III. Wind direction. Past results are considered. The laws of A. Heim and A. Cailleux are discussed. A more differentiated law must be established, based on the fundamental distinction between the two types of edges.
- Remarks are presented on the theory of pebble shaping by wind action previously proposed by the author (C. R. Acad. Sci. Paris, Vol. 242, p. 1683, 1956) and on the existence of the two described types of surfaces and edges.
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