Planetary Geology by Angelo Pio Rossi & Stephan van Gasselt

Author:Angelo Pio Rossi & Stephan van Gasselt
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Wind can create wind streaks in presence of topographic obstacles. Wind streaks can form either by deposition or erosion of material. A wind streak can form when material is transported from an butte, like a volcano, depositing grain of different albedo than those of surrounding plains; i.e. depositional wind streak. But a wind streak can also form when the topography protects the shadow behind it from the accumulation of eolian material everywhere else, i.e. differential deposition streaks, as observed on Venus (Fig. 9.4c). This process does not require the volcano to be active. Ash deposition due to the volcanic activity itself can be distinguished by an aureole larger than the shadow from the volcano. Wind streaks can form also by erosion of material deposited. Obstacles such as rock outcrops or impact craters play the role of shadows protecting from erosion the deposits in the lee of wind (Fig. 9.4d). Wind streaks of that category are frequent on Mars. They are light-toned as due to residual dust deposits preserved from erosion by wind. Wind streaks can reach tens of kilometers in length but are usually thin. The lack of streaks on thermal images of the same area shows that those streaks do not exceed a few centimeters in thickness (Fig. 9.4e, f).

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