Becquerel is a 167 km-diameter crater at 22.1°N, 352.0°E on Mars, in Arabia Terra. It is named after Antoine H. Becquerel.
Photographs by the Mars Global Surveyor revealed layered sedimentary rocks in the crater. The layers appear to be only a few meters thick and show little variations in thickness. Recent studies with HiRISE have determined the exact thickness of the layers. The 66 layers measured showed one group of layers to average 3.6 metres (12 ft) and another group to average 36 metres (118 ft) in thickness. Patterns like this are usually produced on Earth through the effects of water; volcanic deposits would not produce ash or laval flows of such regular thickness and in any event there are no nearby volcanic vents.
There are cyclic variations in the thickness of the exposed sedimentary layers, possibly indicating cyclic variations in environmental conditions while the sediment was being laid down. Most of the layers are parallel to each other, suggesting they formed by vertical settling, but a few are cross-bedded, indicating that at the time that the layers were deposited the sediment was transported along the ground surface by wind or water. The sedimentary material appears to be easily eroded and active wind erosion may be continuing to the current day.
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Becquerel Crater layers with a fault, as seen by HiRISE.
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Mounds in craters showing layers are formed by the erosion of layers that were deposited after the impact.
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Layers in Monument Valley on Earth, for comparison.
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Quadrangle map of Oxia Palus labeled with major features. This quadrangle contains many collapsed areas of Chaos and many outflow channels (old river valleys). Becquerel is in the upper right.