Athabasca Valles
Athabasca Valles is a valley on Mars, and is one of the youngest known channels cut into its surface by catastrophic flooding.[1] The flood produced distinctive "teardrop" landforms similar to those found in the channeled scabland region of the United States on Earth.[2] It is thought that these landforms were produced though depositional processes wherein the floodwaters dropped sediment behind resistant bedrock outcroppings and craters.[3] The source of water for the flood is thought to be Cerberus Fossae.[3]
The very high spatial resolution images from the HiRISE camera onboard the Mars Reconnaissance Orbiter have revealed that all the flood features are draped by lava flows (Jaeger et al., 2007 [4]). The floor of the valley is peppered with thousands of small cones and rings formed as steam exploded through the lava flow. Because the flood-carved surface is now covered by lava, it is no longer easy to determine the age of the water floods that passed through Athabasca Valles. It is plausible that the flood was triggered by rising magma and hence the water flood and lava flows are essentially contemporaneous, but this has not been confirmed.
Around 80% of the craters in Athabasca Valles are secondary craters from the impact that created Zunil crater. [5]
Images from HiRISE in the Athabasca Valles region show features formed by the expansion and contraction of ice. Because these features occur in a channel that was active only 2 million years ago, the features hint at a warmer climate in which ice melted to form liquid water, then refroze.
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Athabasca Valles showing source of its water, Cerberus Fossae. Note streamined islands which show direction of flow to south. -
Athabasca Valles Streamlined Form, as seen by HiRISE.
References
- ^ Hydraulic modelling of Athabasca Vallis, Mars / Modelisation hydraulique de Athabasca Vallis, Mars
- ^ Mars Global Surveyor MOC2-322 Release
- ^ a b http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1066.pdf
- ^ Jaeger, W.L.; et al. (2007). "Athabasca Valles, Mars: A lava-draped channel system". Science. 317: 1709–1711. doi:10.1126/science.1143315.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^ McEwen, A.S.; et al. (2005). "The rayed crater Zunil and interpretations of small impact craters on Mars" (PDF). Icarus. 176: 351–381. doi:10.1016/j.icarus.2005.02.009.
{{cite journal}}: Explicit use of et al. in:|author=(help)
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