<p>Possible Clay-Rich Terrain at the Mouth of Nirgal Vallis — Nirgal Vallis is a long river channel, whose western half is a branched system, but the eastern half is a tightly sinuous, deeply entrenched valley. We know that water once flowed here and the presence of clays helps to confirm that. But how much and for how long?
</p><p>NASA/JPL/University of Arizona (256 km above the surface; less than 1 km top to bottom and north is to the right)
</p><p>Source: <a rel="nofollow" class="external text" href="https://www.uahirise.org/ESP_018043_1500">www.uahirise.org/ESP_018043_1500</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/people/71688597@N05">UAHiRISE (NASA)</a>
2018-09-24 11:31
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/uahirise-mars/44892712431/">ESP_018043_1500</a>