Athabasca Vallis Circles

Have fun with this new one from MSSS:

http://www.msss.com/mars_images/moc/2003/06/27/index.html

Athabasca Vallis is a large channel system cut by catastrophic floods in the Cerberus region, south of Albor Tholus, on Mars. The age and history of Athabasca Vallis is the subject of some current debate in the Mars science community; some consider it to be geologically young, others suggest the valley is ancient and has been exhumed after being buried for an unknown, but considerable, length of time. The valley system contains evidence suggesting that lava flows--or, perhaps, mud flows--as well as water, once poured through this area. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presents another puzzle: odd, somewhat circular features on the floor of the Athabasca Vallis near 9.7°N, 203.7°W. Their cause is unknown; some of the landforms nearby (not visible here) suggest the circular features are exhumed. This picture was taken in April 2003; it covers an area 1.7 km (1 mi) across and is illuminated from the left.

These circular mounds look reminisent of extinct undersea volcanoes.

BD