You are not logged in.
The crater on the rim of Victoria crater on the right side of this
image very definitely gives the impression of a volcanic crater rather
than an impact crater:
Victoria Crater on Mars.
http://antwrp.gsfc.nasa.gov/apod/ap061002.html
An analogue of the Victoria crater complex might be Crater Lake,
Oregon:
Crater Lake, Oregon
Crater Lake National Park
http://vulcan.wr.usgs.gov/Volcanoes/Cra … ework.html
A curious aspect of Victoria crater is its irregular rim with
alternating promontories and alcoves. The rim of Crater Lake, Oregon
might be analogous to this:
Crater Lake, Oregon.
http://earthobservatory.nasa.gov/Newsro … g_id=17401
Although in the case of Crater Lake, the irregular rim is only
apparent on half of the rim, the other half having a more rounded
appearance.
The volcanic crater on the rim of Victoria might be analogous to
Wizard Island and Mount Scott in the Crater Lake complex, labeled in
the preceding image.
The crater forming Crater Lake formed from the collapse of a volcano.
Then an analogous scenario would account for the origin of Victoria
crater on Mars. Then Victoria itself might be a volcanic crater.
Then these two craters might give us a chance for the first time to
observe the interior of a volcanic crater on Mars.
Bob Clark
Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):
“Anything worth doing is worth doing for a billion dollars.”
Offline
The resemblance of the orbital photographs is eerie.
However, I do wonder if volcanism or impact shaped the final form of either crater's edge.
Although we won't know for certain until we can get the rover up to some of those outcrops, what rocks are visible from Opportunity's current vantage appear shocked, just like at every other impact crater it has visited. So, I'm willing to say that an impact was what originally dug out the hole.
I'm not willing to say it formed the "bays" on the crater edge, though. As your pictures show, there's nothing unique about them in comparison to Crater Lake. It's entirely possible that both features were shaped by the same factor, which clearly does not require an impact crater.
This is a very interesting observation, RG.
"We go big, or we don't go." - GCNRevenger
Offline
According to Geological History of Crater Lake, c. 1912 and other data on the national park website, the Crater Lake feature is less than 200000 years old, and was created by subsidence after an eruption rather than by being blasted out of the rock.
"We go big, or we don't go." - GCNRevenger
Offline