Photos Show Strange Elongated Martian Crater

[mickw]

Photos just released by the European Space Agency give an up-close look at the strange, elongated Martian crater known as Orcus Patera.
The crater lies near the equator in Mars' eastern hemisphere, between the volcanoes Elysium Mons and Olympus Mons. It's big, measuring 380 km (236 miles) long, 140 km (87 miles) wide and about 2.3 km (1.5 miles) from rim to floor. [New photo of the crater.]
Astronomers have known about this odd crater for decades, but they still aren't sure how Orcus Patera formed. The word "patera" generally refers to deep, complex or irregularly shaped volcanic craters. But despite its name and its location near some big volcanoes, Orcus Patera's origin may not be volcanic

More:   Space.com

And more:   ESA