Despite being 2.3 million years old, the crater and its secondaries — some of which are carved into lava flows originating from the summit of the extinct Martian volcano Elysium Mons — are ...

with the exception of features like Olympos Mons (a 13.6-mile-high shield volcano) and Elysium Mons (Mars' third-tallest mountain). Dividing the two hemispheres is the meandering dichotomy ...