This entire landscape is covered by lava flows. Almost all of vast Amazonis Planitia is covered by lava flows, an area comparable to that of the entire continental United States.
Amazonis Planitia is also one of the flattest places on Mars, because of the thick lava fill. Most of this lava was likely erupted in relatively short periods of time, perhaps thousands of years. Earth has also experienced relatively short-lived pulses with very high lava eruption rates, and these pulses precisely match the dates of four mass extinction events and a dozen of so smaller extinction peaks. [More at link]