The plain that gave its name to an entire chapter of Mars' history.
Hesperia Planum is a vast ridged lava plateau whose crater density defines the Hesperian period (~3.7–3.2 billion years ago), the middle of Mars' three geologic epochs. Its surface is scored by wrinkle ridges from compressed volcanic flows.
Claim your plot here →When geologists needed a yardstick for the middle age of Mars, they chose Hesperia Planum. Its heavily ridged basalt records a time when the planet's great volcanic plains were being laid down, after the battered Noachian highlands but before the quiet Amazonian deserts. Every dated surface on Mars is measured against this ground.
The plain is dominated by wrinkle ridges, long buckles formed as thick lava sheets cooled and the crust contracted. Nearby sits Tyrrhenus Mons, an ancient low volcano thought to have fed these flows with fluid, ash-rich eruptions. Together they preserve a snapshot of Mars in transition from a wet, active world to a colder one.