Acidalia Planitia

Acidalia Planitia is a large, low-lying region in the northern hemisphere of Mars. It is characterized by its sparse cratering, indicating it formed after Mars's early period of heavy bombardment. This vast area is part of the northern plains, which have very little relief and include other regions like Chryse Planitia and Utopia Planitia.1

The terrain within Acidalia Planitia includes knobby areas with small hills and smoother plains, possibly formed from ancient buried crater surfaces. Some areas show polygonal fracture patterns, similar to permafrost regions on Earth, while others have a thumbprint-like texture that might suggest the past presence of stagnant ice. The origin of these plains is debated, with some scientists suggesting they are volcanic lava flows, while others propose they were once covered by large bodies of water fed by ancient floods.1