Acidalia Planitia is a plain on Mars, between the Tharsis volcanic province and Arabia Terra to the north of Valles Marineris, centered at 49.8°N 339.3°E. Most of this region is found in the Mare Acidalium quadrangle, but a small part is in the Ismenius Lacus quadrangle. The plain contains the famous Cydonia region at the contact with the heavily cratered highland terrain.
A gully found in the Bamberg Crater, which resides in Acidalia Planitia
Possible mud volcano in Acidalia Planitia
Arabia Terra is a large upland region in the north of Mars that lies mostly in the Arabia quadrangle, but a small part is in the Mare Acidalium quadrangle. It is densely cratered and heavily eroded. This battered topography indicates great age, and Arabia Terra is presumed to be one of the oldest terrains on the planet. It covers as much as 4,500 km (2,800 mi) at its longest extent, centered roughly at 21°N 6°E with its eastern and southern regions rising 4 km (13,000 ft) above the north-west. Alongside its many craters, canyons wind through the Arabia Terra, many emptying into the large northern lowlands of the planet, which borders Arabia Terra to the north.
THEMIS daytime infrared image mosaic showing Eden Patera (at center), one of the proposed volcanic caldera complexes in Arabia Terra, and its surroundings
Ice sheet in Oxus Patera, a caldera in Arabia Terra. The scalloped nicks along the spines of the caldera's ridges are likely cracks caused by the expansion and contraction of ice.
Layers in Tikhonravov Crater in Arabia, as seen by Mars Global Surveyor (MGS). Layers may form from volcanoes, the wind, or by deposition under water. The craters on the left are pedestal craters. Some researchers believe this crater once held a massive lake.
Tikhonravov Crater floor, as seen by Mars Global Surveyor. Click on image to see dark slope streaks and layers.
