The soft, wind-carved enigma of the Martian equator.
Medusae Fossae is one of the strangest terrains on Mars: a vast, soft, easily-eroded deposit stretching for thousands of kilometres along the equator. It is radar-transparent and so lightly bound that wind has sculpted it into ridges and yardangs — yet scientists still argue whether it is volcanic ash or a colossal ice deposit.
Claim your plot here →The formation is a fine-grained, layered blanket that wind has carved into dramatic grooves called yardangs. Radar sounding shows the material is unusually low in density and lets signals pass through it — a property that could indicate either porous volcanic ash or buried, dusty water ice.
If Medusae Fossae is ash, it may be one of the largest explosive volcanic deposits in the solar system. If it is ice, it could hold a globe-spanning water reserve. Either way it is a leading candidate source for much of the fine dust that circulates around Mars — making this quiet, mysterious region one of the planet's most consequential.
Its constant wind erosion may supply a large share of the fine dust that coats the entire planet.
If ash, it could rank among the biggest explosive volcanic deposits known anywhere in the solar system.