Margaritifer Terra is an ancient, heavily cratered region of Mars. It is centered just south of the Martian equator at 4°54′S 25°00′W / 4.9°S 25°WCoordinates: 4°54′S 25°00′W / 4.9°S 25°W and covers 2600 km at its widest extent. The area reveals "chaos terrain", outflow channels, and alluvial plains that are indicative of massive flooding. Wind erosion patterns are also in evidence. A region within the terra shows some of the highest valley network densities on the planet. The Ares Vallis is another notable feature, where the flood and flow patterns appear in evidence; it was the landing site of Mars 6 and NASA's Mars Pathfinder.
Holden and Eberswalde, craters in Margaritifer Terra are thought to be old lakes because they contain deltas and the mineral iron/magnesium smectites which need water to form. 
Margaritifer Terra was named in 1979, after the Pearl coast, south India.
- ^ Blue, Jennifer. "Margaritifer Terra". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
- ^ Murchie, S. et al. 2009. A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter. Journal of Geophysical Research: 114.