The Phaethontis quadrangle lies between 30° and 65° south latitude and 120° and 180° west longitude on Mars. This latitude range is where numerous gullies have been discovered. An old feature in this area, called Terra Sirenum lies in this quadrangle; Mars Reconnaissance Orbiter discovered iron/magnesium smectites there.[3] Part of this quadrangle contains what is called the Electris deposits, a deposit that is 100–200 metres (330–660 ft) thick. It is light-toned and appears to be weak because of few boulders.[4] Among a group of large craters is Mariner Crater, first observed by the Mariner 4 spacecraft in the summer of 1965. It was named after that spacecraft.[5][page needed] A low area in Terra Sirenum is believed to have once held a lake that eventually drained through Ma'adim Vallis.[6][7][8][page needed] Russia's Mars 3 probe landed in the Phaethontis quadrangle at 44.9° S and 160.1° W in December 1971. It landed at a speed of 75 km per hour, but survived to radio back 20 seconds of signal, then it went dead. Its message just appeared as a blank screen.[9][page needed]
^Davies, M.E.; Batson, R.M.; Wu, S.S.C. (1992). "Geodesy and Cartography". In Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; et al. (eds.). Mars. Tucson: University of Arizona Press. ISBN978-0-8165-1257-7.
^Blunck, J. 1982. Mars and its Satellites, Exposition Press. Smithtown, N.Y.
^Grant, J.; Wilson, Sharon A.; Noe Dobrea, Eldar; Fergason, Robin L.; et al. (2010). "HiRISE views enigmatic deposits in the Sirenum Fossae region of Mars". Icarus. 205 (1): 53–63. Bibcode:2010Icar..205...53G. doi:10.1016/j.icarus.2009.04.009.