Vallis (planetary geology)

Vallis or valles /ˈvælɪs/ (plural valles /ˈvæliːz/)[1] is the Latin word for valley. It is used in planetary geology to name landform features on other planets.

Scientists used vallis for old river valleys they discovered when they sent the first probes to Mars. The Viking Orbiters caused a revolution in our ideas about water on Mars; finding huge river valleys in many areas. Space craft cameras showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers.[2][3][4] Some valles on Mars (Mangala Vallis, Athabasca Vallis, Granicus Vallis, and Tinjar Valles) clearly begin at graben. On the other hand, some of the large outflow channels begin in rubble-filled low areas, called chaos or chaotic terrain. It has been suggested that massive amounts of water were trapped under pressure beneath a thick cryosphere (layer of frozen ground), then the water was suddenly released, perhaps when the cryosphere was broken by a fault.[5][6]

  1. ^ In Latin, the singular is valles (with a short 'e') or vallis, and the plural is valēs with a long 'e'.
    valles. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
  2. ^ Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 978-0-8165-1257-7. Retrieved 7 March 2011.
  3. ^ Raeburn, P. 1998. Uncovering the Secrets of the Red Planet Mars. National Geographic Society. Washington D.C.
  4. ^ Moore, P. et al. 1990. The Atlas of the Solar System. Mitchell Beazley Publishers NY, NY.
  5. ^ Carr, M. 1979. Formation of martian flood features by release of water from confined aquifers. J. Geophys. Res. 84: 2995-3007.
  6. ^ Hanna, J. and R. Phillips. 2005. Tectonic pressurization of aquifers in the formation of Mangala and Athabasca Valles on Mars. LPSC XXXVI. Abstract 2261.