Surface Features Overview
• N vs. S differences
• Tharsis Plateau
• Volcanoes
– Shield Volcanoes
– Patera Volcanoes
• Planitia
• Valles Marineris
– Outflow Channels
• Polar Ice Caps
• Canals?
• Evidence of Past
Water
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North vs. South
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Typical N. hemisphere region
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Typical S. hemisphere region
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High Elevation Region
rst.gsfc.nasa.gov
One ‘continent’: Tharsis, about the size
of Africa.
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Olympus Mons
Alba Patera (Volcanoes)
Aligned Shield Volcanoes
Valles Marineris6
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Volcanoes on Mars
• 2 types of volcanoes: shields and pateras.
• Shield volcanoes are wide and low.
• What does this tell you about the
consistency or ‘viscosity’ of the lava?
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www.bbc.co.uk
Mars ‘typical’
volcano.
Earth has shield volcanoes,
but also has cone-shaped or
“strato-volcanoes”, made from
thicker, high-viscosity, lava.
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Runnier basaltic lava, non-explosive eruptions
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Mt. Kilauea – large caldera
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The main shield volcanoes
on Mars are Olympus Mons,
and the aligned shield
volcanoes:
Ascraeus Mons
Parvonis Mons
Arsia Mons
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Olympus Mons
• If one edge were in Lancaster, the
opposite edge would be in Chicago!
• At 15 miles or 80,000 feet, the crater is
above Mars’ thin atmosphere.
• You could stand on Mars’ surface and be
in space at the same time!
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Olympus Mons
• 27 kilometers above mean datum.
– 3x higher than Mt. Everest
– 2.6x taller than Mauna Kea (from sea floor
base to caldera)
• Slope is only 2.5o.
• Surrounded by an escarpment up to 6 km
high.
• Caldera is 85 km x 60 km.
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Olympus Mons
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How did they get so big?
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The other type of volcano
is a patera – a huge
crater with almost
no slope around it.
Larger, but lower,
than shield volcanos.
Apollinaris patera
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http://www.the-planet-mars.com/pictures/Apollinaris-Patera-volcano.jpg
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Alba Patera – almost no slope, huge caldera
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From high to low – the Planitia
• Hellas Planitia
– 9 km deep
– 2100 km across
– rim is 1.25 km
high
– impact debris
thrown out to a
distance of 4000
km
• Argyre Planitia
– 5 km deep
– 1800
– several deep
channels flow
into it from
surrounding
terrain
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Hellas
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www.astro.virginia.edu/class/oconnell/astr121/im/global-altim-hel-hem.jpg
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Light-colored Hellas Planitia
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Valles Marineris
• Huge canyon system
– 4000 km long
– up to 600 km wide
– up to 10 km deep (6-7 times deeper than our
Grand Canyon)
– NOT formed by flowing water! (but possibly
modified by water)
– How was it formed?
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www.astro.virginia.edu/class/oconnell/astr121/im/ValMar-v-GrCan-TSmith-uwash-enl.jpg
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How was it formed?
qnck.imageg.net
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rst.gsfc.nasa.gov/Sect19/FHA-01278sub_bw2b.JPG
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• Near the eastern end of the Valles Marineris
are huge canyons called “outflow channels”.
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Ravi Vallis
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How did they form?
• Here on earth, in Washington State, there
are similar rugged canyon-lands called the
Scablands.
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www.uwsp.edu/geo/projects/geoweb/participants/dutch/GeoPhotoVtrips/Scablands
www.kidscosmos.org/kid-stuff/mars-trip-graphics/
flood-channel-map-sml.jpg
The Scablands of
Washington State, USA
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Catastrophic Flooding
• Glacial dam across a river in Washington
State.
• Lake Missoula.
• Pressure of the water broke through the
ice, releasing hundreds of cubic miles of
water all at once.
• Scablands carved in just a few weeks.
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