Mars: Fourth Order Landscapes

C.M. Rodrigue, 2016Geography, CSULB

Mars: Fourth Order Landscapes

Geography 441/541S/16

Dr. Christine M. Rodrigue



• The “Orders of Relief” for Martian Landscapes– The first order was the great crustal dichotomy and

Tharsis:• Northern lowlands: ~ 1/3• Southern highlands: ~2/3• Tharsis Rise: ~1/4

– The second order was the large regional features: • Elysium Rise• The largest craters: Hellas, Argyre, Isidis, Utopia• Valles Marineris• The polar ice caps



• The “Orders of Relief” for Martian Landscapes– The third order was the somewhat smaller major regions

associated with the araeological eras:• In many ways, this is a cross-cutting category• It addresses the “geological column” or relative ages of all

Martian landscapes in terms of the three regional units that gave the three-part sequences of Mars’ evolution their names:– The Noachian Era– The Hesperian Era– The Amazonian Era


Mars: Fourth Order Landscapes• The “Orders of Relief” for Martian Landscapes

– The fourth order is “in order” now:• These are smaller features (a few kilometers to a few hundred km):• They are landscapes dominated by one or two processes

– Fluvial valleys – Sapping alcoves– Outwash channels– Linear fossæ– Folded and faulted mountains of Thaumasia– Lava tubes – Layered mesas – Patterned ground – Wind abraded/etched landscapes– Dune fields – Evidence of mass wasting


Mars: Fourth Order LandscapesSecondary cratering issue: (W.K. Hartmann painting

http://psi.edu/hartmann/)


Mars: Fourth Order Landscapes• Secondary cratering issue:

– Secondary cratering from a primary impact event can be hard to detect– odd-shaped craters are often

described as secondaries– lower velocity impacts don't

produce a symmetrical detonation



• Secondary cratering issue:– Secondary cratering from a primary impact event can be hard to detect

just from odd shapes– Plot complication: really low angle impacts, <15° , can also produce odd

shapes, if rarely° Orchus Patera (340 x 140 km)?° Terra Sabæa near Huygens (80 x 20

km)° crater N of Acheron Fossæ



• Secondary cratering issue:– Secondary cratering often

produces linear chains of craters– THEMIS, +19 at

348E( Trouvelot Crater)– MOC, +16 at 325° (Margaritifer

Terra) – MRO image of Candor Chasma

wall with this weird chain cutting across at an angle to gravity

– This can result from forces in the ejecta curtain organizing the debris into linear, unsorted rays, as seen (and preserved) on the moon



• Secondary cratering issue:– My attempt to detect crater rays

– 6th order nearest neighbors– calculated azimuths from each crater to its 6th order nearest

neighbors– compensated for random “alignments” by counting craters at

various standards of “alignment” and comparing the counts with the binomial distribution using a Chi-square goodness-of-fit test

– a <15° departure of azimuths from that of the nearest neighbor pair was considered “aligned”



– My attempt to detect crater rays came out kinda groovy!



– Robbins and Head (2011)– mapped crater clusters– drew great circle routes– several great circles converged on Lyot Crater north of Arabia Terra



• Folded and Faulted Mountains:– Grabens and folds

– Thaumasia Highlands


Mars: Fourth Order Landscapes• Lava Tubes:

– Lava flows under a crust, which may collapse– Pavonis– Check out catena


Mars: Fourth Order Landscapes• Lava Tubes:

– Lava flows under a crust, which may collapse– Pavonis– Check out catena

inside a graben or dike or lava tube


Mars: Fourth Order Landscapes• Layered Mensæ:

– Resistant caprocks protect less resistant materials below– Artist: Marilynn Flynn www.tharsisartworks.com



– Resistant caprocks protect less resistant materials below– Cydonia and the Face on Mars



– Resistant caprocks protect less resistant materials below– Cydonia– Face with HRSC and MOC



– Resistant caprocks protect less resistant materials below– The heart on Mars south polar region, ~255 m across


Mars: Fourth Order Landscapes• Faces of Other Species, too!

– Flow of younger lava?– The Elephant on Mars – Thanks to Ms. Stoddard– Okay, not a mensa...



• Yardangs:– Erosional æolian features

– Classic sandblasting south of Olympus Mons taken by HRSC (Mars Express) near +6 by 220

– Earth grooved terrain/yardangs (military source: location unknown)



• Yardangs:– Erosional æolian features

– Interesting parallel between Earth yardangs (again some unspecified military source) and Mars yardangs and layered terrain

– The Mars yardangs (top) are from Æolis Mensæ, just south of Elysium on the margins of the southern highlands


Mars: Fourth Order Landscapes• Dunes:

– Depositional æolian features– Classic barchans in Nili

Pateræ, a volcanic depression in Syrtis Major



– Depositional æolian features– Dune field in Endurance Crater

imaged by Opportunity– Closest ridges < ~1 m– Blue color in slacks

between dune crests reflect hæmatite blueberries

– Lighter dust accumulates more on the lip of the crests than on the flanks

– Like Earth star dune fields, probably reflect an unpredictable wind regime, as seen in this mystery military image (below)



– Depositional æolian features– Endurance Crater and its

load of dunes



• Patterned Ground:– Polygons and permafrost

– Mars -72 at 29 (MOC)– Earth NW Territories,

Canada, Sharon Johnson’s GeoImages, UC Berkeley

– Stresses from:– Freeze-thaw of water– Expansion-contraction

of other materials with temperature changes

– Sorting of rock material in the polygon boundaries



• Patterned Ground:– Polygons and permafrost

– Close up of boulders and other larger clasts caught in the boundaries among polygons



• Eskers:– Subglacial streams

– Basal melt feeds streams– Stream beds later exposed

as sinuous, gravelly ridges– Dorsa Argentea, north of

the South Polar Ice Cap Basal Unit, southwest of Hellas, southeast of Argyre



• Mass Wasting:– Landslides

– Common on crater gully walls at a small scale

– Very evident as a major mechanism for the expansion of Valles Marineris– Ganges Chasma– Noctis Labyrinthus



• Mass Wasting:– Landslides

– Common on crater gully walls at a small scale

– Very evident as a major mechanism for the expansion of Valles Marineris– South Candor Chasma



• Mass Wasting:– Chaos

– Collapsed, jumbled terrain– May be source of massive

outflows, possibly explosive if CO2 is involved– Aram Chaos, which

seems to feed into Ares Vallis



• Softened Craters:– Rims eroded

– Burns Ridge (Opportunity)– Floors filled

– Dust and ice (Mars Exp)



• Softened Craters:– Rims eroded possibly by

oceanic currents and processes before the northern lowlands dried out or were resurfaced with younger lavas– Ground penetrating radar

(MARSIS on ESA Mars Express)



• Softened Craters:– Floors filled

– Water – alluvial fans in Eberswalde Crater (below)

– Floors re-excavated by wind– Arabia Terra crater layers

(to right)


Mars: Fourth Order Landscapes• Softened Craters:

– Floors REALLY worked over– Arabia Terra Crater (MOC)

Mars: Fourth Order Landscapes

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