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Mars: Third Order Landscapes

Mars: Third Order Landscapes. Geography 494-01 S/07 Dr. Christine M. Rodrigue. Mars: Third Order Landscapes. The “Orders of Relief” for Martian Landscapes The first order was the great crustal dichotomy: Northern lowlands: ~ 1/3 Southern highlands: ~2/3

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Mars: Third Order Landscapes

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  1. Mars: Third Order Landscapes Geography 494-01 S/07 Dr. Christine M. Rodrigue C.M. Rodrigue, 2007 Geography, CSULB

  2. Mars: Third Order Landscapes • The “Orders of Relief” for Martian Landscapes • The first order was the great crustal dichotomy: • Northern lowlands: ~ 1/3 • Southern highlands: ~2/3 • The second order is tonight’s focus: • Tharsis and Elysium rises • The largest craters: Hellas, Argyre, Isidis, Utopia • Valles Marineris • The polar ice caps C.M. Rodrigue, 2007 Geography, CSULB

  3. Mars: Third Order Landscapes • The “Orders of Relief” for Martian Landscapes • The third order is in order now: • 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 C.M. Rodrigue, 2007 Geography, CSULB

  4. Mars: Third Order Landscapes • The “Orders of Relief” for Martian Landscapes • The third order is “in order” now: • The three eras and their namesakes: • Noachian Era is named for Noachis Terra, one of the oldest terrains on Mars • The Hesperian Era is named for Hesperia Planum • The Amazonian Era is named for the smooth Amazonis Planitia • These three regions are subregions of the northern lowlands and the southern highlands at or smaller in scale and less conspicuous than such features as Utopia Planitia, Valles Marineris, the northern ice cap, or the Tharsis rise C.M. Rodrigue, 2007 Geography, CSULB

  5. Mars: Third Order Landscapes • The “Orders of Relief” for Martian Landscapes • The third order is “in order” now: • So, the third order of relief is actually rather a vague level spatially (at or somewhat smaller than the second order of relief) but a clear, if contested, temporal concept • I needed to talk about these eras and decided to use their regional namesakes to give them a “place” in the class • If I were a geologist instead of a geographer, I might have organized the class temporally, as a kind of historical narrative, with regions the incidental side effect of the discussion • With that caveat… C.M. Rodrigue, 2007 Geography, CSULB

  6. Mars: Third Order Landscapes • Debates over Era Lengths C.M. Rodrigue, 2007 Geography, CSULB

  7. Mars: Third Order Landscapes • Noachis Terra C.M. Rodrigue, 2007 Geography, CSULB

  8. Mars: Third Order Landscapes • Noachian Era • Oldest: • ~4.6 – 3.8 or 3.9 billion BP (or is it 3.5 billion?) • Earliest accretion, melting, differentiation of the planet • Era of bombardment (Earth’s Hadean times) • Intensely cratered with wide range of crater sizes • Some geomorphic erosion of craters • Establishment of and shutting down of planetary magnetic field • Some geological activity: • Valley networks • Volcanic activity (low viscosity flows, small pateræ) • Oceans? • Examples: • Noachis Terra • Arabia Terra • Terra Sirenum C.M. Rodrigue, 2007 Geography, CSULB

  9. Mars: Third Order Landscapes • Hesperia Planum C.M. Rodrigue, 2007 Geography, CSULB

  10. Mars: Third Order Landscapes • Hesperian Era • Intermediate ages: • Most commonly from ~3.8 – 2.9 billion BP (or even 1.8 billion BP) • Era in which the bulk of Tharsis and Elysium rises developed • Intense geological activity: • Shield vulcanism • Folding • Faulting and formation of linear grabens in extensional zones • Gigantic outwash floods far past Noachian valley networks • Era in which climate dried out, dustiness, water evaporating, freezing, sinking into permafrost • Examples: • Hesperia Planum • Terra Tyrrhena • Aonia Terra • Margaritifer Terra C.M. Rodrigue, 2007 Geography, CSULB

  11. Mars: Third Order Landscapes • Amazonis Planitia C.M. Rodrigue, 2007 Geography, CSULB

  12. Mars: Third Order Landscapes • Amazonian Era • Youngest: • Most commonly from ~3.8 – 2.9 billion BP (or even 1.8 billion BP) to present • Much more peaceful geologically: • Some vulcanism • Some subsurface water releases and gullying • Some meteoroids continue to smack down • May even be obliquity-related ice ages • Extent and recency of these energetically debated • Examples: • Amazonia Planitia • Utopia Planitia • Chryse Planitia • Acidalia Planitia C.M. Rodrigue, 2007 Geography, CSULB

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