Planetary Geology pdf - NASA

1. The highlands are bright, rugged and heavily
cratered. The plains are dark, flat, smooth and
less cratered.
2. The highlands.
3. The highlands.
4. Younger.
5. Cratered plains and rayed craters.
6. Older than the lunar plains. (Lunar plains are
often called maria.)
7. All three surfaces have craters, although Mars
has the least. Mars has more extensive smooth
plains than the Moon or Mercury; no obvious
volcanoes or canyons are visible on either
Mercury or the Moon. Only Mars shows polar
ice caps.
8. Mars has a dynamic atmosphere (including
dust storms). Gradation by running water
occurred on Mars, but water never flowed on
the Moon. Volcanic activity has been more
extensive on Mars. Tectonism has occurred on
Mars. On the Moon, impact cratering and
plains volcanism have been the major geologic
processes; on Mars, all four major geologic
processes have worked to shape the surface.
9. Younger.
10. The southern region is older.
11. Mars.
12. a. Both are long and relatively narrow. The
canyon on Mars is straight, the one on Venus is
arcuate. [If the student says the Venus canyon
is bright and the Mars canyon is dark, remind
them of the differences in imaging systems:
radar vs. optical camera.]
13. Younger.
14. a. Smooth plains, canyons (deep ocean trenches
and rifts in Africa), volcanoes (represented
by islands) and rough ÒhighlandsÓ (mountain
ranges).
b. Continents, mid-ocean rift/ridge zones.
15. a. Similarities: if EarthÕs continents are thought
of as Òhighlands,Ó both can be divided into
highÐ and low-standing regions; low-lying
regions are relatively smooth. Differences: the
Moon is dominated by craters; lowlands on
the Moon are formed by large impacts flooded
Answer Key
116
by volcanic material; no linear mountain chains
on the Moon; no prominent arcuate ridges or
trenches on the Moon.
b. Students will have difficulty finding any
similarities between Earth and Mercury.
Differences: Mercury is dominated by craters
(impact cratering is the prominent geologic
process); on this image of the Earth, impact
cratering is the only geologic process that is not
apparent.
c. Similarities: both have volcanic and tectonic
landforms. Differences: no continents or midocean
ridge system on Mars, no craters seen on
this global view of Earth.
d. Similarities: both show arcuate mountain
ranges; both show expansive smooth regions;
neither shows very large craters. Differences:
more extreme topography on Earth, continents
and deep ocean basins, compared to more uniform
topographic level on Venus; no midocean
ridge systems on Venus.
16. a. Oldest to youngest: Mercury, Moon, Mars,
Venus, Earth.
b. Answers will vary based on students perception
of Òmost complex.Ó Earth has the most
active geologic history reflected on its surface,
however, some students may argue that Venus is
more complex. Least to most complex: Mercury,
the Moon, Mars, Venus, Earth.
17. (This representation is ~1/3 the size of what
student answer should be.)
Moon Mercury Mars Venus Earth
*18. Answers may vary. In general it is true that the
larger the terrestrial planet, the more complex
its surface. This is not strictly true, however:
the Moon, despite its smaller size, is arguably
more complex than Mercury. Students might
wish to debate the relative complexity of Earth
and Venus, or Venus and Mars, as seen at the
global scale.
Exercise Ten:
Landform Mapping: The Terrestrial Planets
Activities in Planetary Geology for the Physical and Earth Sciences EG-1998-03-109-HQ