Chelsea Esposito Quiz

Chelsea Esposito

1. Internal heat drives geological activity, and Earth retains plenty of internal heat because of its
relatively large size for a terrestrial world. This heat causes mantle convection and keeps Earth’s
lithosphere thin, ensuring active surface geology. It also keeps part of Earth’s core melted, and the
circulation of this molten metal creates Earth’s magnetic field.

2. The four major geological processes are impact cratering, volcanism, tectonics, and erosion. Earth
has experienced many impacts, but most craters have been erased by other processes. We owe the
existence of our atmosphere and oceans to volcanic outgassing. A special brand of tectonics—plate
tectonics—shapes much of Earth’s surface. Ice, water, and wind drive rampant erosion on our planet.

3. The Earth’s atmosphere affects the planet because it creates pressure that determines whether
liquid water can exist on the surface. It absorbs and scatters lights. It creates wind, weather, and
climate. It also interacts with solar win to create a magnetosphere, and can make planetary surfaces
warmer through the greenhouse effect.

4. Both the Moon and Mercury had some volcanism and tectonics when they were young. However,
because of their small sizes, their interiors long ago cooled too much for ongoing geological activity.

5. Dry river channels, rock-strewn floodplains, and eroded craters all show that water once flowed
on Mars, though any periods of rainfall seem to have ended at least 3 billion years ago. Mars today
still has water ice underground and in its polar caps, and could possibly have pockets of underground
liquid water.

6. Mars’s atmosphere must once have been much thicker with a much stronger greenhouse effect,
so change must have occurred due to loss of atmospheric gas. Much of the lost gas probably was
stripped away by the solar wind, which was able to reach the atmosphere as Mars cooled and lost its
magnetic field and protective magnetosphere. Water was probably also lost because ultraviolet light
could break apart water molecules in the atmosphere, and the lightweight hydrogen then escaped to
space.

7. Venus remains geologically active today. Its surface shows evidence of major volcanic or tectonic
activity in the past billion years, and it should retain nearly as much internal heat as Earth. However,
geological activity on Venus differs from that on Earth in at least two key ways: lack of erosion and
lack of plate tectonics.

8. Venus’s extreme surface heat is a result of its thick, carbon dioxide atmosphere, which creates a
very strong greenhouse effect. The reason Venus has such a thick atmosphere is its distance from
the Sun: It was too close to develop liquid oceans like those on Earth, where most of the outgassed
carbon dioxide dissolved in water and became locked away in rock. Thus, the carbon dioxide
remained in the atmosphere, creating the strong greenhouse effect.

9. Unique features of Earth on which we depend for survival are surface liquid water, made possible
by Earth’s moderate temperature, atmospheric oxygen, a product of photosynthetic life, plate
tectonics, driven by internal heat, and climate stability, a result of the carbon dioxide cycle, which in
turn requires plate tectonics.

10. Ozone depletion can leave surface life more vulnerable to dangerous solar ultraviolet radiation,
and the high rate of extinctions could have unknown consequences. The human release of
greenhouse gases into the atmosphere may already be causing global warming and certainly would
affect the climate if it continues.