Download There are four empty columns in the table below

AYC12 / EPS C12 / L&S C70U
Spring 2007
Review Sheet for Midterm 2
Nicholas McConnell, GSI
There are four empty columns in the table below. In the top row, list the four major
geological processes discussed in class. In the rows below, write “P” for the terrestrial
bodies that show evidence of each surface process in the past. Additionally, write “N”
for the bodies that are experiencing the processes right now.
Mercury
Impacts
P, N1
Volcanism
P
Venus
P
P, N2
Earth
P
P, N
Moon
P, N1
P
Mars
P
P
Plate Tectonics Erosion
P, N
P, N
P
1
Although large impacts are not nearly as frequent as they were long ago,
micrometeorites still impact bodies with no atmosphere, creating a layer of loose dust.
Alternately, micrometeorite impacts may be thought of as an erosion process.
2
There is no evidence of active volcanism on Venus, but the surface is young enough to
suggest very recent volcanism, which might persist today.
In the top row of these empty columns, list the three major sources of heat for planetary
interiors. Write “P” for the bodies that experienced each heat source in the past and also
“N” for the bodies that are experiencing each heat source right now.
Mercury
Accretion
P
Differentiation
P
Radioactive Decay
P, N4
Venus
P
P3
P, N
Earth
P
P3
P, N
Moon
P
P
P, N4
Mars
P
P
P, N4
3
The Earth and probably Venus slowly continue to differentiate at present, but the
dominant source of heat now is radioactive decay.
4
Although radioactive decay still occurs in the smaller terrestrial bodies, they cool
efficiently and are still relatively inactive.
The first column below lists the four layers of the Earth’s surface and interior.
Phase of Matter: write “S” for each layer that is solid and “L” for each layer that is
liquid.
Material: write “M” for each layer that is metallic and “R” for each layer that is mostly
rock
Density: draw an arrow in the direction of increasing density
Temperature: draw an arrow in the direction of increasing temperature
Miscellaneous: write “B” in the layer responsible for the Earth’s magnetic field. This is
the same layer that cannot propagate S-type seismic waves.
Phase of
Matter
Material
Crust
S
R
Mantle
S
R
Outer Core
L
M
Inner Core
S
M
Density Temperature Miscellaneous
B
The majority of Earth’s mantle is analogous to silly putty, in that it can be slowly
deformed. What other terrestrial bodies is this true for? What is the relationship between
a terrestrial body’s size, its deformability, and its geological activity?
Large bodies cool down less efficiently than small ones, so the largest terrestrial planets,
Earth and Venus, will still have hot, deformable interiors, with a thin, rigid lithosphere.
Smaller bodies--Mercury, Mars, and the Moon--have thicker lithospheres and do not
deform easily. These planets are geologically inactive in the present day, whereas Earth
and Venus display current or very recent goelogical activity.
Describe the cycle by which the ocean floor renews and recycles itself. Where is new
oceanic crust formed, and where does it end up? Why is continental crust generally older
than ocean crust?
Ocean crust is newly produced in mid-ocean ridges, where material emerges from the
mantle. Plate tectonics causes the ocean crust to drift away from the ridges toward
coastlines. When the dense ocean crust reaches light continental crust at a coast, it is
subducted, sinking under the continental crust and back into the mantle. Continental
crust remains on top and so it ages whereas oceanic crust is destroyed and renewed.
Briefly describe some features that show evidence of liquid water previously flowing on
Mars’ surface.
Landslide formations, "teardrop" residue deposits around obstacles, outflow channels,
fan-like delta structures, round pebble-sized "blueberries", . . .
The first column below lists three major regions of the atmosphere (we didn’t distinguish
between the thermosphere and exosphere in class, so they are all lumped together).
Height: Draw an arrow indicating the upwards direction from the Earth’s surface (i.e.
which layer is on the bottom, and which is on top?)
Density: Draw an arrow in the direction of increasing density.
Light Absorption: List the type of light that each layer most predominantly absorbs.
Temperature Change: For each layer, draw an upwards arrow if temperature increases
with height and a downwards arrow if temperature decreases with height. The
stratosphere has two trends: draw one arrow for the upper stratosphere and one for the
lower stratosphere.
Height
Exosphere,
Thermosphere
Density
Light Absorption
Temperature
Change
X Rays
Ultraviolet
Stratosphere
----------------------Infrared
Troposphere
List three greenhouse gases in the Earth’s atmosphere.
Carbon dioxide (CO2), water vapor (H2O), methane (CH4) are the main ones
The evidence that global temperatures are increasing is solid. Describe one positive
feedback mechanism that starts with a global temperature increase.
From An Inconvenient Truth: increased temperatures melt polar ice regions, exposing
water or land, which absorbsrather than reflect sunlight. More sunlight absorbed heats
the Earth more, increasing temperature further.
There are many other examples one could think of.
Describe one negative feedback mechanism that starts with a global temperature increase.
Also from An Inconvenient Truth: seasonal temperature increases cause plant life to
flourish and extract CO2 from the atmosphere. This diminishes the greenhouse effect and
temporarily abates the temperature increase.
Likewise, more examples abound.
What is the relationship between the bands (stripes) in Jupiter and Saturn and the “jet
stream” on Earth, which pushes airplanes and weather patterns from west to east at midlatitudes?
Both features are caused by the Coriolis effect, a result of planetary rotation. Equator-topole air flows are broken up into multiple cells or bands. Jupiter has more bands because
it rotates faster.
Do the giant gaseous planets glow in the infrared? Why?
Yes. Everything that has a non-zero temperature glows at some wavelength. Humans,
Earth, and other terrestrial planets glow in the infrared. The gas giants are somewhat
colder, but still of comparable enough temperatures to glow in IR.
What is the most abundant atom in the outer solar system?
Hydrogen
Name some molecules that are abundant in the giant planets.
Hydrogen (H, H2), helium (He, He2), ammonia (NH3), water (H2O), methane (CH4),
to name the most well-known
Describe the balance that dictates how Jupiter's gaseous body puffs to its present size, not
bigger or smaller. If more mass were added to Jupiter, what would change?
Hydrostatic equilibrium is the balance between outward thermal pressure provided by the
gas and Jupiter's gravity pulling the gas towards its center. If more mass were added to
Jupiter, the gas layers would compress and become more dense, but the overall size
would actually remain the same!
Contrary to the terrestrial bodies, several moons in the outer solar system are geologically
active in spite of being small (compared to Earth, Venus, Mars). What factors contribute
to these moons’ activity?
Moons of the gas giants often undergo sever tidal forces that heat their interiors and give
rise to geological activity. Also, the outer solar system has high abundances of water ice
and other compounds with low melting temperatures. This makes outer solar system
moons more volatile based on their chemical composition.