Earth Science Study Guide
Answer the following questions on a separate sheet of paper.
1. What are the 4 layers of the Earth (in order from outermost to innermost)?
Crust, mantle, outer core, inner core
2. Which is the thickest (largest) layer of the Earth?
Mantle
3. The inner core of the Earth is (circle one): solid, liquid, gas
4. Define the following terms:
a. Lithosphere – crust and outer solid part of the mantle
b. Asthenosphere – taffy-like layer that lithospheric plates move on
c. Oceanic plate – denser, thinner tectonic plate
d. Continental plate – thicker, less dense tectonic plate
e. Convergent – moving together
f. Divergent – moving apart
g. Transform – moving side by side/opposite directions
h. Subduction – denser plate sinks under the less dense one, melting as it gets to the
asthenosphere. Happens at convergent boundaries
i. Convection current – “warm magma rises, cool magma sinks.” Circular motion inside the mantle
that drives continental drift
j. Tectonic plate – piece of the lithosphere that can “move” with convection currents
5. The theory that all continents moved from a single, large supercontinent is called what? What is the
supercontinent called?
Theory of continental drift, Pangaea
6. For each formation, tell what plates are involved and at what boundary/boundaries:
a. Mid-ocean ridge – oceanic/oceanic, divergent
b. Rift valley – continental/continental, divergent
c. Mountain – continental/continental, convergent
d. Volcano – continental/continental (div.), oceanic/oceanic (conv.), oceanic/continental (conv.)
e. Earthquake – nearly all boundaries (plate movement causes faults)
7. As seafloor spreading occurs, stripes appear in the new seafloor based on the direction that iron
particles are pointing. The same cause is the reason a compass points north. What is this cause?
Earth’s magnetic field
8. What are earthquakes? What causes them? Where do they occur?
Cracks in the crust (faults) build up energy. When that energy is released, it leaves in the form of
seismic waves (earthquake). They occur at boundaries and faults.
9. What are seismic waves? Compare and contrast primary and secondary waves.
Seismic waves are energy released during an earthquake. Primary waves hit first, travel in a straight
line (compression wave), and are less damaging to structures. Secondary waves hit second, travel in
an up and down motion, and are more damaging to buildings.
10. What does a seismograph measure? What is magnitude?
Magnitude, measure of the energy released during an earthquake
11. What does the Richter scale measure? What does the modified Mercalli scale measure?
Magnitude from 1.0 – 10.0, damage from I – XII (1-12)
12. What are two reasons why a 7.2M earthquake might cause less damage than a 5.1 earthquake?
Location (ocean, distance from cities), depth (deeper = less damage), readiness by impacted cities,
etc.
13. Compare and contrast focus and epicenter.
Focus – point inside earth where earthquake begins
Epicenter – point directly above focus where earthquake hits hardest
14. What is a tsunami? What causes tsunamis?
Seismic wave of water caused by a 7.5 M (or higher) earthquake underwater
15. Composite volcanoes (stratovolcanoes): where are they formed? What size and shape are they?
How do they erupt? What do they erupt? What is their lava made of?
Convergent subduction zones, medium/cone-shaped, explosive eruption of silica-based lava (thick)
and tephra
16. Shield volcanoes: where are they formed? What size and shape are they? How do they erupt?
What do they erupt? What is their lava made of?
Divergent boundaries and hot spots, large/dome-shaped, less active eruption of iron-andmagnesium-based lava (runny)
17. Cinder cone volcanoes: what size and shape are they? How do they erupt? What do they erupt?
Smallest/cone-shaped, bursts of gas and ash
18. Compare and contrast lava flow that is rich in silica with lava low in silica. How does the presence of
silica change how the lava flows? Where does the silica come from? How does the silica get in the
magma?
Silica-rich lava (from the melting of crust) is thick and sticky. Iron and magnesium lavas (from the
mantle) are thin and runny.
19. How does how the lava flows affect the shape and size of each type of volcano? For example, a
composite volcano is steep sloped. Why?
Sticky lava doesn’t flow very far, so the base is narrow and the volcano is taller (cone shaped). Thin,
runny lava spreads out wide distances, giving a broad base with a gentle slope (dome shaped).
20. Why can volcanoes occur at convergent and divergent boundaries, but not at transform boundaries?
No access to magma
21. What is the force that moves tectonic plates?
Convection currents
22. Lava from volcanoes moves slowly enough for people to get away from it. What are three reasons
why volcanic eruptions are still dangerous?
Property damage, fire, mudslides, flooding, tephra, falling timber, etc.
23. When does a volcano become extinct, which means that it will never erupt again?
After many years of inactivity (~10,000 years)
24. What are the 3 different classes of rocks?
igneous, metamorphic, sedimentary
25. What processes are responsible for breaking larger rocks into smaller pieces (sediment)?
Weathering and erosion
26. What processes are responsible for creating sedimentary rocks from sediment?
Compacting and cementing
27. What are igneous rocks called if they form above the Earth? Inside?
Extrusive, intrusive
28. Indiana is well known for its vast deposits of this sedimentary stone, found in lakebeds, that
contributes to southern Indiana’s vast network of caves.
Limestone
29. What information can we gain from fossils?
How, when, and where the organism lived
30. Are the following objects fossils? If so, write “fossil” and a brief reason why. If not, write “no” and a
brief reason why not.
a. Pottery piece found in an ancient city – no, not “living”
b. Casting (mold) of an ancient fish in rock – yes, imprint
c. Dog prints in mud – no, not old or long lasting
d. Dinosaur tracks in rock – yes, trace
e. Small, extinct mammal preserved in glacial ice – yes, remains
31. Which layer is the oldest? Rank the fossils in age from youngest to oldest.
A, B, C, D, E
32. The Earth has been around for approximately 4.6 billion years. Within that space, time is split into
large and small chunks. Order the chunks in order from largest to smallest: period, age, eon,
epoch, era
Eon, era, period, epoch, age
33. Define the following terms:
a. Glacier – massive chunk of ice that moves under its own weight
b. Cave – underground empty space from the weathering of rock
c. Sinkhole - hole in the ground formed by the collapse of the surface layer
34. Explain the topographical (landscape) differences in northern and southern Indiana. How did
glaciers affect these changes?
Northern Indiana is flat. Southern Indiana is hilly and cavernous (lots of caves). Glaciers flattened
land as they moved south, then melted. The water cut deeper valleys and penetrated the
limestone, forming caves.
35. What is soil? How is soil made?
Soil is a mixture of sediment, organic matter, air, and water. Soil development depends on 4
factors: rock type, climate, topography, and living things. These work together to break down
parent rock into smaller and smaller pieces.
36. Soil can be developed or undeveloped. List 4 factors that speed up or slow down soil development.
Soil development depends on 4 factors: rock type, climate, topography, and living things.
37. What is a soil profile? How is this different from a soil horizon?
Soil profile is a vertical section of the soil layers. A horizon is one of these layers.
38. Which horizon contains the most humus?
A horizon (topsoil)
39. Which layer is most responsible for the makeup of the soil?
Parent rock
40. Soil texture comes in 3 sizes. List them and explain which will drain water the best.
Sand, silt, and clay – sand drains the best because its grains are the largest, leaving spaces for water.