STEM Earth Science Study Guide Answer Key
Name: _______________________________________ Date: ____________ Hour: _______
Rocks Ch 2
1. Define igneous, metamorphic, and sedimentary rocks.
Igneous rocks are crystalline solids which form directly from the cooling of magma. Igneous
rock is formed through the cooling and solidification of magma or lava.
Metamorphic rock is rock that was once form of rock but has changed to another under the
influence of heat, pressure, or some other agent without passing through a liquid phase
Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's
surface and within bodies of water. Sedimentary rocks are formed on the surface of the Earth,
either in water or on land. They are called secondary, because they often result from the
accumulation of small pieces broken off from pre-existing rocks.
2. How are different types of rocks formed?
Weathering, erosion, cooling, melting, heat and pressure
Sedimentary rock is formed when sediment piles up and forms rock. Metamorphic rock is rock that
changes because of heat and/or pressure. Igneous is cooled lava or magma
3. Where did the igneous rock come from?
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Igneous rock comes from melted rock or magma deep within the Earth.
4. Describe the rock cycle?
It is possible for an igneous rock to become a sedimentary rock by the fact that igneous rock can
be weathered forming sediment for sedimentary rocks.
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5. How does the Earth processes (erosion, mountain building, and glacier movement) are
used to tell the geologic history of the earth?
We can discover geologic history of the earth by looking at the layers of rock and fossils.
6. Define Erosion.
The breakup and removal of rock by moving natural agents (gravity, glaciers, wind, water).
Erosion is the movement of sediment.
7. What are some processes that can shape the landforms.
Wind, water and erosion, deposition, weathering, uplift, continental drift, volcanoes, earthquakes,
tilt, compression, stress fractures,
Fossils Ch 3
8. Define relative dating
Relative dating is the science of determining the relative order of past events the age of an object in
comparison to another.
9. Describe how fossils provide important evidence of how life and environmental
conditions have changed.
By comparing past life with recent life, fossils can help us to understand our current life
and environmental conditions, how evolution occurred and how was the environment
back then.
They provide evidence of existing life such as amber,
Fossils provide important evidence about changes in the natural environment because
paleontologist can study those fossils and study how the environment was back then
compared to now.
10. A fossil of a sea animal was found on top of a mountain. What can a scientist conclude
about the history of that mountain?
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A sea once covered the area
As a scientist was hiking up a mountain, she found fossils of seashells in some of the rocks. The
rocks were formed in an ocean and later uplifted when the mountain was formed.
11. How are rocks and fossils used to understand the age and geological history of the earth
geologic time scale, timelines, relative dating, and rock layers
12. Describe the geological time scale using the chart below. What happened to the primitive
organisms on Earth as the years went by?
life on Earth has changed from primitive organisms to more complex organisms
Plate Tectonics Ch 4
13. How does scientist know that the continents were at one time joined together and then
moved apart?
Continental drift and tectonic plates theory
An example can be Fossils of the fern Glossopteris have been found in Africa, Australia,
Antarctica, and South America. Scientists explain this observation through the theory
14. How are the earthquakes formed?
The movement of tectonic plates, occurs when pressure caused by colliding lithospheric plates
gets extreme and then suddenly releases
15. What is the primary cause of continental drift, earthquakes, and volcanic eruptions?
The primary cause of continental drift, earthquakes, and volcanic eruptions is convection
currents beneath Earth’s crust
16. What are the five physical layers of the Earth? What are the three layers that the Earth is
divided into?
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Lithosphere, mesosphere, asthenosphere, outer core, and inner core.
3 layers: Crust, mantle, and core.
17. What physical layer of the Earth is divided into pieces called tectonic plates?
Lithosphere (outermost)
18. Define Plate Tectonics
Plate tectonics is the theory of tectonic plates.
19. How do the lithospheric plates move centimeters each year?
The lithospheric plates floats on the asthenosphere.
20. What is the difference between Earth’s crust and Earth’s core?
Earth’s core is believed to be . more dense, hotter, and composed of more iron
21. Describe layers of the Earth as a lithosphere (crust and upper mantle), convecting mantle,
and dense metallic core.
lithosphere (crust and upper mantle), convecting mantle (asthenosphere & mesosphere), and
dense metallic core (outer core & the inner core).
22. What layer of the Earth is affected by an Earthquake?
Crust
Compass & Earth’s Magnetic Field
23. How does a compass work using the magnetic field of the Earth?
A compass works using the magnetic field of Earth because the North end of a compass is attracted to
the North Pole
24. How is the direction of the compass needle similar to the direction of the Earth’s
magnetic field?
25. How is a compass used for navigation on land and sea?
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Soil
26. Compare the sizes of different soil samples such as sand, silt, and clay based on their
textures.
27. Describe how soil is a mixture. What is the soil made up of?
Soil is made up of weather eroded rock and decomposed organic material.
28. How are the soils formed?
weathering and growing plant roots
29. What are the minerals in soils made up of?
many tiny pieces of eroded rock,
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