Earth Systems – Unit 5 Study Guide (sedimentary rocks, metamorphic rocks, fossils)
ANSWER KEY
Vocabulary Review: Define the following terms.
1. sediment
Fragments of rock that have been broken down as a result of weathering.
2. weathering
The process by which rocks are broken down via wind, water, ice, or through the actions of living things.
3. erosion
The removal and transport, via wind and water, of sediments (soil and rock) from one location to another.
4. deposition
The process by which sediments, soil, and rocks are added to a landform/landmass. (Where they end up via
erosion.)
5. lithification
The physical and chemical processes that turn sediments into rock.
6. compaction
The movement of sediment grains closer to one another (squeezing together) due to the weight forces of
overlying sediments.
7. cementation
The hardening and gluing together of sediments by the precipitation of minerals in the pore spaces between
sediment grains.
8. bedding
The formation of divisional planes within the rock that separates different layers.
9. metamorphism
The change in minerals (form) due to extreme temperature and pressure (without melting the rock).
10. foliation
Repetitive layering in metamorphic rock. (Typically results in banding through the rock due to folding of
sedimentary beds or alignment of crystals due to uneven pressures applied to igneous or sedimentary rock.)
11. fossils
The remains of a once living orgamism.
12. molds
Impression left behind in the sediment where a plant, animal, or shell once was.
13. casts
Impression that has been filled in with other sediment. (Filled in molds.)
14. petrification
The process by which organic material is converted into stone through the replacement of the original
material and the spaces between them with minerals. (aka mineralization)
15. whole body fossils
Preservation of an entire plant or animal.
16. trace fossils
Any imprint or mark left by an organism. Typically provide evidence for an animal’s behavior or the way in
which they lived.
17. coprolites
Fossilized animal feces.
Concept Review: Use your notes and video handout to complete the following.
18. List the different agents of erosion.
Wind, moving water, gravity, glaciers
19. Be able to draw and explain the rock cycle.
See last unit (review) and powerpoints
20. Describe/explain the process of lithification.
2 parts: compaction and cementation (see definitions above)
21. What are the 2 basic types of bedding and how are they different?
Graded bedding = bedding characterized by heavier and coarser particles located near the bottom of the rock
and lighter, fine particles located at or near the top
Cross-bedding = inclined layers of sediment deposited along a horizontal surface (the tilting is a result of
depositional layering, not post-depositional deformation)
22. List the 3 types of sedimentary rocks, explain how they form, and what typical (types of) rocks are formed.
Clastic = Formed through the lithification of sediments. Based on grain size.
Coarse grained (composed of pebbles/gravel) typically breccia or conglomerate;
Medium grained (composed of sand) typically sandstone;
Fine grained (composed of silt or clay) typically siltstone or shale
Organic = Composed of once living plant or animal remains or a chemical activity from them.
Chemical = Physical or chemical formation due to the precipitation of minerals from solution (precipitation of
minerals out of a saturated solution or evaporation of water leaving minerals behind)
23. Explain why sedimentary rocks typically forms at or near the Earth’s surface.
Erosion and weathering are processes associated with the Earth’s surface and are necessary for most
sedimentary rock formation. Deposition, compaction and cementation typically occur at or near the surface
also and water is necessary for the process of cementation.
24. List and describe the agents of metamorphism (rocks).
Heat – necessary to break chemical bonds (which is necessary for the formation of new minerals)
Pressure – necessary to create denser minerals with more compact crystalline structures (making them stronger)
25. Compare and contrast the 2 textural groups for metamorphic rocks.
Foliated – typically consist of visible layers and bands (see definition above)
Nonfoliated – typically consist of blocky crystal shapes
26. Compare and contrast the 3 types of metamorphic rocks (how they are formed).
Regional – affects rocks over an extensive are/region as a result of large-scale action of heat and pressure
(such as from two converging tectonic plates)
Contact – due to contact or proximity to an igneous intrusion (contact with magma)
Hydrothermal – due to the interaction of rock with very high temperature water with variable mineral
composition (that causes chemical reactions to occur and alter the existing rock)
27. Explain why metamorphic rocks form underground.
Due to necessity of extreme heat and pressures
28. Explain what fossils can tell us from a geological perspective.
Provide evidence about the history of life on Earth.
Shows how organisms have changed over time (which lived when, which flourished, etc.)
Provides evidence for evolution.
Also tells the “story” about the rocks themselves, the organisms that lived, and the events that took place at
different times throughout the Earth’s history.
29. Compare and contrast the different types of fossils.
See definitions for each above…
Mold = impression left behind
Cast = filled in impression
Petrification = mineralized organic material
Whole body preservation = preserved organism (in amber, tar, quicksand, ice, etc.)
Trace fossils = any mark showing an animal’s behavior (footprints, trackways, coprolites, etc.)