Download Earth`s internal structure and materials

Physical Geography
Chapter 8 Learning Objectives and Study Questions
1. Describe how the principle of uniformitarianism enables us to interpret Earth’s past in terms of modern
processes and briefly outline the key events in the history of life that delimit major periods in the geologic
time scale.
2. Draw and label a diagram of Earth’s interior that distinguishes the core, mantle, continental crust and
oceanic crust and indicates the density and composition of each.
3. Describe how Earth’s lithosphere differs from its asthenosphere in composition, temperature and strength
(rigidity) and how the asthenosphere facilitates movement of lithospheric plates.
4. Distinguish a mineral from a rock and briefly describe what criteria led to your decision.
5. Infer the source and cooling history of an igneous rock from its color and texture.
6. Classify an igneous intrusion as a dike, sill, pluton or batholith based on its shape, uniformity of composition
and relationships to surrounding rock units.
7. Differentiate clastic, chemically-precipitated and organic sedimentary rocks and briefly describe what type
of material each is derived from.
8. Differentiate between a foliated and a non-foliated metamorphic rock and briefly explain what foliation
indicates about the conditions under which a rock was metamorphosed.
9. Distinguish among key topographic regions of the continents (alpine mountain belts, shields, and platforms)
and ocean basins (continental margins, ridge, trenches, and abyssal plains).
10. Explain how the discovery of seafloor spreading resolved a key difficulty with Wegener’s continental drift
hypothesis.
1. Uniformitarianism enables us to interpret Earth’s past in terms of modern geologic processes because
_____.
A. it’s consistent with religious revelations
B. it seems cool
C. physical laws have remained constant through time
D. scientists say so
E. the rates and intensities of these processes have remained fixed
2. Although there are no rocks this old on Earth, radiometric dating of meteorites suggests Earth formed about
____ ago.
A. 65 million
B. 250 million
C. 540 million
D. 4.56 billion
E. 13.7 billion
3. A major break in the geologic timescale at the end of the Paleozoic, about 250 m.y. ago, is defined by _____.
A. a mass extinction
B. the development of hard parts among animals
C. the first appearance of life on Earth
D. the first evidence of continental crust
E. the formation of an oxygen-rich atmosphere
4. Earth’s density, magnetic field, and the compositions of some meteorites suggest the planet’s core consists
primarily of _____.
A. granite
B. basalt
C. peridotite
D. iron-nickel alloy
E. liquid metallic hydrogen
5. Together, Earth’s crust and the upper rigid part of its mantle comprise the _____.
A. asthenosphere
B. geosphere
C. hydrosphere
D. lithosphere
E. mesosphere
6. Minerals are characterized by all of the following, except _____.
A. always occurring in faceted crystals
B. being naturally-occurring
C. being solid
D. having definite chemical compositions
E. having regular 3-D atomic structure (crystalline structure)
7. _____ are best characterized as aggregates of different minerals grown or cemented together.
A. elements
B. fossils
C. gems
D. mineraloids
E. rocks
8. _____ rocks include all those formed by the solidification of magmas.
A. foliated
B. igneous
C. non-foliated
D. metamorphic
E. sedimentary
9. On the basis of its texture, the igneous rock shown at right likely crystallized
_____.
A. first slowly underground and then rapidly at Earth’s surface
B. rapidly, at or near Earth’s surface
C. rapidly due to fragmentation at Earth’s surface
D. slowly, deep underground
E. very rapidly due to quenching at Earth’s surface
10. On the basis of its color, the magma that formed the igneous rock show at right
likely formed from melting of Earth’s _____.
A. continental crust
B. inner core
C. outer core
D. upper mantle
E. cannot tell from the rock’s color/composition
11. The intrusion shown in the accompanying photo is best described as a _____.
A. dike
B. sill
C. pluton
D. batholith
E. cannot tell from relations shown
12. Based on its texture, the sample shown at right is likely to be a _____ sedimentary
rock.
A. chemically-precipitated
B. clastic
C. organic
D. very old
E. very young
13. Limestone, like the fossil-bearing sample shown at right, is a good example of a
_____ sedimentary rock.
A. chemically-precipitated
B. clastic
C. organic
D. very young
E. very old
14. Of the following sedimentary rocks, _____ is an organic sedimentary rock.
A. chert
B. coal
C. conglomerate
D. limestone
E. shale
15. Metamorphic rocks that recrystallize under stress (directed pressure)
commonly develop_____ textures.
A. clastic
B. coarse-grained
C. foliated
D. glassy
E. non-foliated
16. Metamorphic rocks that recrystallize in response to heat released by the crystallization of nearby magmas
typically have _____ textures.
A. clastic
B. foliated
C. fragmental
D. glassy
E. non-foliated
17. The parts of continents where ancient intrusive and metamorphic rocks
are exposed at the surface are known as _____.
A. alpine mountain belts
B. basins
C. plateaus
D. platforms
E. shields
18. Wegener’s continental drift hypothesis was not widely accepted because it did not _____.
A. account for the splitting of ancient features across continental margins
B. explain the shapes and positions of modern continents
C. include a workable mechanism for moving the continents
D. receive much discussion in the scientific community
E. strike most people as interesting