Introduction to Geology

Introduction to Geology

Quiz 5 - Earth's Structure and Plate Tectonics

1) The rigid outer part of the Earth, consisting of the crust and upper mantle, is a relatively cool, rigid shell and averages about 100 km in thickness and called the:
a. asthenosphere.
b. lithosphere.
c. stratosphere.
d. cryosphere.

Questions 2-10 apply to the Structure of the Earth Diagram below.
Note: the layers on left are classified by composition, layers on the right are classified by physical properties.
Structure of the Earth diagram
Match letters (A to J) to features on the Structure of the Earth diagram.
2) Which letter is the Asthenosphere?
3) Which letter is the Atmosphere?
4) Which letter is the Inner Core?
5) Which letter is the Crust?
6) Which letter is the Lithosphere?
7) Which letter is the Mantle?
8) Which letter is the Mesosphere?
9) Which letter is the Oceans?
10) Which letter is the Outer Core?

11) What is a magnetic field reversal?
a.  when Earth's magnetic field suddenly disappears for short periods of time
b. when Earth's magnetic field suddenly runs east/west instead of south/north 
c. when Earth's magnetic field leaves the south pole and enters the north pole
d. when Earth's magnetic field leaves the north pole and enters the south pole 

12) The alignment of iron-rich minerals in old volcanic lava flows show that:
a. the Earth's magnetic poles may have moved.
b. the Earth's magnetic poles have switched alignment many times in the past.
c. the continents have moved over time.
d. all of the above.

13) What has seismic research revealed about the internal structure of the Earth?
a. There are seismic shadow zones between about 105° to 140° on the opposite side of the globe from a seismic shock.
b. Parts of the Earth are not solid, including the outer core.
c. Earthquakes only occur in the outer rigid lithosphere.
d. all choices are correct.

14) The Mohorovicic discontinuity (or Moho) is:
a. the boundary between granitic continental crust and basaltic oceanic crust.
b. the physical boundary between the Earth's crust and the mantle, existing at depths of about 6–7 miles (10–12 km) under the ocean basins and about 24–30 miles (40–50 km) under the continents.
c. the boundary between earth’s rigid mantle and the liquid core.
d. a fault boundary between two plates in a subduction zone.

15) Isostasy allows continental crust to rise above sea level because it is:
a. denser than ocean crust.
b. is mostly basalt in composition compared with ocean crust.
c. contains more less-dense granitic rocks than ocean crust.
d. all of the above.

16) This extensive region that surrounds the Pacific Ocean basin is both a major earthquake zone and volcano zone.
a. Ring of Volcanoes
b. Ring of Fire
c. Pacific Island Arc
d. The Marianas Trench

17) The theory of continental drift (proposed by Alfred Wegener in 1912) was supported by what kind of evidence?
a. matching fossils on different continents
b. shapes of continents appear to fit like a jigsaw puzzle
c. matching rocks and mountain ranges on different continents
d. all of the above

18) The most conclusive proof for continental drift was provided by:
a. the coastlines of continents on a world map.
b. evidence of sea-floor spreading.
c. identical fossils and rocks found on two separate continents.
d. changes in climatic patterns.

19) The supercontinent in the continental drift hypothesis was called:
a. Panthalassa.
b. Pangaea.
c. Africana.
d. Pandora.

20) Mid-ocean ridges are sites with active volcanism, mild earthquakes, and:
a. consist of rocks of basaltic composition.
b. have thin sediment cover because ocean floor is being newly formed.
c. are locations of hot water vents on the seafloor.
d. all of the above.

21) Geologic mapping shows that bedrock on all continental landmasses around the world range in ages that are exceeding old. However, the oldest rocks found in the world’s ocean basins are:
a. about 2 million years.
b. about 20 million years.
c. about 200 million years.
d. about 2 billion years.
e. none of the above.

22) The theory of plate tectonics helps explain the location of volcanoes and earthquakes. Which of these also describes the current theory of plate tectonics?
a. it combines elements of continental drift and seafloor spreading.
b. it suggests that the lithosphere is divided into pieces, called plates.
c. denser ocean crust sinks below less-dense continental crust along subduction zones.
d. all of the above.

23) In plate tectonics theory, a plate can be made up of:
a. continental lithosphere only.
b. oceanic lithosphere only.
c. both continental and oceanic lithosphere.
d. both continental and oceanic asthenosphere.

23) A mid-ocean ridge is an example of what type of plate boundary?
a. convergent zone
b. divergent zone
c. transform zone
d. subduction zone

25) The youngest rocks on the ocean floor are mostly located near what feature?
a. a mid-ocean ridge
b. a subduction zone
c. an island arc
d. a deep-sea trench

26) A continental rift valley is evidence of which kind of plate boundary?
a. convergent
b. transform
c. divergent
d. uniform

27) At what type of plate boundary are most continental mountains formed?
a. convergent
b. hotspots
c. divergent
d. transform
e. mid-ocean ridges

28) Deep ocean trenches are associated with:
a. ocean ridge systems.
b. transform fault boundaries.
c. subduction zones.
d. rift zones.

29) Almost all deep-focus earthquake occur along or near what type of plate boundary?
a. convergent
b. passive
c. transform
d. divergent

30) What happens when an oceanic plate converges with a continental plate?
a. The denser oceanic plate slides on top of the less dense continental plate.
b. The denser oceanic plate slides under the less dense continental plate.
c. The less dense oceanic plate slides past the denser continental plate.
d. The less dense oceanic plate slides under the denser continental plate.

31) What kind of movement created the Himalayan Mountains?
a. convergence of oceanic crust with continental crust.
b. divergence between two continental crustal plates.
c. transform movement between oceanic and continental crustal plates.
d. convergence of two plates composed of continental crust.

32) Which type of plate boundary is in the southern California region?
a. passive plate boundary
b. divergent plate boundary
c. convergent plate boundary
d. transform plate boundary

Questions 33 to 35 are related to the Plate Boundary Map below.
Plate tectonics map of the world

33) According to the Plate Boundary Map, what type of plate boundary occurs between the North American Plate and the Eurasian Plate?
a. transform boundary
b. divergent boundary
c. convergent oceanic-continental plate boundary
d. convergent oceanic-oceanic plate boundary

34) According to the Plate Boundary Map, what type of boundary occurs between the South American Plate and the Nazca Plate?
a. transform boundary
b. convergent continental-continental plate boundary
c. a convergent oceanic-continental plate boundary
d. convergent oceanic-oceanic plate boundary.

35. According to the Plate Boundary Map, Which of the seven major lithospheric plates consists mostly of oceanic lithosphere?
a. Pacific Plate
b. Antarctic Plate
c. Indy-Australian Plate
d. South American Plate

36) The active volcanoes on Hawaiian Islands and Yellowstone are associated with what type of volcanism?
a. intra-plate volcanism at a hot spot
b. subduction zone volcanism
c. volcanism at a divergent plate boundary
d. volcanism at a convergent plate boundary

37) Gravitational heat convection is the primary mechanism of plate tectonic activity. However plate motion is also influenced by the formation of the lithosphere. What forces drive plate motion?
a. slab-pull as the mantle flows beneath the rigid lithosphere.
b. slab-suction as old, cold ocean crust sinks into the mantle, pulling crustal rocks and seafloor sediments along with it.
c. ridge-push from the weight of new crust rising above the seafloor along mid ocean ridges, pushing older, cooler crust away.
d. all choices are correct.

38) What is the process by which material is added to a tectonic plate or a landmass over time?
a. accretion
b. terrane
c. craton
d. shield

39) The great supercontinent Pangaea first assembled by plate convergence as the proto-Atlantic (the ancient Iapetus Ocean) closed around 300 million years ago. What was the name of the ancient global ocean that existed when all the ancient continents were assembled together?
a. Panthlassa
b. Gondwanaland
c. Laurasia
c. Tethys Seaway

40) California's newest national park is Pinnacles National Park near Monterey, CA. The park encompasses of the Pinnacles Formation, a volcanic rock formation comprising half of the ancient Pinnacles Volcano on the western side of the San Andreas Fault. The volcano originally formed along the San Andreas Fault in the vicinity of Los Angeles as it started forming about 23 million years ago. Where is the other half of the original volcano?
a. It is now taking a vacation in northern California.
b. It got subducted along with the Farollon Plate.
c. It migrated down to Baja California.
d. It still exists as the Neenach Formation near where it formed near Los Angeles, but on the eastern side of the San Andreas Fault.