L.O: THE CRUST USE REFERENCE TABLE PAGE 10

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1 USE REFERENCE TABLE PAGE The oceanic crust is thought to be composed mainly of A) granite B) sandstone C) basalt D) rhyolite 2. To get sample material from the mantle, drilling will be done through the oceanic crust rather than through the continental crust because oceanic crust is A) more dense than continental crust B) softer than continental crust C) thinner than continental crust D) younger than continental crust 3. Base your answer to the following question on the diagram below which represents a cross section of a portion of the Earth's crust. Densities in grams per cubic centimeter are shown for several points. 4. How does the oceanic crust compare to the continental crust? A) The oceanic crust is thinner and contains less B) The oceanic crust is thinner and contains more C) The oceanic crust is thicker and contains less D) The oceanic crust is thicker and contains more 5. Most of the oceanic crust is composed of rock material similar to A) basalt B) granite C) sandstone D) limestone 6. The diagram below represents a cross section of a portion of the Earth's crust. Which inference can best be made from the diagram? A) The Moho is the interface between oceanic and continental crusts. B) The continental crust is thicker than the oceanic crust. C) The continental crust has a higher density than the oceanic crust. D) The Moho is always found at the same depth below the Earth's surface. Which statement about the Earth's crust is best supported by the diagram? A) The oceanic crust is thicker than the mantle. B) The continental crust is thicker than the oceanic crust. C) The continental crust is composed primarily of sedimentary rock. D) The crust is composed of denser rock than the mantle is. 7. Base your answer to the following question on the Earth Science Reference Tables. Compared to continental crust, oceanic crust is A) more mafic and less dense B) more mafic and more dense C) more felsic and less dense D) more felsic and more dense

2 8. Compared to the continental crust, the oceanic crust is A) thicker B) more dense C) more granitic D) more felsic 9. Compared to Earth's oceanic crust, Earth's continental crust is A) thinner and composed of granite B) thinner and composed of basalt C) thicker and composed of granite D) thicker and composed of basalt 10. Compared to continental crust, oceanic crust is A) less dense, more mafic, and thinner B) less dense, more felsic, and thicker C) more dense, more mafic, and thinner D) more dense, more felsic, and thicker L.O: THE CRUST 11. Base your answer to the following question on the map below which shows the locations of deep-sea core drilling sites numbered 1 through 4. The approximate location of the diverging plate at the East Pacific Ridge is shown by a dashed line. Point A is located on the East Pacific Ridge. Compared to the thickness and density of the continental crust of South America, the oceanic crust of the Pacific floor is A) thinner and less dense B) thinner and more dense C) thicker and less dense D) thicker and more dense

3 12. The observed difference in density between continental crust and oceanic crust is most likely due to differences in their A) composition B) thickness C) porosity D) rate of cooling 13. When a continental crustal plate collides with an oceanic crustal plate, the continental crust is forced to move over the oceanic crust. What is the primary reason that the continental crust stays on top of the oceanic crust? A) Continental crust is less dense. B) Continental crust deforms less easily. C) Continental crust melts at higher temperatures. D) Continental crust contains more mafic minerals. 14. Why does the oceanic crust sink beneath the continental crust at a subduction boundary? A) The oceanic crust has a greater density. B) The oceanic crust is pulled downward by Earth's magnetic field. C) The continental crust has a more mafic composition. D) The continental crust is pulled upward by the Moon's gravity. 15. Compared to Earth's continental crust, Earth's oceanic crust is A) thinner and more dense B) thinner and less dense C) thicker and more dense D) thicker and less dense 16. The basaltic bedrock of the oceanic crust is classified as A) felsic, with a density of 2.7 g/cm 3 B) felsic, with a density of 3.0 g/cm 3 C) mafic, with a density of 2.7 g/cm 3 D) mafic, with a density of 3.0 g/cm 3 L.O: THE CRUST

4 17. Base your answer to the following question on the cross section below, which shows the boundary between two lithospheric plates. Point X is a location in the continental lithosphere. The depth below Earth's surface is labeled in kilometers. Compared to the continental crust, the oceanic crust is A) less dense and thinner B) less dense and thicker C) more dense and thinner D) more dense and thicker 18. What is the color and type of rock that forms oceanic crust at mid-ocean ridges? A) light colored and igneous B) light colored and sedimentary C) dark colored and igneous D) dark colored and sedimentary 19. Which mineral is most frequently found in both granitic continental crust and basaltic oceanic crust? A) olivine B) potassium feldspar C) plagioclase feldspar D) quartz

5 20. Base your answer to the following question on the cross section below, which shows the bedrock structure of a portion of the lithosphere. Letters A through D represent locations in the lithosphere. Explain why the oceanic crust subducts beneath the continental crust when the two plates collide. 21. A mineral sample is found to have a density of 3.0 grams per cubic centimeter. It is then broken into two pieces, with one piece twice as large as the other. The smaller of the two pieces will have a density of A) 1.0 g/cm 3 B) 1.5 g/cm 3 C) 3.0 g/cm 3 D) 6.0 g/cm In which part of the Earth are felsic rocks most likely to be found? A) continental crust B) oceanic crust C) plastic mantle D) rigid mantle 23. When two tectonic plates collide, oceanic crust usually subducts beneath continental crust because oceanic crust is primarily composed of igneous rock that has A) low density and is mafic B) low density and is felsic C) high density and is mafic D) high density and is felsic 24. The interface between the crust and mantle of the Earth is generally much deeper under continental surfaces than under ocean surfaces. This information indicates that A) the interface varies in an unpredictable manner B) oceanic crust is thicker than continental crust C) continental crust is thicker than oceanic crust D) both oceanic and continental crusts are approximately the same thickness

6 25. Base your answer to the following question on the block diagram below, which shows a tectonic plate boundary. Compared to the oceanic crust, the continental crust is A) more dense and more mafic B) more dense and more felsic C) less dense and more mafic D) less dense and more felsic 26. Compared to the oceanic crust, the continental crust is A) less dense and more basaltic B) less dense and more felsic C) more dense and more granitic D) more dense and more mafic 27. Compared to the oceanic crust, the continental crust is usually A) thicker, with a less dense granitic composition B) thicker, with a more dense basaltic composition C) thinner, with a less dense granitic composition D) thinner, with a more dense basaltic composition 28. Compared to the average density and composition of oceanic crust, continental crust is A) less dense and more felsic B) less dense and more mafic C) more dense and more felsic D) more dense and more mafic