Universe Eighth Edition

1. Roger A. Freedman • William J. Kaufmann III Universe Eighth Edition CHAPTER 9 The Living Earth

3. HW – Read Chapter 10, 11Online Quizzes for Chapters 9,10, and 11 due Monday 10/18Exam 2 – Scheduled for Monday 10/25(will cover Chapters 7-15)

10. The Earth shows very little evidence of meteor impacts because • plate tectonics is continuously recycling the Earth’s crust. • wind and rain have continually eroded the Earth’s surface. • very few meteors struck the Earth in the past. • vegetation has covered the craters. • Both A and B are correct. Q9.11

11. The Earth shows very little evidence of meteor impacts because • plate tectonics is continuously recycling the Earth’s crust. • wind and rain have continually eroded the Earth’s surface. • very few meteors struck the Earth in the past. • vegetation has covered the craters. • Both A and B are correct. A9.11

16. In the greenhouse effect, • some infrared radiation emitted by the Earth’s surface is absorbed by the atmosphere. • some ultraviolet radiation emitted by the Earth’s surface is absorbed by the atmosphere. • vegetation traps thermal energy near the surface. • infrared radiation from the Sun is captured as it enters the Earth’s atmosphere. • infrared radiation from the Sun is reflected by the Earth’s atmosphere into space. Q9.4

17. In the greenhouse effect, • some infrared radiation emitted by the Earth’s surface is absorbed by the atmosphere. • some ultraviolet radiation emitted by the Earth’s surface is absorbed by the atmosphere. • vegetation traps thermal energy near the surface. • infrared radiation from the Sun is captured as it enters the Earth’s atmosphere. • infrared radiation from the Sun is reflected by the Earth’s atmosphere into space. A9.4

27. Which of the following is a correct statement about seismic waves used to map the Earth’s interior structure? • P waves are longitudinal and are able to travel through solids and liquids; S waves are transverse and can only travel through liquids. • P waves are transverse and are able to travel through solids and liquids; S waves are longitudinal and can only travel through liquids. • P waves are transverse and are able to travel through solids and liquids; S waves are longitudinal and can only travel through solids. • P waves are longitudinal and are able to travel through solids and liquids; S waves are transverse and can only travel through solids. Q9.7

28. Which of the following is a correct statement about seismic waves used to map the Earth’s interior structure? • P waves are longitudinal and are able to travel through solids and liquids; S waves are transverse and can only travel through liquids. • P waves are transverse and are able to travel through solids and liquids; S waves are longitudinal and can only travel through liquids. • P waves are transverse and are able to travel through solids and liquids; S waves are longitudinal and can only travel through solids. • P waves are longitudinal and are able to travel through solids and liquids; S waves are transverse and can only travel through solids. A9.7

35. The Earth’s magnetic field is generated by • electric currents in the liquid outer core; the field has never changed direction. • electric currents in the liquid inner core; the field has never changed direction. • electric currents in the liquid outer core; the field has reversed many times in the past. • electric currents in the liquid inner core; the field has reversed many times in the past. • electric currents caused by interactions with the solar wind. Q9.8

36. The Earth’s magnetic field is generated by • electric currents in the liquid outer core; the field has never changed direction. • electric currents in the liquid inner core; the field has never changed direction. • electric currents in the liquid outer core; the field has reversed many times in the past. • electric currents in the liquid inner core; the field has reversed many times in the past. • electric currents caused by interactions with the solar wind. A9.8

40. The oxygen in our atmosphere is chemically reactive, combining with other elements to form compounds, and is also being used by respiratory life. Despite this, the amount of oxygen in our atmosphere is not decreasing because it is being replenished by • outgassing from seawater. • volcanic eruptions. • biological activity, such as photosynthesis. • meteors and comets, which bring oxygen to the Earth. • solar radiation breaking down CO2. Q9.14

41. The oxygen in our atmosphere is chemically reactive, combining with other elements to form compounds, and is also being used by respiratory life. Despite this, the amount of oxygen in our atmosphere is not decreasing because it is being replenished by • outgassing from seawater. • volcanic eruptions. • biological activity, such as photosynthesis. • meteors and comets, which bring oxygen to the Earth. • solar radiation breaking down CO2. A9.14

48. Key Ideas • The Earth’s Energy Sources: All activity in the Earth’s atmosphere, oceans, and surface is powered by three sources of energy. • Solar energy is the energy source for the atmosphere. In the greenhouse effect, some of this energy is trapped by infrared absorbing gases in the atmosphere, raising the Earth’s surface temperature. • Tidal forces from the Moon and Sun help to power the motion of the oceans. • The internal heat of the Earth is the energy source for geologic activity.

49. Key Ideas • The Earth’s Interior: Studies of seismic waves (vibrations produced by earthquakes) show that the Earth has a small, solid inner core surrounded by a liquid outer core. The outer core is surrounded by the dense mantle, which in turn is surrounded by the thin low-density crust. • Seismologists deduce the Earth’s interior structure by studying how longitudinal P waves and transverse S waves travel through the Earth’s interior. • The Earth’s inner and outer cores are composed of almost pure iron with some nickel mixed in. The mantle is composed of iron rich minerals. • Both temperature and pressure steadily increase with depth inside the Earth.

50. Key Ideas • Plate Tectonics: The Earth’s crust and a small part of its upper mantle form a rigid layer called the lithosphere. The lithosphere is divided into huge plates that move about over the plastic layer called the asthenosphere in the upper mantle. • Plate tectonics, or movement of the plates, is driven by convection within the asthenosphere. Molten material wells up at oceanic rifts, producing seafloor spreading, and is returned to the asthenosphere in subduction zones. As one end of a plate is subducted back into the asthenosphere, it helps to pull the rest of the plate along.