Metamorphic Rocks and Resources WB Key

Answers to Section T: Comparative Planetology 1. 2. Propose and defend criteria that help divide the planets into two groups: the inner planets (Mercury, Venus, Earth, Mars) and the outer planets. Inner Planets also known as Terrestrial planets Mercury, Venus, Earth, Mars. Small, solid spheres. Higher average density than outer planets. Closer to the sun. Contain large proportions of silicate material. Outer Planets also known as Jovian planets Jupiter, Saturn, Uranus, Neptune. Large gas giants. Less dense than inner planets. Further away from the sun. Contain large quantities of gas. Relate the densities, compositions, and spacing of the planets to their formation, according to the nebular model for the origin of the solar system. A nebula of gas and dust collapsed due to gravity to form the sun, 9 planets, moons, comets and asteroids. The dust and gas all revolved around the sun in the same direction in the same plane, thus produced a group of planets that revolve around the sun in the same direction in the same plane. The sun was able to burn off the lighter, gaseous material of the nearby planets to leave a solid rocky core. The outer planets were too far from the sun to have their thick hydrogen atmospheres to be burned off. The outer planets have a higher proportion of lower-temperature materials, those material that condense at lower temperatures, such as hydrogen and helium. The inner planets have a higher proportion of higher-temperature materials, those materials that condense at higher temperatures, such as silicate minerals 3. Compare and contrast the following characteristics of Earth with the other inner planets and Earth's moon: atmosphere, surface features, internal structures, magnetism, and cratering. Surface Internal Atmosphere Cratering Magnetism Features Structures Trace Rocky surface Large iron core Heavily cratered Weak magnetic field Venus Very thick runaway greenhouse effect Rolling plains. Lava flows responsible for numerous resurfacing Large core Tectonic activity Few crater sites No significant magnetic field Earth N2, O2, H2O vapour Mountains, rivers, lots of erosion Core, mantle, crust, tectonic plates Few crater sites Strong magnetic field Moon None Some mountains, ancient lava flows called maria Core, a few small moonquakes Heavily cratered no substantial magnetic field Mars Very thin Evidence of ancient rivers. Mountains Core, limited tectonic activity Some craters but erosion removes evidence Lacks a significant magnetic field Mercury -9- Answers to Unit 5 Workbook Metamorphic Rocks and Resources 4. Determine the geologic history of a planet or Earth's moon, using relative age dating techniques There are two major theories concerning the origin of the moon. 1) A solid rocky planet formed along with others and was either captured by the Earth or formed in orbit. 2) An ancient massive collision with the Earth resulted in a lot of material shot into space that coalesced to form the moon. The major surface features of he present moon include the ancient highlands and the lower darker regions called maria. The composition of the highlands includes anorthosite and breccia. The composition of the maria is basalt. The maria must be younger than the highlands because there are fewer craters. 5. Describe the evidence discovered on Mars that indicates water once flowed. There are stream-like channels, and braided channels that could only have been formed by water flowing across the surface. The evidence from cratering indicates that these stream channels must be ancient. A very thin atmosphere may have allowed the water to vapourize. 6. Why is it so hot on the surface of Venus? The atmosphere is very thick and is comprised of 95% CO2. This greenhouse gas traps all the heat. 7. The feature that all of the planets have in common is a) their average density. b) their surface temperature. c) the number of moons orbiting each. d) the direction of revolution around the sun. 8. The surface of Mars shows evidence of running water. Which of the following is least likely to be found on Mars? Coal is organic in origin. There is a) Coal no indication that life has ever b) Shale existed on Mars. c) Sandstone d) Conglomerate Use the following sketch of a section of the moon’s surface, which shows a variety of geological features, to answer question 9 9. The most likely order of ages of the moon’s geological features, from oldest to youngest, is a) V, Z, Y, X, W Y impact crater cuts across Z; V b) V, Y, W, Z, X lava flow has filled Y; X cuts c) Z, Y, V, X, W across V; and W cuts across X d) Z, V, Y, W, X 10. The most heavily cratered solid bodies in the solar system also have the Because there are no lava a) deepest oceans. b) thickest atmospheres. flows to cover up meteorite c) least tectonic activity. d) highest internal temperatures. impacts. 11. Which of the following solar system bodies shows evidence of flowing water at some time in its history? a) Mars b) Moon c) Venus d) Jupiter - 10 - Answers to Unit 5 Workbook Metamorphic Rocks and Resources 12. The Nebular Model of the origin of the solar system suggests that the outer planets consist of lighter, easily evaporated materials because these materials would condense where a) pressures were lower. The four inner planets lost their b) pressures were higher. c) temperatures were lower. d) temperatures were higher. atmospheres of hydrogen and helium the sun wasthe close enough to boil 13. All of the following may be used as criteriabecause for distinguishing inner planets from the outer planets except All planets revolve in the same direction a) size. b) density. around the sun, counter-clockwise, as seen c) orbital period. d) orbital direction. from above. 14. Which of the following is best explained by the Nebular Hypothesis of the solar system’s formation? a) Some planets do not have an atmosphere. b) Most planets have cooler surface temperatures than Earth. c) Some outer planets have higher internal temperatures than inner planets. d) Inner planets have rocky compositions, outer planets have gaseous compositions. 15. The best reason for a lack of cratering on Venus, is that Venus has a(n) a) acidic atmosphere. b) weak magnetic field. c) variety of active geologic processes. d) weaker gravitational pull than Earth. 16. According to the Nebular Model of solar system formation, the planets should all have similar a) densities b) number of moons c) surface temperatures d) direction of revolution 17. The rock type which makes up the dark areas of the moon’s surface is a) shale b) basalt c) gabbro d) limestone 18. The moon has many more small craters than the Earth because the moon has a) a solid core b) more active volcanoes c) no significant atmosphere d) a weaker gravitational field 19. Venus and Mercury both have a) dense atmospheres b) weak magnetic fields c) similar equatorial radii d) heavy impact cratering 20. The Solar System body that has many presently active volcanoes is a) Mars b) Mercury c) Earth’s moon d) Jupiter’s moon, Io - 11 - Answers to Unit 5 Workbook Metamorphic Rocks and Resources 21. Virtually all of the faults on the moon are of the “normal type”. The presence of normal faults indicates that the moon may have been subjected to a) shear during plate sliding b) uplift during meteorite impacts c) tensions during crustal shrinking d) compression during plate collision 22. A liquid core in a rocky planet is most likely to produce a) craters b) erosion c) sudduction d) a magnetic field Use the following sketch to answer questions 23 to 24 The sketch was produced using photographs taken by the Mars Viking orbiter and shows a section of the 50 km wide, Valles Marineris canyon. The rock layer composing the canyon rim to be basalt. 23. The main surface process which is evident in the area of Mars shown in the sketch above is a) river erosion b) wind erosion c) mass wasting d) glacial erosion 24. From oldest to youngest, the correct order of formation of the features listed in the box is a) crater, flow X, basalt, flow Y  Canyon rim basalt b) flow Y, flow X, crater, basalt  Debris flow X c) flow X, basalt, crater, flow Y  Large crater d) basalt, crater, flow X, flow Y  Debris flow Y 25. Which planet in the solar system has icecaps, volcanoes, and canyons? a) Mars b) Venus c) Jupiter d) Mercury 26. The red-orange colour of the soil on Mars indicates the presence of a) ice b) iron c) bacteria d) nitrogen 27. Which of the following is not known to occur on the surface of Mars? a) Sand dunes Algal reefs are organic. b) Algal reefs c) Steam channels d) Shield volcanoes 28. Which of the following rock types would least likely be found on the Moon’s surface? a) Basalt Limestone is formed b) Breccia c) Limestone by organic processes. d) Anorthosite - 12 - Answers to Unit 5 Workbook Metamorphic Rocks and Resources 29. The best reason for grouping the planets Jupiter, Saturn, Uranus, and Neptune together is that they a) are the closest to the sun b) have Galilean moons c) have rocky crusts and iron cores. d) have similar densities and compositions 30. The light-coloured lunar highlands a) are made of flood basalts b) represent original crustal material. c) have not been affected by meteorite impacts d) consist of chemically weathered sedimentary rock 31. Which of the following are unlikely to occur on the moon? a) Sand dunes To form sand granite must be worn down to fine b) Basalt maria particles. Also, there is no wind and atmosphere to c) Impact craters form a dune. d) Seismic activity 32. Which of the following best describes the surface of Mercury? a) It is similar to the moon’s surface b) It is hotter than Venus c) It has fewer craters than Mars d) It is similar to the surface of Jupiter 33. Which of the following are not associated with Mars? a) Volcanoes b) Rift valleys c) Sand dunes d) Fold mountains 34. Describe three characteristics of the planets of our solar system, other than distance from the sun, that justify their classification into inner and outer groups. As there is some question at this time whether Pluto is a planet, omit Pluto from your answer. 1. 2. 3 CHARACTERISTIC INNER PLANETS OUTER PLANETS Example: Distance from the sun. Four inner planets are closer to the sun. Outer planets are farther away from the sun than inner planets are. Equatorial radius Inner planets are small (2 440 km to 12 700 km). Outer planets are much larger (24 000 km to 71 400 km) Inner planets are small (0.0558 to 1 – relative to the Earth). Outer planets are very large (14.54 to 318 times the Earth’s mass). Inner planets have a high density (3.94 g/cm3– 5.520 g/cm3) Outer planets have a low density (0.69 g/cm3– 1.31 g/cm3) Mass Density - 13 - Answers to Unit 5 Workbook Metamorphic Rocks and Resources 4 5 6 7 8 9 10. Number of moons Inner planets have very few moons (0 to 2). Outer planets have many moons. Inner planets are closely spaced. Outer planets are widely spaced. Inner planets don’t have any rings. Outer planets have rings. Inner planets are rocky. Outer planets are gaseous. Inner planets have temperatures above -23° C. (except Mercury at night) Outer planets have temperatures below -150° C. Gravitational field strength Weak Strong Orbital period Short Long Planetary spacing Presence of rings Composition Surface temperature 35. a) Density can be used to divide the planets into two groups: the inner and outer planets. What difference in composition would account for the difference in density of the two groups? The inner planets are rocky and metallic, while the outer planets are largely composed of hydrogen, helium and other gases. b) Describe how the Nebular Theory of the origin of the solar system explains the difference in density between the inner and outer planets. Only high temperature materials (rock and metal) could condense near the sun and low temperature materials (hydrogen, helium, etc.) would condense in cooler regions away from the sun. Gravity pulls dense material to centre. Solar winds stripping lighter volatile gases from inner planets. 36. Many scientists suggest that a large meteorite impact contributed to a mass extinction of plant and animal life on Earth 65 million years ago. Since that time, the earth’s geological processes would have hidden most of the traces of such an impact, making it extremely difficult to find. Apart from the actual crater, describe two clues that might be found that would provide evidence of a large meteorite impact. Clue 1: Impact cracks. Clue 2: Ejecta patterns. Clue 3: Increased level of iridium. Clue 4: Distortion in surrounding area. Clue 5: Circular basins, raised perimeter. Clue 6: Compressed rock, shock-glass pellets (due to impact). Clue 7: Central raised peak, characteristic of meteorite impact. Clue 8: Fragments of meteor. - 14 - Answers to Unit 5 Workbook Metamorphic Rocks and Resources