Earth’s Surface Chapter 4 A Trip Through Geologic Time Review and Reinforce Lesson Quiz Answer Keys

Lesson 1 Fossils Review and Reinforce Worksheet 1. minerals 2. Mold 3. Cast 4. carbon 5. activities 6. Preserved remains 7. A mold is an empty space in rock in the shape of an organism or part of an organism. If water carrying dissolved minerals and sediment seeps and deposits those minerals and sediments into the mold, the result is a cast in the shape of the organism. 8. Fossil footprints can provide clues about the dinosaur’s size and behavior. 9. The fossil record provides evidence that many different organisms have existed at different times. The fossil record also shows that groups of organisms have changed over time. 10. C 11. E 12. A 13. B 14. F 15. D

Lesson 1 Fossils Quiz 1. B 3. C 5. sediment 7. paleontologist 9. Evolution 2. C 4. B 6. carbon film 8. fossil record 10. extinct

Lesson 2 The Relative Age of Rocks Review and Reinforce Worksheet 1. Layer C is the youngest because the law of superposition says that a layer is younger than the layers below it. 2. The extrusion is younger because extrusions are always younger than the rock layers below them. 3. The fault is younger than layer A because rock layers are always older than the faults they contain. 4. The fossil might be an index fossil. Geologists can use index fossils to match rock layers at locations that are far apart.

Lesson 2 The Relative Age of Rocks Quiz 3. D 5. superposition 7. erosion 9. folding 2. D 4. B 6. intrusion 8. unconformity 10. superposition

Lesson 3 Radioactive Dating Reinforce Worksheet 1. Since radioactive dating is used only on igneous rock, this process would not work on sedimentary layers A, B, C, D, and E. Sedimentary rock layers are made of particles from other rocks. Dating would provide the ages of those particles, not of the rock itself. 2. They can use radioactive dating because extrusions and intrusions are made of igneous rock. 3. Rock layer C is at least 80 million years old. It is possible to identify its relative age because we know the age of the intrusion that cuts partway across it. An intrusion is always younger than the rock it cuts through. 4. Radioactive dating is based on the concept of radioactive decay. During radioactive decay, the atoms of one element break down to form the elements of another element. 5. radioactive decay 6. radioactive 7. half-life

Lesson 3 Radioactive Dating 1. true 3. never changes 5. true 7. radioactive 9. Half-life 2. true 4. igneous 6. true 8. Radioactive dating 10. radioactive decay

Lesson 4 The Geologic Time Scale Review and Reinforce Worksheet 4. B 5. Geologists use the geologic time scale to show Earth’s history because the time span of Earth’s past is so great. 6. Geologists subdivide eras into periods. 7. They studied rock layers and index fossils worldwide. With that information, they placed Earth’s rock layers in order by relative age. 8. The divisions of the geologic time scale depend on events in the history of life on Earth. 9. A 10. C 11. B

Lesson 4 The Geologic Time Scale Quiz 1. true 3. false; three 5. geologic 7. Precambrian Time 9. Mesozoic 2. true 4. false; Eras, periods 6. life forms 8. eras 10. Names

Lesson 5 Early Earth Review and Reinforce Worksheet 6. B 7. They were single-celled organisms that were probably similar to present-day bacteria. 8. When Earth was very young, it collided with a large object. The collision threw a large amount of material from both bodies into orbit around Earth. This material combined to form the moon. 9. In photosynthesis, oxygen is released as a waste product. Oxygen released into the air was changed into ozone, which blocks out ultraviolet rays of the sun. 10. Scientists used radioactive dating to show that the oldest moon rocks are about 4.6 billion years old. Because Earth is slightly older than the moon, Earth must be roughly 4.6 billion years old. 11. comet 12. photosynthesis

Lesson 5 Early Earth Quiz 1. B 3. A 5. Earth 7. Gravity 9. landmasses 2. C 4. D 6. ice 8. comet 10. melted

Lesson 6 Eras of Earth’s History Review and Reinforce Worksheet 1. Silurian Period 2. Paleozoic Era 3. Devonian Period 4. Permian Period 5. Mesozoic Era 6. Cretaceous Period 7. Triassic Period 8. Cenozoic Era 9. Quaternary Period 10. f 12. e 14. d 11. c 13. a 15. b

Lesson 6 Eras of Earth’s History Quiz 1. true 3. true 5. vertebrates 7. mass extinction 9. mammals 2. invertebrate 4. true 6. true 8. Reptiles 10. Quaternary Period