UNIT SIX: Earth's Structure. Part 18 Earth's History and RocksChapter 19 Changing EarthChapter 20 Earthquakes and Volcanoes. Section Eighteen: Earth's History and Rocks. 18.1 Geologic Time18.2 Relative Dating18.3 The Rock Cycle. 18.1 Learning Goals. Talk about the occasions connected with times of Earth's history.Apply learning of isotopes to clarify how radiometric dating is utilized to fi