Sedimentary Rocks and Earth’s Past — Formation, Types, and Interpreting Ancient Environments | Chapter 7 from Earth: Portrait of a Planet
Sedimentary Rocks and Earth’s Past — Formation, Types, and Interpreting Ancient Environments | Chapter 7 from Earth: Portrait of a Planet How do rivers, oceans, and deserts write the pages of Earth’s past? In Chapter 7 of Earth: Portrait of a Planet by Stephen Marshak, we unlock the secrets of sedimentary rocks—nature’s historical archives. For a full audio summary, watch the chapter video on YouTube , or continue reading for a comprehensive written guide. How Sedimentary Rocks Form Sedimentary rocks begin as loose fragments—sediments—created by the weathering and erosion of pre-existing rocks. These sediments are transported by water, wind, or ice, deposited in layers, and eventually lithified (turned to stone) by compaction and cementation. The process preserves vital clues about ancient landscapes, climates, and life. The Four Types of Sedimentary Rocks Clastic: Made from fragments (clasts) of other rocks—classified by grain size, sorting, and composition. Includ...