Introduction

Sedimentary rocks are like pages in which Earth’s history is written, because they contain powerful environmental indicators, traces of life, and chemical signatures that can tell us about many events, from the occurrence of ancient catastrophes to the evolution of life.

Identifying sedimentary rocks is more than just applying names, because each name implies something about the history of a rock, whether that be where the rock was formed, when it was formed, or what processes led to its formation.

Sedimentary rocks are puzzles, and by identifying a set of rocks, how they are layered, the fossils within, and patterns in the rocks, a geologist can reconstruct an entire environment and ecosystem. Solving these puzzles is both an academic exercise to better understand the world around us, and a tool for finding the resources that are important to our lives. In particular, sedimentary rocks provide or contain resources such as coal, natural gas, petroleum, salt, and even the materials that go into wallboard or into the making of cement. Therefore, having a better understanding of sedimentary rocks and how and where they are formed means knowing more about the materials that directly influence your everyday life.

Learning Outcomes

After completing this chapter, you should be able to:

• Describe how erosion and weathering relate to the formation of sedimentary rocks.
• Identify sedimentary rocks and their features.
• Describe the formation and history of different types of sedimentary rocks.

Key Terms

• Biochemical sedimentary rocks (fossiliferous limestone)
• Bituminous coal
• Chemical sedimentary rocks (oolitic limestone)
• Chemical weathering
• Clast
• Clastic sedimentary rocks (conglomerate, breccia, arkose sandstone, quartz sandstone, siltstone, shale)
• Coquina
• Dissolution
• Erosion
• Hydrolysis
• Lignite
• Maturity
• Mechanical weathering
• Oxidation
• Sorting

Attributions

Adapted from:

McBeth, J., Panchuk, K., Prokopiuk, T., Hauber, L., & Lacey, S. (2020). Introductory Physical Geology Laboratory Manual, 1st Canadian Ed., Chapter 4. Sedimentary Rocks by L. Hauber & J. McBeth. CC BY-SA 4.0

Deline, B., Harris. R. & Tefend, K. (2015) Laboratory Manual for Introductory Geology, 1st Edition, Chapter 10. Sedimentary Rocks by B. Deline. CC BY-SA 4.0