9.1.1: Importance of Sediment

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Why Sedimentology Matters

Sediments and sedimentary rocks cover most of Earth, and weathering is occurring on the rest of it. The reshaping of the surface of the Earth has had a huge influence on the planet, affecting everything from the evolution of life to the tectonics of mountain ranges. Sediments and sedimentary rocks record the events and processes that shaped the surface of Earth – and other rocky planets. They provide the temporal framework that connects processes within the Earth to those at the surface. They are important for:

Earth history. Sedimentary rocks contain features that allow us to interpret ancient depositional environments, including the evolution of organisms and the environments they lived in, how climate has changed throughout Earth history, where and when faults were active, etc.
Economic resources. Petroleum reservoirs have organic-rich, sedimentary source rocks that produced the petroleum when heated, most oil and gas migrates through sedimentary rocks, and most of the reservoirs are hosted in sedimentary rocks. Water aquifers are dominantly found in sedimentary rocks (although some are in fractured metamorphic and igneous rocks). The composition of the rocks strongly influences water quality due to water-rock interactions. (Why does Davis water taste bad?) Sedimentary rocks also host economic minerals such as gold and diamonds, which are eroded from other rocks and concentrated to specific areas during sediment transport.
Environmental geology. Sediments cover 2/3 of the continents and essentially all of the ocean floor, which totals 89% of the surface of Earth. They host the biosphere, and they are most of the rocks we interact with directly and indirectly. Our actions as humans have an extremely strong effect on sedimentation and erosion. Understanding our impact on the environment - and the environment’s impact on us - must include deep appreciation for sediments and sediment transport.

Case Study: Oroville Dam and Sediment Transport