Sedimentary Rocks

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Sediments Noun

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[sed-uh-muhnts]

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Sediments

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Naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by various agents.

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Example: This image shows a conglomerate rock, which is formed when sediments like pebbles and sand are compacted and cemented together over a long period.

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Weathering Noun

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[weth-er-ing]

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Weathering

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The natural process that breaks down rocks, soils, and minerals through contact with the Earth's atmosphere and water.

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Example: A plant's roots grow into cracks in a rock, slowly forcing the cracks wider and breaking the rock apart in a process called biological weathering.

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Erosion Noun

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[ih-roh-zhuhn]

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Erosion

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The geological process in which earthen materials are worn away and transported by natural forces such as wind or water.

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Example: This diagram shows how faster-moving water on the outside of a river bend causes erosion, wearing away the bank and creating sediment.

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Deposition Noun

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[dep-uh-zish-uhn]

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Deposition

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The geological process in which sediments, soil, and rocks are added to a landform or land mass after being transported.

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Example: This diagram shows that deposition is the process where eroded materials, like sand and soil, are dropped and build up in a new location.

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Lithification Noun

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[lith-uh-fi-kay-shuhn]

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Lithification

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The complex process through which loose sediments are compacted under pressure and cemented to form solid sedimentary rock.

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Example: This diagram shows how loose sediments are first squeezed together (compaction) and then glued by minerals (cementation) to form solid sedimentary rock.

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Compaction Noun

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[kuhm-pak-shuhn]

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Compaction

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The process by which the porosity of a given form of sediment is decreased by the squeezing of its mineral grains.

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Example: Pressure from a load squeezes particles (like soil or sediment) closer together, reducing the space between them and decreasing the total volume.

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Cementation Noun

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[see-men-tay-shuhn]

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Cementation

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The hardening and welding of clastic sediments by the precipitation of mineral matter in the pore spaces between particles.

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Example: This diagram shows how natural minerals, called cement, fill the spaces between sediment grains, gluing them together to form a solid rock.

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Precipitation Noun

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[pri-sip-i-tey-shuhn]

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Precipitation

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The process where dissolved mineral constituents in a solution separate and crystallize to form a solid mineral deposit.

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Example: In geology, precipitation is when dissolved minerals come out of water to form a solid, like these cave formations, which are a type of sedimentary rock.

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Clastic Sedimentary Rock Noun

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[klas-tik sed-uh-men-tuh-ree rok]

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Clastic Sedimentary Rock

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A type of rock formed from the compaction and cementation of pre-existing rock fragments, which are known as clasts.

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Example: This image shows a clastic sedimentary rock, which is formed from broken pieces (clasts) of other rocks that have been cemented together.

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Conglomerate Noun

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[kuhn-glom-er-it]

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Conglomerate

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A coarse-grained clastic sedimentary rock composed of a substantial fraction of rounded to subangular gravel-sized clasts.

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Example: This image shows a conglomerate, a sedimentary rock made of large, rounded pebbles and stones (clasts) that have been cemented together by finer sediment.