2. Objectives: Describe the origin of sedimentary rock. Describethe three main categories of sedimentary rock. Describe three types of sedimentary structure.
3. Origins of Sedimentary Rock Wind, water, ice, sunlight, and gravity all cause rock to physically weather into fragments Through erosion, these rock and mineral fragments, called sediment, are moved from one place to another. The sediment is deposited in layers, and eventually newer layers cover the older layers.
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5. The most noticeable feature of sedimentary rock is its layers, or strata. A single, horizontal layer of rock is sometimes visible for many miles.
6. Composition of Sedimentary rock Sedimentary rock is classified by the way it forms. Clastic sedimentary rock made of fragments of rocks cemented together by a mineral such as calcite or quartz. can have coarse-grained, medium-grained, or fine-grained textures. Sandstone Siltstone Conglomerate Shale Fine – grained Course – grained
7. Chemical sedimentary rockforms from solutions of dissolved mineral and water. As rainwater slowly makes its way to the ocean, it dissolves some of the rock material it passes through Some of this dissolved material eventually crystallized and forms the mineral that make up chemical sedimentary rock. Halite
8. Organic sedimentary rock made up of the skeletons and shells of sea animals These remains collect on the ocean floor and eventually become cemented together Coal is a type of organic sedimentary rock that is formed when decomposed plant material is buried beneath sediment and is changed by increasing heat and pressure. Chalk Coal
9. Sedimentary Rock Structures Many features indicate the way sedimentary rock is formed Most important feature is stratification the process in which sedimentary rocks are arranged in layers Strata differ from one another depending on Kind Size Color
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11. Ripple marks Features in which sedimentary rocks sometimes record the motion of wind and water waves on lakes, oceans, rivers, and sand dunes Mud cracks Structures that form when fine-grained sediments at the bottom of a shallow body of water are exposed to the air and dry out. Even raindrop impressions can be preserved in fine-grained sediments, as small pits with raised rims.
