Sedimentary Rock c. Classify rocks by their process of formation. d. Describe processes that change rocks and the surface of the earth.

Sedimentary Rock Formed from particles of sediment deposited by wind and water. Sediment is small pieces of solid materials that come from rocks or living things.

Stratification Yes, all these rocks are layered or “stratified.”

Weathering The process by which exposed rock is broken down into small pieces by the elements of nature (wind, rain, ice, chemical actions, plants, etc.)

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.

Erosion Occurs when water or wind loosens rock and soil and carries it away.

Deposition The process by which the sediment settles out of the water or air carrying it. Sediment is deposited when the wind or water slows down.

Compaction As the sediments settle they will loosely fit on top of each other. As the years go by, more and more sediment is added. The bottom layers get compacted by the weight of the layers above them.

Cementation While compaction is going on, minerals in the rock slowly dissolve. The dissolved minerals seep into the spaces between the compacted sediment. They crystallize and glue the sediments together.

Lithification The process by which sediment becomes sedimentary rock. From Greek word “lithos,” which means rock. Erosion Deposition Compaction

Types of Sedimentary Rock Clastic: formed when rock fragments are squeezed together. Organic: (biological) formed from the remains of living things. Chemical: formed when dissolved minerals crystallize.

Conglomerate and Breccia Formed from a mixture of rock fragments of different sizes. Conglomerate has rounded edges. Breccia has larger fragments with sharp edges

Sandstone Formed from sand on beaches, ocean floors, river beds, and deserts. Mainly quartz.

Shale Clastic rock formed from tiny particles of clay. Water deposits tiny clay particles in thin layers. Feels smooth and splits easily into flat sheets.

Organic Sedimentary Rock Formed from the remains of plants and animals that were deposited in thick layers. Also called biological rock.

Coal Formed from the remains of ancient swamps. As layer upon layer of dead plants built up, the bottom layers were compacted into coal. Stored chemical energy

Limestone Formed from the shells of ancient sea animals and plants. Shells fall to the bottom of the ocean in layers, some 100’s of meters thick. Compaction creates limestone.

Chalk Formed from the shells of ancient sea life. Creates layers 100’s of feet thick. White Cliffs of Dover

Chemical Sedimentary Rock Formed when water with dissolved minerals evaporates. The left behind minerals will crystallize.

Halite Rock Salt Formed from seas and oceans that dried up. The salt forms large crystals.

Gypsum Made from calcium deposits. Used to make sheet rock for homes.