Sedimentary Rocks

most of the rocks found at Earth's surface are sedimentary rocks ous and metamorphic rocks usually form deep underground but sedimentary rocks form above ground this makes them easy to find and observe where do sedimentary rocks come from sedimentary rocks start out as other rocks and even shells over time little bits of rocks break off in process called weathering changes in temperature can cause weathering when water in the cracks of rocks freezes it expands and can break apart the rock animals break apart rocks when they dig to build nests and Burrows plant roots also break rocks as they grow moving water is another big cause of weathering Rivers streams and even raindrops dissolve tiny pieces of rock as they pass by the little pieces that break off of rocks are called sediment this is where the name sedimentary comes from sediment is eroded or Carried Away by wind water or gravity next it is deposited and collects somewhere after many years more and more layers of sediment build up in that place the weight of all those layers presses the tiny pieces of sediment together this is called compaction water fills the gaps between the small pieces of rock this water has dissolved minerals in it as the water evaporates the minerals are left behind they Harden into kind of cement sort of like glue which holds the sediment together together this is called cementation together compaction and cementation press and glue sediment together to form sedimentary rock there are different types of sedimentary rocks conglomerate has larger pieces of sediment like small rocks cemented together Sandstone is made of grains of sand pressed and cemented together the set that makes up mudstone and Shale is even smaller and finer than Sandstone Limestone forms from the shells of sea creatures instead of rock sediment sedimentary rocks often contain fossils because of the way they form the bodies of ancient organisms become buried with sediment as the sediment is compacted and cemented into rock an imprint of the organism is Left Behind studying sedimentary rocks and the fossils they hold can tell us lot about Earth we can learn about ancient plants and animals and how Earth has changed over time this video was created by La Fontaine of knowledge click the link in the description for lesson materials that go along with the video and subscribe to my channel for more videos like this