Sedimentary Rocks

It's hard to believe, but sedimentary rocks like this sandstone formation in Glen Canyon, Utah, are made from tiny bits of sediment. Pieces of rock, sand, and dirt are all sediment. Sediment is created through weathering and erosion. Wind, water, and ice all weather rocks. As the rocks weather, pieces of sediment are created. The sediment settles, or deposits, in one place and piles up. Just like the these cliffs that run along the Delaware River in Pennsylvania. Layer upon layer of sediment settle until the weight of the sediment squeezes the sediment together. Minerals that get mixed into the sediment help cement the sediment together (cementation). A good example of this is in this close-up photo of the Bright Angel Shale Formation. When shells and other matter fall between the layers of sediment, they become part of the rock. Sedimentary rock that is made up mostly of shell fragments is called coquina. The Watchtowers of Castillo de San Marcos is made of coquina. Several types of sedimentary rocks are used for building. Limestone and sandstone are examples. This limestone fossil reef, called Guadalupe Peak, formed over 200 million years ago in present-day Texas. Because sedimentary rocks often contain fossils, they help us learn about Earth's past. Here you can see the shale fossil of an Ichthyosaurus and 5 unborn babies. The Ichthyosaurus perished 66 million years ago--before the dinosaurs! 1. What characteristic do sedimentary rocks often have? glassy surfaces tiny crystals weather patterns striped layers 2. What is sediment? weather that occurs around fossils a kind of tall, jagged cliff rock that includes shells and ice pieces of rock, sand, and dirt 3. How does sediment become sedimentary rock? Sediment deposits in one place and settles in layers. The weight of the sediment squeezes the layers together into rock. Sediment deposits in one place and mixes together. Then wind, weather, and ice freeze the mixture into rock Sediment settles on limestone cliffs and inside caves. There, it forms minerals and turns into rock. Sediment mixes with seashells and fossils. Then wind, weather, and ice erode the mixture into sedimentary rock. 4. What keeps sedimentary rock stuck together? fossils coquina minerals seashells 5. What makes coquina unique? It has shells in its sediment. It can be used to build with. It only exists in the desert. It formed the Nockamixon Cliffs. 6. Which kind of sedimentary rock is used for building? pyroxene sandstone depository all of the above 7. How does sedimentary rock help scientists learn about the Earth’s past? It contains fossils. It is in Texas. It is used in buildings. It contains minerals. 8. When a fossil is found it tells us about the earth's environment that happened a long time ago. True False 9. The rock layer that is on the top is the - youngest Middle aged Oldest 10. To make a sedimentary rock it usually takes - 100 years thousands of years 500 years millions of years Sedimentary Rocks: StudyJams! Science Credits