Presentation on theme: "Earth Science Rock & Minerals 4.3 – 4.4. What have we already learned about sediments/sedimentary rocks? Sediments may include: Fragments of other rocks."— Presentation transcript:
What have we already learned about sediments/sedimentary rocks? Sediments may include: Fragments of other rocks that have been worn down into small pieces Organic materials: the remains of once-living organisms Chemical precipitates: minerals that get left behind after the water evaporates form a solution Sedimentary rocks are part of the rock cycle! They are made from sediments. Sedimentary rocks are formed by the compaction of sediments.
How do we get sediments? Most sediments settle out of water Example: running waters in rivers One layer of sediment is deposited at a time. When sediments harden, the layers are preserved. In large outcrops of sediments, you can see the layers that make up sedimentary rocks.
Environments where sedimentary rocks form: There are MANY environments where sedimentary rocks can form. Mostly places that have water involved!!! Beach, oceans, lakes, ponds, rivers, marshes swamps Also find sedimentary rocks forming in deserts and mountains where avalanches have occurred.
How do sedimentary rocks form?? 1. Sediments accumulate 2. Lithification occurs
Lithification Lithification: the hardening of layers of loose sediment into rock Made up of 2 processes – 1. Cementation: occurs when substances crystallize or fill in the spaces between the loose particles of sediment 2. Compaction: when sediments are squeezed together by the weight of layers on top of them
Classification of Sedimentary Rocks Clastic Rocks: sedimentary rocks made of cemented, non- organic sediments Bioclastic Rocks: sedimentary rocks made of cemented organic sediments Chemical Sedimentary Rocks: sedimentary rocks made by the hardening of chemical precipitates
Summary Write a 3 sentence summary about sedimentary rocks!!
How do we get metamorphic rocks? Metamorphic rocks start off as igneous, sedimentary, or other metamorphic rocks. These rocks are changed when heat or pressure changes the rock’s physical/chemical make-up. Metamorphism DOES NOT completely melt the rock, it just heats it up and changes it!
Foliation Foliation: flat layers in rocks that form as the rocks are squeezed by pressure. Normally forms when pressure was exerted on a rock from one direction. If pressure is exerted from all directions, no foliation occurs.
Types of Metamorphism 1. Contact metamorphism: occurs when magma contacts a rock, changing it by extreme heat 2. Regional metamorphism: occurs when great masses of rocks change over a wide area due to pressure deep within the earth or through extreme pressure from rock layers on top of it.
Summary Write a 3 sentence summary about metamorphic rocks!!
Vocabulary for Ch. 4 1. Sediments 2. Solidify 3. Intrusive 4. Extrusive 5. Mafic 6. Felsic 7. Ultramafic 8. Compaction 9. Cementation 10. Clastic Rock 11. Bioclastic Rock 12. Chemical Sedimentary Rock 13. Contact metamorphism 14. Regional metamophism 15. Foliation