Chapter 2 Test Review Sheet “Rocks: Mineral Mixtures” 1. What are the three types of sedimentary rocks? Explain the differences between the three. Clastic – sedimentary rocks that are made when rock fragments are cemented together Chemical – sedimentary rocks that are formed when water evaporates leaving cemented sediment behind Organic – sedimentary rocks that form from the remains (or fossils) of living things. 2. What is the difference between intrusive and extrusive igneous rocks? Intrusive igneous rocks form when magma cools inside other rock under the Earth’s surface, while extrusive igneous rock forms when lava cools on the Earth’s surface. 3. What is the difference between foliated and nonfoliated metamorphic rocks? Foliated metamorphic rocks form with minerals in plains or bands; nonfoliated metamorphic rocks form without the plains or bands and usually have recrystallization 4. How is sediment formed? from the erosion and weathering of rocks 5. What causes a sedimentary rock to become a metamorphic rock? when sedimentary rock is exposed to heat and pressure it will become a metamorphic rock 6. What is formed when rocks melt? magma 7. What is deposition? The process in which sediment moved by erosion is dropped and comes to rest is called deposition 8. What causes coarse-grained and fine-grained igneous rocks? when igneous rocks cool quickly they become fine-grained. The slower they cool, the coarser they will become. 9. When metamorphism occurs, these two things must increase? heat and pressure 10. What did ancient humans use rocks for? tools 11. What is deformation? Deformation is a change in the shape of a rock caused by a force placed on it 12. What is stratification? the process in which sedimentary rocks are formed in layers 13. What is a fissure? large cracks in the earth’s surface from which lava occasionally flows 14. How are folds or bends formed in rocks? through the process of deformation 15. What process can change rocks on the Earth’s surface? erosion 16. What determines the composition of rock? the minerals it is made of 17. What are strata? layers of rock, usually in sedimentary rocks 18. How do scientists classify rocks? by composition and texture 19. What are mud-cracks and how do they form? sedimentary rocks that are created when fine-grained sediments are exposed to the air and dry out 20. How are igneous rocks formed? when magma cools 21. How are sedimentary rocks formed? when pieces of sediment are cemented together by available water 22. How are metamorphic rocks formed? when rocks are exposed to high heat and pressure that changes the mineral composition while still remaining a solid.