Chapter 2 Rocks: Mineral Mixtures

1. Chapter 2Rocks: Mineral Mixtures

2. Section 1The Rock Cycle

3. rock • always changing • a naturally occurring solid mixture of one or more minerals and/or organic matter

4. rock cycle • the series of processes in which a rock forms, changes from one type to another, is destroyed and forms again by geological processes

5. weathering • the process in which water, wind, ice and heat break down rock • breaks rock down into fragments (which sedimentary rock is made)

6. erosion • the process by which wind, water, ice or gravity transports soil and sediment from one location to another

7. deposition • the process in which sediment is moved by erosion and comes to rest in a new location • sediment is deposited in bodies of water and other low-lying areas • sediment may be pressed and cemented together by minerals dissolved in water to form sedimentary rock

9. uplift • movement within the Earth that causes rocks inside the Earth to be moved to the Earth’s surface • when rock is uplifted to surface weathering, erosion and deposition begin

10. magma • the hot liquid that forms when rock partially or completely melts • 3 ways magma can form: 1) when rock is heated 2) pressure is released 3) when rock changes composition • freezes between 700º and 1250º C

11. composition • the chemical makeup of a rock • describes either the minerals or other materials in the rock • limestone = 95% calcite and 5% aragonite • granite = 55% feldspar, 35% quartz and 10% biotite mica

12. texture • the quality of a rock that is based on the sizes, shapes and positions of the rock’s grains • examples = fine grained, medium grained or coarse grained texture • can provide clues as to how and where the rock formed

13. SECTION 2IGNEOUS ROCKS

15. igneous rock • forms when hot, liquid rock (magma) cools and solidifies • are located above and below the surface

16. felsic rocks • igneous rocks that are light in color and rich in elements such as aluminum, potassium, silicon and sodium • examples = granite and rhyolite

17. mafic rocks • igneous rocks that are dark in color and rich in calcium, iron and magnesium (poor in silicon) • examples = gabbro and basalt

19. intrusive igneous rock • rock formed from the cooling and solidification of magma beneath the Earth’s surface • usually have a coarse grained texture • cools very slowly and forms minerals that are large, visible crystals • common intrusive shapes = plutons, batholiths, stocks, dikes and sills

20. intrusive igneous rock

21. extrusive igneous rock • rock that forms as a result of volcanic activity at or near the Earth’s surface • also called lava rocks • common around volcanoes • cools quickly and contain very small or no crystals

22. extrusive igneous rock

24. lava plateau • when a large amount of lava flows out of fissures onto land and covers a large area • pre-existing landforms are often buried by these lava flows

26. Section 3SEDIMENTARY ROCK

28. sandstone • when sand grains are compacted or compressed and then cemented together • one of the many types of sedimentary rock

29. sedimentary rock • through erosion rock and mineral fragments are moved from one place to another and eventually deposit in layers. As new layers arrive, old layers are compacted & cemented together binding minerals and rock together • form at or near the Earth’s surface • forms without heat and pressure • most noticeable feature is the layers/strata • fossils can only be found in sedimentary rock

31. strata • horizontal layers of rock

32. clastic sedimentary rock • forms when rock or mineral fragments (called clasts) are cemented together by minerals such as calcite or quartz • classified according to the size of fragments: fine, medium and coarse grained

34. chemical sedimentary rock • forms from solutions of dissolved minerals and water • when minerals crystallize out of a solution, such as sea water to become rock • example = halite

35. organic sedimentary rock • forms from the remains or fossils of once living plants and animals • example = many limestone made of skeletons of tiny organisms (coral) • example = coal

36. stratification • the process in which sedimentary rocks are arranged in layers • differ from one another depending on the kind, size and color of their sediment

39. Section 4Metamorphic Rock

41. metamorphic rock • rocks in which the structure, texture or composition of the rock have changed • all metamorphic rock has 1 of 2 textures: foliated or nonfoliated

42. metamorphism • when rocks change shape • all three types of rock can be changed by heat, pressure or a combination of both

43. contact metamorphism • when rock is heated by nearby magma • occurs near igneous intrusions

44. regional metamorphism • when pressure builds up in rock that is buried deep below other rock formations or when large pieces of the Earth’s crust collide with each other • causes rock to become deformed and chemically change • occurs over thousands of cubic kilometers deep within Earth’s crust

45. regional metamorphism

47. foliated • the texture of metamorphic rock in which the mineral grains are arranged in planes or bands • usually contain aligned grains or flat minerals such as mica or chlorite • example= shale slate phyllite schist gneiss

48. foliated

49. nonfoliated • the texture of metamorphic rock in which the minerals are not arranged in planes or bands • commonly made of one or only a few minerals • Example= quartz sandstone quartzite orlimestone marble