The Rock Cycle Chapter 2 Section 1 p. 28 - 34 Vocabulary: 3. erosion 4. deposition 5. composition 6. texture

The Rock Cycle p. 28 Scientists define rock as a naturally occurring solid mixture of one or more minerals and organic matter. It may be hard to believe, but rocks are always changing. The continual process by which new rock forms from old rock is called the rock cycle. Rock has been an important natural resource as long as humans have existed. Early humans used rocks as hammers to make other tools. Rock has been used for centuries to make building monuments and roads. Buildings have been made out of granite, limestone, marble, sandstone, slate and other rocks.

Weathering, Erosion, and Deposition p. 29 The process in which water, wind, ice and heat break down rock is called weathering. Weathering is important because it breaks down rock into fragments. These rock and mineral fragments eventually make up sedimentary rock. The process by which sediment is removed from its source is called erosion. Water, wind, ice, and gravity can erode and move sediments and cause them to collect. The process in which sediment moved by erosion is dropped and comes to rest is called deposition. Sediment is deposited in bodies of water and other low-lying areas where it is pressed or cemented together forming sedimentary rock.

Heat and Pressure p. 29 If the temperature and pressure are high enough at the bottom of the sediment, the rock can change into metamorphic rock. In some cases, the rock gets hot enough to melt. This melting creates the magma the eventually cools to form igneous rock. How the Cycle Continues p. 29 Buried rock is exposed at the Earth’s surface by a combination or uplift and erosion. Uplift is movement within the Earth that causes rocks inside the Earth to be moved to the Earth’s surface. When uplifted rock reaches the surface, weathering, erosion, and deposition begin.

The Rock Cycle

Round and Round It Goes p. 32 Rocks may follow various pathways in the rock cycle. As one rock type is changed into another type, several variables, including time, heat, pressure, weathering, and erosion may alter a rock’s identity. The location of a rock determines which natural forces will have the biggest impact on the process of change. A rock at the surface will be primarily affected by forces of weathering and erosion. Deep within the Earth, rocks change because of extreme heat and pressure.

Composition Texture Rock Classification p. 33 Scientists classify rocks into three main categories, igneous, sedimentary, and metamorphic. Rocks can be ever further divided based on differences in the way the rocks form. All igneous rock forms when magma cools and solidifies. Some igneous rocks form when magma cools on the Earth’s surface, and others form when magma cools deep beneath the surface. Sedimentary and metamorphic rocks are also divided into groups. How do scientists know how to classify rocks? They study rocks in detail using two important criteria: Composition and Texture

Composition p. 33 The minerals a rock contains determine the composition of that rock. For example, a rock made mostly of the mineral quartz will have a composition very similar to that of quartz. Sedimentary rock Igneous rock

Texture p. 34 The size, shape, and positions of the grains that make up a rock determine a rock’s texture. Examples of grain size in sedimentary rock Sedimentary rock can have a fine grained, medium grained, or coarse grained texture. The texture of igneous rock can be fine grained or coarse grained, depending on how much time the magma has had to cool. Based on the degree of temperature and pressure a rock is exposed to, metamorphic rock can also have a fine grained or coarse grained texture.

Da Rock Cycle

Quiz Time! 1. Name some types of rock that have been used to construct buildings. granite, limestone, marble, sandstone, and slate 2. What processes change rock deep within the Earth? temperature and pressure 3. What determines a rock’s composition? The minerals that the rock contains determines its composition. 4. List the four processes that change rock from one type to another. weathering, change in pressure, melting, and cooling

5. What are the three main classes of rock? igneous, sedimentary and metamorphic 6. The minerals that a rock is made of determine the ________ of that rock. composition 7. ________ is a naturally occurring, solid mixture of crystals of one or more minerals. Rock 8. Sediments are transported or moved from their original source by a process called A. deposition B. erosion C. uplift D. weathering B