Prepared by Pat Davis, Science Teacher, Durham Middle School, Lewisville ISD

1. SOLID EARTH Prepared by Pat Davis, Science Teacher, Durham Middle School, Lewisville ISD

2. The Science of Geology • Geology is the study of planet Earth, including Earth’s surface and interior. • Geologists study the physical and chemical characteristics of minerals and rocks, plus the processes that have shaped Earth. Geologists study physical conditions, such as temperatureandpressure, inside Earth. Geologists also study the forces inside Earth that affect the surface.

3. Inside Earth • Rock is the material that makes up Earth’s hard outer surface. • A layer of solid rock called the crust surrounds Earth’s surface like the tough shell of a walnut.

4. Rocks and the Rock Cycle • Rock forms Earth’s crust. • Rock is a solid material made up of one or more minerals or other substances, including the remains of once-living things. • Most of Earth’s rocks are made up of about 20 common minerals • Called rock-forming minerals.

5. Classifying Rocks • How they are formed: • Three ways: • Igneous • Sedimentary • Metamorphic

6. Igneous Rock • forms when magma or lava cools and hardens • Magma rises through cracks in rock deep beneath the surface. • Cools very slowly • Geologists classify igneous rocks according to whether the rocks formed above or beneath Earth’s surface • intrusive rock – formed beneath the surface • granite • extrusive rock – formed above the surface • basalt Basalt Granite Two common igneous rocks are basalt and granite. Basalt is a dark, extrusive rock that makes up much of the oceanic crust. Granite is a light-colored intrusive rock that is common in continental crust.

7. Igneous Rocks: Granite

8. Sedimentary Rock • forms when particles of rock and other materials are pressed and stuck together. • sediment --- particles of rock or material from living things. • sand and gravel on a beach and the mud on a riverbank are sediments. • All of these can make sedimentary rock. • erosion moves sediment from place to place • sediment is laid down in a process called deposition.

9. Horizontal Beds of Sedimentary Rock Source:William E. Ferguson

10. How Sedimentary Rock is Formed • Layers of sediment build up • Weight of the layers above presses down • Compaction, squeezes the layers • Cementation, glues the sediment together • Occurs when water dissolves some of the sediment • Compaction and cementation may continue for millions of years. • The sediment changes to sedimentary rock Sedimentary rocks form through the erosion, deposition, compaction, and cementation of sediments. (A) Water or wind deposits sediment. (B) The heavy sediments press down on the layers beneath. (C) Dissolved minerals flow between the particles and cement them together.

11. Metamorphic Rock • Created by heat and great pressuredeep beneath Earth’s surface. • Sometimes, heat from a volcano. • Any kind of rock can become a metamorphic rock Heat and pressure can change any rock into metamorphic rock. For example, granite becomes gneiss, and sandstone changes to quartzite.

12. Types of Rocks

13. The Rock Cycle • Forces inside Earth and at the surface produce a rock cycle that builds, destroys, and changes the rocks in the crust. • rock cycle is a series of processes on and beneath Earth’s surface that slowly change rocks from one kind to another.

14. The Rock Cycle Igneous, sedimentary, and metamorphic rocks change continuously through the rock cycle.

15. Key Ideas • Geologists study Earth and the processes that have shaped Earth over time. They study the minerals and rocks that make up Earth, physical conditions inside Earth, and the forces inside Earth that affect the surface.

16. Key Ideas • The three major groups of rocks are igneous, sedimentary, and metamorphic. • The series of processes on and beneath Earth’s surface that change rocks from one type to another is called the rock cycle. • Rocks can be formed when magma or lava hardens, when sediments are cemented and compacted together, or when heat and pressure change rock deep beneath Earth’s surface.