Rocks Charity I. Mulig
Definition Rocks are any solid mass of mineral or mineral-like matter occurring naturally as part of our planet. Rocks are often made of several different minerals.
The Value of Rocks Rock is an important natural resource. Used by early humans to make tools such as hammers, spears, knives, and scrapers. Used for centuries to make buildings, roads, and monuments. Certain types of rocks have helped build ancient and modern civilizations. Rock study has helped scientists to discover the history of life on Earth.
Types of Rocks Igneous rock is formed by the crystallization of molten magma. Sedimentary rock is formed from the weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented. Metamorphic rock is formed by the alteration of pre-existing rock deep within Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids.
The Rock Cycle
Igneous Rocks
Formation of Igneous Rocks Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface. Extrusive igneous rocks are formed when lava hardens.
Classification of Igneous Rocks
Fine-Grained Igneous Rock Coarse-Grained Igneous Rock Glassy- textured Obsidian Porphyritic Igneous Rock
Sedimentary Rocks
Formation of Sedimentary Rocks Process What happens? Weathering rocks are broken down by water, air, and living things. Erosion rocks are transported from one place to another Deposition rock fragments are dropped when agents of erosion losses energy Compaction rock fragments are squeezed together Cementation dissolved minerals are deposited in the tiny spaces among the sediments * Compaction and cementation are collectively called lithification.
Classification of Sedimentary Rocks
Examples Shale with Fossils Conglomerate
Metamorphic Rocks
Formation of Metamorphic Rock Metamorphism means “to change form.” occur at elevated temperatures and pressures Conditions for formation are found a few kilometers below the Earth’s surface and extend into the upper mantle.
Agents of Metamorphism Heat provides the energy needed to drive chemical reactions. Pressure produces more compact rocks with greater density. Hydrothermal Solutions are hot water-based solutions escaping from the mass of magma which promotes recrystallization by dissolving original minerals and then depositing new ones
Types of Metamorphism Contact Metamorphism Regional Metamorphism occurs when magma moves into rock. Occurs near a body of magma Changes are driven by a rise in temperature results in large-scale deformation and high-grade metamorphism. Directed pressures and high temperatures occur during mountain building. Produces the greatest volume of metamorphic rock
Classification of Metamorphic Rocks
Sources of Heat and Pressure
Examples Banded Gneiss Non-Foliated Marble
Pictures Igneous Rocks Sedimentary Rocks http://geology.com/rocks/igneous-rocks.shtml Sedimentary Rocks http://geology.com/rocks/sedimentary- rocks.shtml Metamorphic Rocks http://geology.com/rocks/metamorphic- rocks.shtml