University:
Bradley University
Course:
GES 101 | Principles of Earth Science
Academic year:

2021
Views:

294

Pages:

61
Author:

Gudrunecg9m

• When studying rocks, geologists observe the rock’s composition, color, & texture. • Shape & color identify the minerals in a rock. • Rocks are made of mixtures of minerals. • Some made of one mineral & some are made of many. • Granite-made of quartz, feldspar, & mica. • 20 minerals that make up most of the earth’s crust. • Provides clues to the rock’s mineral composition. • Granite- light colored with high silica content. • Basalt- dark, & low in silica. • The look & feel of the surface. • Most rocks are made up of minerals called Grains. • Grains give the texture. •To describe a rock’s texture, geologists use size, shape, & pattern of grains. •Coarse-Grained- grains in rock are large & easy to see. •Fine-Grained- grains that are very small (microscope). Grain shape results from shapes of crystals that form the rock. • Can be rounded, smooth, or jagged. 1. Nonbanded- swirling pattern, Quartz 2. Banded- flat layers that look like pancakes, Gneiss. Geologists classify rocks into 3 groups: 1. Igneous rock 2. Sedimentary rock 3. Metamorphic rock • FORMS FROM THE COOLING OF MAGMA OR LAVA ON OR BENEATH THE EARTH’S SURFACE. • Igneous = fire • Classified according to origin, texture, & mineral composition. • Forms on or beneath earth’s surface. 1. Extrusive rock- formed from lava that erupted onto earth’s surface. Basalt- found on ocean floor. Basaltfine grained, glassy • texture. 2. Intrusive rock- rock formed when magma hardened beneath earth’s surface. Granite (coarse grained texture) • Depends on size & shape of its mineral crystals. • Rapidly cooling lava forms fine-grained rocks with small crystals. Slow cooling magma forms coarse-grained rocks with large crystals. • Silica- a material formed from oxygen & silicon. • Silica content affects the types of rocks they form. • Lava that is low in silica usually forms dark-colored rocks. Basalt • Magma that is high in silica usually forms light-colored rocks. Granite • Igneous rocks are hard, dense, & durable. • Used for tools & building materials. • Granite- building bridges, statues, floors, & kitchens. • Pumice- rough surface makes a good abrasive for cleaning. • Basalt- road construction • Sediment- small, solid particles that come from rocks or living things. • Form when sediment is deposited by water & wind. • Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, & cementation. • Running water, wind, or ice loosen & carry away rock fragments. • Break down or wear away rock. • Process by which sediment settles in clumps in layers & sinks to bottom of a lake or ocean. • Process that presses sediment together. • Layers build up over millions of years. • layers above & below push together. • Process in which dissolved minerals crystallize & glue particles of sediment together. •CLASSIFIED BY THE TYPES OF SEDIMENTS THAT MAKE UP THE ROCK. • Clastic • Organic • Chemical • A rock that forms when rock fragments are squeezed together. • Shale, sandstone, breccia • Shale- forms from clay • Sandstone- sand from beaches • Conglomerate- rounded edges • Brecci- large fragments with sharp edges. • Forms when the remains of dead plants & animals mix into the ground. • Organic- living • Coal, limestone • Formed when minerals dissolve in a solution & crystallize. • Limestone- calcite dissolves in seas to form crystals. • Building materials, tools • Flint-arrow heads, • Sandstone- cut into slabs, White House • Coral animals live together in vast numbers & produce skeletons that grow together to form a coral reef. • Small animals with tentacles, algae grow within their bodies. • Algae provides substances for the animal to grow & live. • The animal provides a framework for the algae to grow on. • Coral animals absorb calcium from the water to make their skeletons. • Ca + O + C= Calcite • When it dies, the skeleton remains. More corals build on top of them forming a c. reef. • Need warm, shallow water & sunlight. • Most abundant around islands of tropical oceans. • In US, S. Florida, & Hawaii • Limestone deposits from coral reefs formed millions of years ago. • Deposits help geologists understand past environments. • As water retreated, limestone was exposed. • “Meta”- change •Heat & Pressure deep below earth’s surface can change a rock into a metamorphic rock. • Classified according to the arrangement of the grains that make up the rocks. • Heat changes size & shape • Pressure causes grains to line up in flat layers. • Metamorphic rocks that have their grains arranged in parallel layers or bands. • Slate, Schist • Minerals are arranged randomly in these rocks. • Do not split into layers. • Marble, Quartzite • Building & sculpture • Marble- Lincoln Memorial • Slate- flooring, walkways, trim for stone buildings. • A series of processes on earth’s surface, crust, & mantle that slowly change rocks from one kind & another. • Forces build, destroy, & change rocks Cycle’s Many Pathways • Igneous rocks- volcanic activity magma/lava melts & then cools. • Sedimentary-rocks erode, mix in with ground • Metamorphic- igneous rock is buried, exposed to heat & pressure, & changed. Products of Rock Cycle •Magma, igneous rock, sediment, sedimentary rock, metamorphic rock. Processes that occur • Melting, cooling, erosion, deposition, compaction, & cementation.

Geologists Classify Metamorphic Rocks According to

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