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Geology. Rocks, Rocks & More Rocks! Chapter 3. Shows the interrelationships among the three rock types (igneous, sedimentary, and metamorphic) Magma is molten material that forms deep beneath the Earth’s surface. Lava is magma that reaches the surface.
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Geology Rocks, Rocks & More Rocks! Chapter 3
Shows the interrelationships among the three rock types(igneous, sedimentary, and metamorphic) Magmais molten material that forms deep beneath the Earth’s surface. Lavais magma that reaches the surface. Weatheringis a process in which rocks are broken down by water, air, and living things. Sedimentis weathered pieces of Earth elements. The Rock Cycle!
The Rock Cycle! It goes on and on and on…
Processes driven by heat from the Earth’s interior are responsible for forming both igneous rock and metamorphic rock. Weathering and the movement of weathered materials are external processes powered by energy from the sun. External processes produce sedimentary rocks. The Energy that Drives the Rock Cycle
ROCKS • Naturally occurring solid material made of one or more minerals • Grouped into 3 main types, based on the way it was formed (igneous, sedimentary and metamorphic)
IGNEOUS ROCKS #1
Igneous Rocks • Formed from magma that cools and hardens • “Fire Formed”
Intrusive rocks: formed deep within Earth Cools slowly, large crystals Coarse grained Extrusive rocks: formed from lava at Earth’s surface Cools quickly, small crystals fine grained IGNEOUS ROCKS: 2 types
IGNEOUS ROCKS: texture • Size of crystal grains and chemical composition are used to classify igneous rocks • Texture depends on time it takes a rock to harden (cooling rate)
IGNEOUS ROCKS: porphyry(POR-fuh-ree) • Igneous rock with a mixture of large and small crystals
Felsic: Light-colored Thick and slow flowing Rich in silica Mafic: Dark-colored Very fluid Rich in iron Two types of magma
Basalt Rhyolite
Scoria Gabbro
SEDIMENTARY ROCKS #2
Sedimentary Rocks • 75% of Earth’s surface is sedimentary rock!
How Sedimentary Rocks are made: • Mud, sand, gravel and shells are sediments that make up rocks • Sediments are moved by wind and water • Compaction: Pressure placed in sediment layers cause them to change to rocks • Cementation: sediments are joined together (cemented) by minerals dissolved in water • This process results in the formation of layers called strata.
The major characteristics of all sedimentary rocks is that they form layers!
"For your information, there's a lot more to ogres than people think... Ogres are like sedimentary rocks! …Sedimentary rocks have layers... Ogres have layers! ...We both have layers."
Sedimentary rocks usually form in water • Ripple marks and mud cracks
Sedimentary Rocks: Classified by • Composition • Texture • Grain size
Types: • Clastic • Organic • Chemical
1. Clastic Rocks • Formed by broken pieces or fragments of rock • Classified according to size and shape of fragments
Clastic Rocks Conglomerates: • Made of rounded pebbles and other rocks of different sizes and cemented together by clay, mud ,or sand • Formed when rivers deposit large pieces of rock • Pieces of rock rounded by water before deposited
Clastic Rocks Breccia: • Similar to conglomerates, but fragments are sharp and angular • Not carried far enough by water to round the edges
Clastic Rocks Sandstone: • Made of small, sand-sized grains • Very common • Resistant to wear and decay • Used to make buildings
Clastic Rocks Mudrock: • Formed from small particles of clay • Example: shale
2. Organic Rock • Formed directly or indirectly from material that used to be living
Organic Rock Fossilized Limestone: • Shells from dead animals (containing calcium carbonate) that sink to bottom of ocean floor
Organic Rock Chalk: Composed of animals and calcium carbonate that have been pressed together
Organic Rock Coal: • Rock formed from plants that lived millions of years ago
3. Chemical Rock • Formed by chemical means that do not involve any living organisms • Can occur through evaporation or chemical action
Chemical Rock Limestone: • Formed directly from ocean water instead of organisms