Chapter 4: Rocks. What is a rock? A ROCK is a mixture of minerals, mineraloids, glass, or organic...
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Transcript of Chapter 4: Rocks. What is a rock? A ROCK is a mixture of minerals, mineraloids, glass, or organic...
Chapter 4: Rocks
What is a rock?
• A ROCK is a mixture of minerals, mineraloids, glass, or organic matter.
3 Main Categories of Rocks
1.Igneous Rocks
2.Metamorphic Rocks
3.Sedimentary Rocks
Rock Cycle
• The process by which, over many years,
Earth materials form and change back and
forth among igneous rocks, sedimentary
rocks, and metamorphic rocks.
* The rock cycle can start with any rock – it is
a cycle
Processes of the Rock Cycle
Weathering-breaking of rocks into smaller pieces, either mechanically or chemically
Erosion-the process that wears away surface materials and moves them from one location to another, usually by gravity, glaciers, wind, or water.
Compaction-pressing sediments of rock together
Cementation-sediments naturally being glued together
Sediments-made from loose rock fragments
Igneous Rock Vocabulary
• Igneous Rock-most abundant rock on Earth because its inside and outside the earth, formed from magma and lava
• Intrusive-forms inside the earth from magma
• Extrusive-forms outside the earth from lava
• Granitic-magma is light colored, light weight, low density rocks like Pumice and Granite (Silicon,Oxygen)
• Andesitic-magma is of medium color and density, characteristics of both Basaltic and Granitic
• Basaltic-magma is dark colored, heavy rich in Iron and Magnesium, higher density.
*Density is how highly packed a substance’s molecules are. Mass/Volume.
Igneous Rock Examples
GranitePumice
Obsidian
Scoria
Facts about some Igneous Rocks
• Basalt – has iron in it and contains some air pockets.
• Pumice – is porous, and less dense than water so it will float.
• Obsidian – is glass like.
Minerals that make up Granite…
• Feldspar
• Quartz
• Mica
• Hornblend
• and others.
Metamorphic Rocks• Metamorphic-rocks that have changed due to
heat and pressure
• Foliated- type of metamorphic rock created when mineral grains flatten and line up in parallel bands
• Nonfoliated-type of metamorphic rock created when mineral grains change, grow, and rearrange – but do not form bands.
Metamorphic Rock Examples
Slate - foliated Marble – nonfoliated
Gneiss - foliated Quartzite – nonfoliated
Sedimentary Rocks
• Sedimentary Rocks-form when sediments get pressed or cemented together (Cementation and Compaction)
• Organic-made from the remains of once living things.
• Detrital/Clastic-made from broken rock fragments. They have texture.
• Chemical-when minerals precipitate out of a solution or left behind when a solution evaporates.
What is a Conglomerate?
• Conglomerate – sedimentary rock made of large well-rounded stones that have been cemented together.
Sedimentary Rock Examples
Shale - detrital Limestone - chemical
Coquina - organic Sandstone - detrital
Coal - organic
Conglomerate - detrital