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Rocks/minerals. Learning Targets. I can classify jelly beans in preparation of classifying rocks and minerals. I can construct an explanation of how to classify rocks by their formation and how rocks change through geologic processes in the rock cycle. Types of rocks (Flocabulary).
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Learning Targets • I can classify jelly beans in preparation of classifying rocks and minerals. • I can construct an explanation of how to classify rocks by their formation and how rocks change through geologic processes in the rock cycle.
Types of rocks (Flocabulary) • Classify jelly beans
Think-pair-share • What do you think we will be doing the rest off this week? • How do the jelly beans relate to rocks?
Homework • At home, go outside and collect as many different rocks as possible. (large, small, pretty, unusual, rock with two or more colors). Place them in a Ziploc bag.
Learning Targets • I can construct an explanation of how to classify rocks by their formation and how rocks change through geologic processes in the rock cycle.
Rocks • Naturally formed, nonliving, firm and coherent mass of solid earth material. • Rocks are classified by their origin (how they formed)
Igneous rocks • Form from the crystallization of a molten mixture of minerals and dissolved gasses. • magma - molten rock underground • lava - molten rock at the surface
Igneous rocks • As the molten rock cools, the ions in the liquid slow down and join into molecules of minerals.
Intrusive • If cooling is slow as would happen inside the earth, large/coarse mineral grains will form
Extrusive • If cooling is quick as would happen at or near the surface, small/fine mineral grains will form
If cooling is too quick, minerals may not form. (amorphous/glassy texture)
In rare cases, magma begins to cool slowly at depth, then rises quickly and cools forming porphyry.
If gas bubbles are escaping from lava as it cools, a vesicular texture forms
Composition • The mineral composition of igneous rocks depends on the magma from which it solidifies.
Felsic Magma/Felsic Rocks • Light color • Low density • Usually form on continents. • Forms rocks that are pink, white, grey
Mafic magma/Mafic Rocks • Dark color • High density • Usually form in oceans. • Forms rocks that are black, green, dark grey
There’s always an exception. • The one exception to this rule is obsidian, which is black in color, but felsic in composition.
Learning Targets • I can construct an explanation of how to classify rocks by their formation and how rocks change through geologic processes in the rock cycle.
sedimentary rocks • Form from the weathering of other rocks. • Form from accumulated sediments. • Usually form from material that has been deposited in water. • Sometimes form from wind or ice deposited sediments. • Sometimes retain the characteristics of the sediments from which they form (ex. Layering).
Sedimentary rocks: • Are divided into three categories: • Clastic (fragmental) divided into small parts • Chemical (crystalline) composed of crystals • Organic (bioclastic) (of deposits, esp limestones) derived from shell fragments or similarorganic remains
Clastic rocks • Form from clastic sediment- particles of rock that have been produced by weathering and erosion.
Weathering • the various mechanical and chemical • processes that cause exposed rock to decompose.
Chemical Weathering • Oxygen and acids are agents in chemical weathering.
Chemical sedimentary rocks • Form from materials that were once dissolved in water • Form when water is oversaturated with mineral ions • Often form when the evaporation rate is greater than the rate that fresh water enters a body of water
mechanical Weathering • any of the various weathering processes that cause physical disintegration of exposed rock without any change in the chemical composition of the rock: • Collision between rock surfaces can cause mechanical weathering.
erosion • Erosion happens when a bit of earth material is separated from the surface. Once detached, a force like moving water or wind transports the material to a new location where it is deposited.
Landslides Landslides take place when rock and soil slide down a steep slope very quickly. Landslides can vary in size and in composition. Some landslides may have large boulders while others may have small amounts of rock and soil. Landslides are most common in areas where roads have been cut out in mountainsides or hillsides.
Mudslides A mixture of water, rock, and soil rapidly moves downhill is a mudflow or mudslide. This often occurs after heavy rains. Clay soils can suddenly turn to liquid and begin to flow when conditions are right. Many things can trigger a mudslide: Earthquakes and heavy rain, water reduces friction making once stable rock now loose.
Slump Mass movement known as slump occurs when a mass of rock and soil suddenly slips down a slope. Slump is different from a slide in that the material in a slump moves down in one large mass. Slump often occurs when water soaks the base of a mass of soil that is rich in clay.
Creep Creep is the very slow downhill movement of rock and soil. Creep often results from freezing and thawing of water in cracked layers of rock beneath the soil. Creep can cause trees, poles, fences and other material to have a misshapen appearance.
Sediments become lithified (made into rock) in two steps. • Compaction - as layers of sediment accumulate, the bottom layers are squeezed into a denser mass
Cementation - minerals such as calcium carbonate, iron oxide or silica in groundwater cement compacted grains together.
Clastic sedimentary rocks usually form where a river or stream enters a quiet body of water. • Are often stratified (layered) • May contain fossils
Clastic sedimentary rocks are classified based on the grain size of the sediment they contain.
Organic sedimentary rocks • Form as a result of biological processes. • Can form directly from plant or animal remains (coal and fossiliferous limestone)
Learning Targets • I can classify rocks by their formation and how rocks change through the metamorphic process.
metamorphic rocks • Form as a result of heat, pressure, and chemical activity • Are divided into two groups based on whether they formed from regional or contact metamorphism.
Regional metamorphic rocks • Formed by forces acting over large areas • Formed at extreme temperature and pressure • Form at great depths within the earth’s crust • Form during mountain building due to plate tectonics
contact metamorphic rocks • Form at the interface of hot magma and existing rock • Forms only locally where the minerals are changed by the extreme heat without actually melting
Characteristics of metamorphic rocks • Distortion– a change in the structure of a rock without changing the composition of the rock • Banding or zoning—when minerals become concentrated into bands of different colored minerals (pennies in clay)
