THE ROCK CYCLE
What is the Rock Cycle?
The Rock Cycle
Defined: The process by which all rocks on Earth are formed and how basic Earth materials are recycled over time
Note: A very, very long time
The Rock Cycle
Sedimentary Rock
Metamorphic Rock
Igneous Rock
Three main types of rock on Earth
Igneous Rock: Forms from molten rock that cools and hardens either above or below Earth surface
Two Types: Intrusive/Extrusive Sedimentary Rock: formed either by pieces of
rock being bound together or by chemical precipitation
Two types: Clastic/Non clastic Metamorphic Rock: Form when any type of
rock is altered by the effects of heat, pressure, or chemical action
Two Types: Foliated/ unfoliated
Watch the Video and fill in this Chart! http://www.youtube.com/watch?v=U7YQ5vwaL98
Why does the Rock Cycle even exist?
DENSITY (again) When rock is heated up and melted
inside the Earth, it becomes hot liquid (magma) hot liquids are less dense then solid rock.
The magma moves up through any cracks or openings (volcanoes, fissures) until it reaches the surfaces. Then spreads out, cools, and turns solid.
Why does the Rock Cycle even exist? Cont’d After rock is formed, one of two
things will occur. 1. Rock will begin to erode into
small sediments and settle somewhere else on Earth’s surface (sedimentary)
2. That rock will cool, turn solid, and become more dense, where over a long time period, will begin to sink.
Thus causing a cycle!
Next time we will introduce Igneous Rocks, their formation, and types
IGNEOUS ROCKS Igneous Rock: Forms from molten
rock that cools and hardens either above or below Earth surface.
Igneous rocks are often defined by texture and chemical composition.
Igneous Rocks
Identification of igneous rocks factors Texture: The feel, appearance, or
consistency of a surface or a substance. (Simply what the rock type looks and feels like)
mineral and chemical composition: What minerals does the rock consist
of?
Igneous Rocks
Igneous Rocks are made from volcanic activity and form when magma or lava cools
Magma: Hot molten material INSIDE of the Earth’s surface
Lava: Hot molten material OUTSIDE of the Earth’s surface
MAJOR ELEMENTS PRESENT IN MAGMA
Oxygen, Aluminum, Iron, Magnesium, Calcium, Potassium, and Sodium.
Igneous Rocks by Physical and Chemical Characteristics Intrusive Igneous Rocks: Course-grained igneous rock that
cools slowly beneath the Earth’s surface.
Extrusive Igneous Rocks Fine-grained igneous rocks that cool
quickly on Earths surface overnight
Intrusive Igneous Rock
Cools and turns solid very, very slowly below the Earths surface. Typically have large crystals present in the rock due
to the slow cooling process.
Intrusive Igneous RocksGranite is a coarse-grained, light colored, intrusive igneous rock that contains mainly quartz and feldspar minerals. The specimen above is about two inches (five centimeters) across.
Diorite is a coarse-grained, intrusive igneous rock that contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. The specimen shown above is about two inches (five centimeters) across.
Extrusive Igneous Rocks
Fined grained (smooth) rock that cools quickly on Earth's surface. Cools quickly due to exposure to the atmosphere, interaction with water, etc.
Extrusive Igneous RocksBasalt is a fine-grained, dark-colored extrusive igneous rock composed mainly of plagioclase and pyroxene. The specimen shown is about two inches (five centimeters) across.
Hawaiian Islands
Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. The specimen shown above is about two inches (five centimeters) across.
Identifying Igneous Rock by Color
FELSIC and MAFIC Igneous Rock
Felsic: Light-colored Igneous Rocks. They are light in color due the minerals Feldspar and Silica being present in the mineral
Mafic: Igneous Rocks that are dark in color due to the presence of Magnesium and Iron
Overview of Identification of Igneous RocksIDENTIFICATIO
NDEFINITION EXAMPLE
S
Intrusive Cools and turns solid very, very slowly below the Earths surface. Typically have large crystals present in the rock due to the slow cooling process.
GraniteDiorite
Extrusive Fined grained (smooth) rock that cools quickly on Earth's surface
BasaltObsidian
Mafic Igneous Rocks that are dark in color due to the presence of Magnesium and Iron
ObsidianBasalt
Felsic Light-colored Igneous Rocks. They are light in color due the minerals Feldspar and Silica being present in the mineral
GraniteDiorite
Regents Scheme for Identifying Igneous Rocks
Sedimentary Rocks
2nd most Abundant type of rock in the Earth system.
Sedimentary Rocks
Defined:
Rocks formed either by rock fragments or organic matter being bound together or by chemical precipitation.
Formation of Sedimentary Rock Very cool process Sedimentary rocks formed over millions of
years. The form through a variety of processes beginning with Weathering and Erosion
Step one. Weathering: General process where rocks
are broken down at Earths surface to produce sediment particles
Erosion: The process of individual sediments being carried down hill.
Two Types of Weathering
Physical and Chemical Physical: occurs when solid rock is
broken into smaller pieces by mechanical process that does not change the chemicals in the rock
Chemical: Occurs when the minerals in a rock are chemical altered or disolved
Examples of physical weathering
Examples of Chemical Weathering
Formation of Sedimentary Rock
Weathering occurs when either rain, Ice, wind, or water, breaks down solid rock over time into small, individual sedimentsErosion: Sediments are carried from high energy to low energy areas. Typically occurs by water transporting the sediment down hill. Also by wind.
Transportation and Deposition Step two: Transportation: currents of wind and
water or the moving ice of glaciers transport sediment to new locations down hill or down stream.
Deposition: Occurs when sediment particles settle out as wind dies down, water currents slow, or glacier edges melt.
Step 3: Compaction and Cementation Compaction: Process of sediments
building up in layers on top of each other over time
Cementation: hardening of clastic sediments by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of a sedimentary rock.
Two Main Types of sedimentary Rock Clastic or Non-Clastic Clastic Sedimentary Rock-Made of small pieces
of other types of rocks (igneous, metamorphic, sedimentary). And are cemented together after deposition.
Non-clastic sedimentary rock: Non-clastic sedimentary rocks form from the precipitation (Precipitation is the separating of a solid from a solution) of minerals from ocean water or from the breakdown of the shells and bones of sea creatures.
Examples of Clastic Sedimentary Rock
Sandstone: a clastic sedimentary rock made up mainly of sand-size weathering debris
Conglomerate: a clastic sedimentary rock that contains large rounded clasts. generally filled with smaller particles and/or a chemical cement that binds the rock together.
Shale: a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud".
Examples of Non- ClasticLimestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.Rock Salt is a chemical sedimentary rock that forms from the evaporation of ocean or saline lake waters. It is also known by the mineral name "halite". It is rarely found at Earth's surface, except in areas of very arid climate. It is often mined for use in the chemical industry or for use as a winter highway treatment.
ESRT Scheme for Identifying Sedimentary Rocks
Last but Not Least,Metamorphic Rock Defined: form when any rock is changed by
the effects of heat, pressure, or chemical action.
Two types of Metamorphism Regional or Contact Metamorphic rocks are typically
characterized as: unfoliated or foliated.
Metamorphic Rock Metamorphic rocks form from either Igneous or Sedimentary
rocks that are effected by pressure and heat within the Earths surface.
Metamorphic Rock
New types of Metamorphic rock are formed depending on the amount of heat and pressure present around the rock.
Example: Sedimentary Rock – Shale
Regional Metamorphism
Contact Metamorphism
When molten rock come into contact with local rocks in a small area
Foliated Metamorphic Rocks Foliated Metamorphic Rock Definition: Metamorphic rocks whose
minerals are squeezed together under high pressure and arranged in wavy layers or bands
Examples:
Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains. It typically contains abundant quartz or feldspar minerals. Schist is metamorphic rock with well
developed foliation. It often contains significant amounts of mica which allow the rock to split into thin pieces
Joke of the day….If it looks nice, it is probably Gneiss… If it looks like Schist, it is probably Schist…. Get it???
One more Example….Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by low-grade regional metamorphism
Nonfoliated Metamorphic Rocks Definition: Metamorphic rock that lacks
mineral grains that are banded.
Examples
Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone
Quartzite is a non-foliated metamorphic rock that is produced by the metamorphism of sandstone.