RAP 12/17pg 94 What is a rock? What are the three types of rocks?
Topic: Rocks—Chapter 6 6.1 How Rocks Form 6.2 Igneous Rocks 6.3 Sedimentary Rocks 6.4 Metamorphic Rocks
How Rocks Form • In this section, we will be answering two questions: • What is a rock? • What is the rock cycle? ?
What is a rock? =group of minerals bound together.
A. Rock Cycle link
Rock Cycle Diagram • Tape the Rock Cycle onto page 95 in your notebook.
Rocks! Metamorphic Sedimentary Igneous
B. Rock Types 1. Igneous Rocks a. form from crystallization of _____ magma
b. Classification i. Type of magma -Felsic or Granitic or Rhyolitic-rocks are lightcolored and have high silica content - Mafic rocksaredarkcolored, havelower silica
Felsic or Mafic? Mafic ________ http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions/7Rhyolite/RhyoliteCUp.jpg Felsic ________ http://itc.gsw.edu/faculty/tweiland/gabbro.jpg
RAP 12/18 (pg 96) • The rock shown is composed primarily of large crystals that were formed by • Cooling magma c. weathering • Compacting shells d. faulting • What word would describe the type of magma that formed this rock? • Why?
Classifying Igneous Rocks ii. Grain size or texture Extrusive rocks are fine-grained. - - Intrusive rocks are coarse-grained http://core.ecu.edu/geology/harper/igneous/I15lg.gif
Classifying Igneous Rocks • two types: -______________-lava cools quickly on Earth’s surface, small crystals (fine-grained) -________________-lava cools slowly underground, large crystals (coarse-grained) Extrusive Intrusive
Intrusive or Extrusive? ___________________ ________________ volcano.und.nodak.edu/.../volcanic_rocks.html http://cc.usu.edu/~sharohl/glossary.html
What are the two main ways petrologists classify igneous rocks? • If you find a rock that is dark with large grains, what 2 terms would you use to describe it? • If you find a light rock with large crystals, what 2 terms would you use to describe it? • If you find a light rock with small crystals, what 2 terms would you use to describe it?
RAP 1/2 pg. 96Welcome Back! • What two processes would occur to change a metamorphic rock to an IGNEOUS rock? 2.
RAP 1/3 pg. 96 • How do metamorphic rocks form? • What two ways are metamorphic rocks classified? (hint-use your essentials)
2. Metamorphic heat • changed by ___________ and ___________ Types of metamorphism • Regional • Contact • Hydrothermal pressure
1. Regional Metamorphism • affects large regions of the Earth’s crust • most often generated by the compressive forces of mountain building www.gly.fsu.edu/.../ 7_Rocks/7_Rocks_index.htm
3. Hydrothermal Metamorphism 2. Contact Metamorphism • occurs when very hot water reacts with rock. • occurs when solid rock comes in contact with molten rock solid rock, usually from an ________ intrusion. igneous http://enterprise.cc.uakron.edu/geology/natscigeo/Lectures/smrocks/metafig.gif http://www.uoguelph.ca/~sadura/metref/met19.gif
Formation of metamorphic rocks Pressure from the weight of overlying rocks
b. Textures i. Foliated ii. Nonfoliated
i. Foliated • foliated : wavy layers and bands of minerals • high pressure during metamorphism, can cause flat or needle-like crystals to form Gneiss Ex_________: alternating bands of light and dark
Gneiss Rocks! Photo courtesy of Claude G. Genest, University of Quebec at http://www.uqtr.uquebec.ca/relief/Terme/Photo/IMG0054.jpg
Mineral Changes During Foliation Diagram courtesy of Dr. Jürgen Schieber, Indiana University, at http://www.indiana.edu/~geol105/images/gaia_chapter_5/foliation.jpg
Foliation: Slate Photo courtesy of David L. Ozsvath, University of Wisconsin, at http://www.uwsp.edu/geo/faculty/ozsvath/images/slate.jpg
You don’t know schist! Granite schist with garnet porphyroblasts http://www.otago.ac.nz/geology/features/rocks-minerals/schist-gnt.jpg
Schist happens! http://www.gc.maricopa.edu/earthsci/imagearchive/DK_MICA_SCHIST_big.jpg
ii. Nonfoliated -Blocky crystal shapes Example: Quartzite http://www.physci.wsc.ma.edu/young/pgeol/geoinfo/images/rocks/quartzite.jpg
Shale Slate Phyllite Schist
Do Now 12/17 • Using the chart above: • Rocks subjected to high temperature and pressure during metamorphism, can form ______. • What are two possible parent rocks of gneiss? • What does limestone turn into when it undergoes metamorphism?
RAP 1/4 pg. 98 • Schist is a type of _______ metamorphic rock. • Marble is a type of ______ metamorphic rock. • Granite is a type of _______ igneous rock. • Pumice is a type of ______ igneous rock.
3. Sedimentary Rocks a.formed from sediments, dissolved minerals, and/or materials organic
b. Process of formation: i. Weathering -the breaking down of rock into smaller pieces by and processes physical chemical
ii. Erosion -the movement ofsediments
iii. Lithification- process of turning sediments into rock -of sediments by overlying layers squeezed out excess space and water occurs as dissolved minerals cement sediment grains together compaction and cementation
c. Types of Sedimentary Rock • Clastic • Nonclastic
i. Clastic -formed from fragments of other rocks or organic material - classified by size and shapeof fragments Sediment Size Rock Example Conglomerate or breccia Gravel • 2mm 0.063 – 2mm 0.004 – 0.063mm <0.004mm Sand Sandstone Silt Siltstone Clay Shale
Clastic Formation Animation • http://www.classzone.com/books/earth_science/terc/content/visualizations/es0605/es0605page01.cfm?chapter_no=visualization
ii. Nonclastic -form from dissolved minerals coming out of solutionby or -fine-grainedunless they are crystallized precipitation evaporation Limestone (chalk)
RAP 1/7 pg. 98 • What are the two types of sedimentary rocks? • A rock made of pieces of sand would be which type of sedimentary rock?
By the end of class I will… • Be able to use sedimentary, metamorphic and igneous features to describe past environments. • Be able to sort rocks into their rock type based on their characteristics.
Tuff • One other by-product of a volcano is tuff. • Tuff is formed when volcanic ash from a volcano is buried and compressed.
Rock FeaturesA. Igneous i. Dike • A dike is a sheet of igneous rock that cuts across rock layers vertically at a steep angle. • A dike forms when magma intrudes into angled cracks. • A dike can be hundreds of kilometers long, and anywhere from a centimeters to many meters thick.