ES Chap 5 & 6: Rocks Objectives 1. Identify and explain characteristics of igneous rocks. This means that if I am given an igneous rock I: a. Can use grain size to identify a rock as intrusive, extrusive, or porphyry. In addition, I can discuss how the rate of cooling is related to grain size. b. Can use color to identify a rock as felsic, intermediate or mafic. c. Combining grain size and color (as described in a & b), I can use Table 5-2 on page 107 to name the rock. d. Use Table 5-2 page 107 to identify a rock if I am given the percent composition of a rock. i. Understand which minerals and rocks in Table 5-2 are high in silica, iron and magnesium. e. Discuss the factors that affect how rocks melt & crystallize f. Describe uses of igneous rocks. g. Rocks that may be samples to identify on the exam: obsidian, pumice, rhyolite, granite, basalt, gabbro. 2. Identify and explain characteristics of sedimentary rocks. This means that I: a. Can describe and list in order the steps that form clastic sedimentary rocks: Weathering (both physical and chemical), erosion, deposition, burial, lithification, cementation b. Can use information about ripple marks and fossils to infer what the past environment is like. c. Can identify a rock into one of the following subgroups; clastic, organic, chemical d. Can use the Law of Superposition to determine which rock layers are older or younger. e. Describe uses of sedimentary rocks. f. Explain miscellaneous terms such as porosity g. Rocks that may be samples to identify on the exam: conglomerate, breccias, sandstone, limestone, coal 3. Identify and explain characteristics of metamorphic. This means that I a. Can identify a rock into a metamorphic subgroup; foliated vs. non-foliated b. Explain the formation of metamorphic rocks. c. You will be asked to identify a rock as metamorphic and then as foliated or non-foliated, but you will not be asked to give it a specific name. 4. Understand how rocks continuously change from 1 type to another in the rock cycle. 5. I can identify a given rock sample into: a. One of the 3 main types of rock described above: igneous, sedimentary or metamorphic. b. Into the appropriate subgroup as described above. Sec 5.1 Classifying Igneous Rock 3 types of Rock: 1. Igneous: Formed from of a. Lava is magma that reaches & flows onto Earth s 2. Sedimentary: Formed from sediments together a. Sediments: Small pieces of 3. Metamorphic: Formed when a rock changes into a due to extreme ES Ch 5 & 6 Rocks Outline - 1-10/14/2012
Igneous Rocks: 1. Extrusive rocks: Fine ( ) grained rocks due to cooling on Earth s a. Examples: 2. Intrusive rocks: Coarse ( ) grained rocks due to cooling the surface Magma: a. Examples: The most common intrusive rock is 1. Composition: a. Mix of rock, gases, and mineral crystals b. Elements common in magma are the major elements found in Earth s crust: c. Most common compound: 2. Types: Based on the amount of Magma Type Amount SiO 2 Relative color of rocks when cools 1. Rhyolitic (Granitic) Special Characteristics 2. Andesitic 3. Basaltic 3. Origin: a. Heat of 800 1200 o C to b. This temperature is found in the and What heats the upper mantle & lower crust? c. Partial Melting is due to minerals with points i. Causes a slushy mix of rock & crystals Section 5.2 Classifying Igneous Rocks 3 Classifications of Igneous Rock: based on the of the rock 1. Felsic 2. Intermediate 3. Mafic ES Ch 5 & 6 Rocks Outline - 2-10/14/2012
Igneous rock type Type of Magma Silica (SiO 2 ) content Relative color Felsic Intermediate Mafic High in: Texture Rock Examples Extrusive Intrusive Main observations for igneous rock identification: 1. Color: vs. 2. Grain size: vs. Special IG rocks: 1. Porphyritic texture: Mixture of grains a. Complex cooling history: 2. Obsidian: Black glass 1. 1 st cooling deep in Earth-forming the crystals. 2. 2 nd cooling of remaining magma due to sudden or close to the surface a. Cooled that crystals are formed: 3. Pumice: 50% holes due to escape of trapped a. Formed from magma b. Used for abrasive polishing mixtures and cleansers Igneous Rocks as Resources 1. Building materials: & to weathering 2. Ore deposits: of substances within the rock a. Gold, silver, lead, & copper are not in compounds that form minerals, but they are found as ES Ch 5 & 6 Rocks Outline - 3-10/14/2012
b. c. Found in or i. Formed when liquid magma fills in other rocks & cools Sec 6.1 Formation of Sedimentary Rocks Steps to Form Sedimentary Rocks: 1. Weathering: Breaking down & of rocks into smaller pieces (called sediments which vary in size) a. Physical or mechanical causes of breakdown include: b. Chemical causes include of rocks by rain or chemicals 2. Erosion: of sediments to a new locations a. Possible means: 3. Deposition: or of sediments on the ground or bottom of bodies of water 4. Burial: Becomes beneath more & more sediments 5. Lithification: means making of and has 2 parts a. Compaction: Bottom layers of sediment are together by of upper sediment layers b. Cementation: Sediments are or together by minerals in the water that c. Summary: Lithification turns into Features of Sedimentary Rocks: 1. Layers (AKA beds) a. Law of : rocks on the if layers are undisturbed i. Exception occurs when layers are overturned by forces b. The following always form on the top of a layer. If they are found on the bottom instead, it indicates that layers have been overturned: 2. Sedimentary rocks usually form in 3. Sedimentary rock is rock on the (not in crust) of Earth a. Igneous rock is the most common rock in the CRUST, but it is buried. Most igneous rock is formed underground, not through lava on surface. ES Ch 5 & 6 Rocks Outline - 4-10/14/2012
Evidence of Past Life 1. Fossils: Preserved of once-living organisms a. Only found in rocks. WHY? b. During lithification, parts of organisms are replaced by & turned into rocks Sec 6.2 Types of Sedimentary Rocks 3 main groups of sedimentary rocks: 1. Clastic 2. Organic 3. Chemical Sedimentary Group Made from Subgroups & examples Clastic sedimentary rock 3 clastic subgroups based on grain size: 1. Coarse-grained: grains or larger a. Due to high water flows & speeds which can carry large pieces: 2. Medium-grained: -sized grains a. Form which has high porosity (incomplete cementation leaves between grains) b. Valuable reservoirs of 3. Fine-grained: a. Low porosity (barrier) Organic Examples: 1. Limestone: 2. : rock from buried swamp plants Chemical Example locations: 1. Coast of or the ES Ch 5 & 6 Rocks Outline - 5-10/14/2012
Importance of Sedimentary Rocks: 1. Fossils tell about a. Type of area and types of organisms: 2. tell the direction of in the past: a. Symmetrical ripple marks: i. Both sides of ripple have same shape ii. Indicates wave action b. Asymmetrical ripple marks: i. 1 side is gently sloped & other side is steep ii. Indicates wind or wave motion iii. Examples: 3. Energy a. b. Reservoir for when (open space) present 4. Limestone to make Sec 6.3 Metamorphic Rocks: rocks turned into a rock type Formation of Metamorphic Rocks 1. Pressure & temp with depth a. If hot enough to melt, rocks are formed b. If not hot enough to melt, but enough to change the rock, rock is made 2. Heat is due to or nearness to intrusions 3. Pressure is due to the pressure of of mountain building 4. Metamorphic rocks may be a. (alternate light & dark bands) due to with i. Lines may be straight or wavy ii. Example: Gneiss is formed from the igneous rock b. i. Example: Marble is formed from the sedimentary rock ES Ch 5 & 6 Rocks Outline - 6-10/14/2012
The Rock Cycle: 1. Is the of rock 2. Based on how new rock type is formed. 3. Following is an example of the possible changes the igneous rock granite could undergo. When it is: a. Weathered into new rock is formed b. Buried (but not melted) where affect it new rock is formed Comparison of the Characteristics of the 3 rock types: ES Ch 5 & 6 Rocks Outline - 7-10/14/2012
Computer Review: http://www.glencoe.com/sec/science/earthscience/index.html a. Chapter Resources b. Unit 2 c. Chapter 5 and Chapter 6 Diagram-Igneous Intrusions #2 ES Ch 5 & 6 Rocks Outline -8-10/14/2012
WS: Rock Record, Figure #1 WS: Rock Record, Figure #2 WS: Rock Record, Figure #3 ES Ch 5 & 6 Rocks Outline - 9-10/14/2012
WS: Rock Record, Multiple Choice Figure ES Ch 5 & 6 Rocks Outline - 10-10/14/2012