© 2014 Pearson Education, Inc. Chapter 2 Lecture McKnight's Physical Geography Lectures Chapter 13 An Introduction to Landform Study Modified by AJ Allred for Geography 1000 Salt Lake Community College Fall 2013 © 2014 Pearson Education, Inc. Andrew Mercer Mississippi State University

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Describe the internal structure of Earth. Describe Earth's magnetic field. Define mineral, and explain why they are important. Describe quartz, and explain its importance. Differentiate between rock, bedrock, outcrop, and regolith. Identify the three rock classes or families, and explain how they form. Explain the classification of igneous rocks.

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Describe igneous rock textures, and explain their relationships to magma and lava and the terms intrusive and extrusive. Identify and describe four intrusive igneous rocks and six extrusive igneous rocks. Explain the classification of sedimentary rocks. Explain the structure of sedimentary deposits. Identify and describe four detrital (clastic) sedimentary rocks and four chemical and organic sedimentary rocks. Explain the classification of metamorphic rocks. Explain the three types of metamorphism.

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Explain "fracking." Identify and describe four foliated metamorphic rocks and four non-foliated metamorphic rocks. Explain the rock cycle and its significance. Differentiate between the continental and oceanic rocks. Explain isostasy and its significance. Define topography, landform, and geomorphology. Explain how structure, process, slope, and drainage act together to shape the landscape. Differentiate between internal and external geomorphic processes.

© 2014 Pearson Education, Inc. The Structure of Earth Understanding of Earth's structure based on inference Four (three) regions of Earth's interior

© 2014 Pearson Education, Inc. The Structure of Earth Crust –Depth of 5 km below ocean to near 20 km below land –Less than 1% of Earth's volume, 0.4% of Earth's mass Mantle –Extends to depth of 2900 km (1800 miles) –Largest of four shells –Makes up 84% of total volume, 67% of total mass –Three sublayers Lithosphere Asthenosphere Rigid rocks – lower mantle

© 2014 Pearson Education, Inc. The Structure of Earth Outer core –Molten, extends to depth of 5000 km Inner core –Dense mass with radius of about 1450 km –Primarily made of iron/nickel or iron/silicate –Two zones combined make up 15% of Earth's volume and 32% of Earth's mass –Magnetic field of Earth controlled by outer core –Magnetic poles not the same as the axial poles Plate tectonics and the structure of Earth “Continental drift” Plate tectonics – continental-sized plates slide along the asthenosphere

© 2014 Pearson Education, Inc. The Composition of Earth Minerals – naturally formed compounds and elements of Earth Mineral characteristics –Solid –Found in nature –Inorganic –Specific chemical composition –Contains atoms that arrange in patterns to form crystals Silicon-based – sandy sediment “cooked” (metamorphed) into a new crystal

© 2014 Pearson Education, Inc. The Composition of Earth Important crustal minerals –Silicates – combine oxygen and silicon, the most common elements in the lithosphere –Oxides – elements that are combined with oxygen –Sulfides – sulfur and another element

© 2014 Pearson Education, Inc. The Composition of Earth Important crustal minerals (cont.) –Sulfates – contain sulfur and oxygen –Carbonates – light-colored minerals that are composed of a combination of carbon, oxygen and an element (e.g., limestone) –Halides – derived from word “salt,” salty minerals –Native elements – gold and silver

© 2014 Pearson Education, Inc. The Composition of Earth 100 important native elements combine to make 4,400 important mineral compounds Fewer than 20 minerals make up 95% of the composition of crustal rocks –Bedrock –Regolith –Soil Oxygen, iron, calcium, sulfur, silicon, carbon, aluminum, magnesium, lithium, titanium, etc.

© 2014 Pearson Education, Inc. The Composition of Earth The three classes of rocks Igneous Sedimentary Metamorphic

© 2014 Pearson Education, Inc. The Composition of Earth Igneous rocks –Igneous – “fiery inception” –Magma – molten rock beneath Earth's surface –Lava – molten rock when it flows onto Earth's surface –Pyroclastics –Classification of igneous rocks is based on mineral composition and texture –Texture based on how rocks cool

© 2014 Pearson Education, Inc. The Composition of Earth Two types of igneous rocks –Plutonic (intrusive) Rocks cool beneath Earth's surface Surrounding rocks insulate the magma intrusion, slowing cooling Individual minerals in a plutonic rock can grow to large size Granite

© 2014 Pearson Education, Inc. The Composition of Earth Two types of igneous rocks (cont.) –Volcanic (extrusive) Form on Earth's surface Cool rapidly Generally do not show individual mineral crystals, but can if the crystals are formed from shattered rock that was explosively ejected Basalt

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Sedimentary Rocks –External processes cause rock disintegration –Material transported by water as sediment –Over long periods, large amounts of sediment build to large thicknesses –Exert enormous pressure that causes particles in sediment to interlock –Chemical cementation takes place –Strata – horizontal layers of sedimentary rock; sometimes tilted into vertical by Earth processes

© 2014 Pearson Education, Inc. Sedimentary rock Slightly more durable cap rock protects these features for a few “minutes” longer. Arches National Park Layered, cemented ‘dust’

© 2014 Pearson Education, Inc. The Composition of Earth Two primary types of sedimentary rocks –Clastic Composed of fragments of preexisting rocks Shale is an example (may host oil, gas, coal in ‘dust’ layers) Conglomerate; composed of pebble-sized fragments –Chemical and organic sedimentary rocks Formed by precipitation of soluble materials or complicated chemical reactions Limestone and coal are examples Organic sedimentary rocks such as coal form from remains of dead plants and animals

© 2014 Pearson Education, Inc. The Composition of Earth The two primary types of sedimentary rocks; white rock is limestone, dark rock is shale

© 2014 Pearson Education, Inc. Metamorphic Rocks –Rocks that were originally igneous or sedimentary and have been changed by heat and pressure –“cooking” of rocks “morph” into something different –Rearranges the crystal structure of the original rock –Contact metamorphism – rock contacts magma and is rearranged –Bones and shells (low in organics) turn into gypsum or chalk  limestone  marble –sandstone becomes quartzite (sort of like glass)

© 2014 Pearson Education, Inc. The Composition of Earth Schist – metamorphic rocks with narrow foliations Gneiss – broad, banded foliations

© 2014 Pearson Education, Inc. The Composition of Earth The rock cycle – processes where rocks can transition between the three rock types Chicken or egg? “scissors,paper, rock”

© 2014 Pearson Education, Inc. Continental and ocean floor rocks –Sedimentary rocks make up 75% of the continents –Continental crust – sial (silicon and aluminum) –Ocean floor crust – sima (silicon and magnesium) –Ocean crust can be subducted into the athenosphere

© 2014 Pearson Education, Inc. The Composition of Earth Isostasy – push crust down in one place – it pushes back up in another

© 2014 Pearson Education, Inc. –Internal – originate from within Earth, increase relief of land surface –External – originate from sources above the lithosphere, such as the atmosphere or oceans; decrease relief of land surface Both are energized by different forms of radioactivity