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Chapter 22 Earth’s Interior.

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Presentation on theme: "Chapter 22 Earth’s Interior."— Presentation transcript:

1 Chapter 22 Earth’s Interior

2 22.1 Earth’s Structure Scientists can’t see into Earth
We can listen (earthquakes as sound waves) Or, 12 km holes (about 8 miles) can be drilled for use in analysis

3 The Science of Geology Geology- the study of planet Earth, including its composition and structure Geologist study geology Constructive forces vs. destructive forces Constructive forces shape the surface by building mountains, etc. Destructive forces wear away mountains, etc. Uniformitarianism- geologic processes that happen today happened in the past. This was defined by James Hutton in the late 1700’s, a physician and farmer who studied rocks he could only explain if they were older than other people thought, and that they came from other rocks. This means that mountains and canyons happen over a long time.

4 A Cross Section of Earth
Earth has three layers of different density Crust Mantle Core

5 Crust Rocky outer layer Thinnest
Made of silicates (Si and O, maybe Al, Fe, Ca) Two types of crust Continental Less dense Made of granite ~40 km thick Oceanic Dense Made of basalt 7 km thick

6 Mantle Thick layer of hot, solid rock 2850 km
P and T increase closer to the core Silicates, Fe, Mg Three layers Lithosphere- cool, rigid rock, uppermost layer, 100 km thick Asthenoshpere- softer, weaker rock, taffy-like motion Mesosphere- stronger rock nearest core

7 Core Fe, Ni 3.6 million times normal pressure 5500 degrees Celsius
Outer core- high T, liquid metal, magnetic and electric current source Inner core- high P, solid

8 22.2 Minerals Emeralds green from Cr
Rock- solid combination of minerals or mineral materials Mineral- naturally occurring, inorganic solid with crystal structure and characteristic chemical composition Inorganic- not made from living things (coal is organic since it’s from plants) Concrete is not a mineral- man-made Minerals are the building blocks of rocks 4,000 minerals, but only a few are common, like quartz, feldspar, mica, hornblende (granite) Crystal- repeating pattern of atoms

9 Properties of Minerals
Crystal structure Color Streak Luster Density Hardness Fracture Cleavage

10 Crystal Structure Geometric shape
Some large, some small crystals, but all same shape for a certain mineral Prisms, cubes, sheets, needles, threads Halite (table salt) is cubic Garnet (Jan.) is 12 sided (octahedral)

11 Color Pyrite (fool’s gold) is golden yellow Sulfur is yellow
Quartz can take in different chemicals and be different colors

12 Streak Color of mineral’s powder Scrape on porcelain, or streak plate
Not always same as color of mineral Hematite (black) has a red streak

13 Luster Way mineral reflects light Shiny
Galena and pyrite metallic luster Sulfur resinous-to-greasy luster Rough is called earthy Silky, pearly, vitreous (glassy)

14 Density D = m/v High atomic mass means high density P. 667 table
We’ll do calculations in lab experiments

15 Hardness Resistance to scratching Hard scratches soft
Mohs hardness scale 1-10 Talc to diamond Fingernail is 2.5

16 Fracture and Cleavage Fracture is a break, some are even, some not
Cleavage is an even break Graphite (pencils) Glass (uneven)

17 22.3 Rocks and the Rock Cycle
3 types of rocks Igneous- formed from magma (molten rock and gases) which turns into lava. The rock occurs when it cools. Intrusive rocks are coarse and large. Extrusive are smooth, small. They are usually dark in color. Sedimentary- made from weathered or broken rocks, found in oceans, lakes, streams, deserts Clastic- broken pieces held by cement Chemical- chemical reactions, like evaporation or acid rain Organic- ex. coral Metamorphic- changes form, P or T. Particles lined up maybe bands (foliated rock) Rock cycle

18 22.4 Plate Tectonics Theory that lithosphere moves slowly on asthenosphere. Continental drift (Earth as puzzle) Alfred Wegener and Pangaea Mid-ocean ridge- underwater mountains Sea-floor spreading- process by which new oceanic crust is created at mid-ocean ridges as older crust moves away Subduction- plates sink into mantle Trench- depression Evidence of movement of mantle (magnetic stripes)

19 Plate Boundaries Divergent- plates move away, magma flows
Convergent- plates come together, mountain Transform- plates slide past (earthquake)

20 22.5 Earthquakes Earthquake- movement of lithosphere that occurs when rocks in lithosphere suddenly shift, releasing stored energy in vibrations called seismic waves Caused by stress in plate movement Fault- break in a mass of rock along which movement occurs ex. San Andreas Fold- a bend in layers of rock Focus- center of earthquake beneath Earth Epicenter- center of earthquake on Earth’s surface P waves- longitudinal waves like sound waves (accordion), first detected S waves- transverse waves, can’t travel through liquid Surface waves- when seismic waves reach Earth’s surface, slower than P and S, but larger ground movement Measured by seismograph using Richter Scale (most well known), Moment Magnitude Scale (best), or Modified Mercalli Scale (observations)

21 22.6 Volcanoes Volcano- mountain that forms when magma reaches the surface Most inactive Like a soda bottle Magma goes from magma chamber, to pipe, to vent, or opening Top is called a crater, unless collapsed, which is a caldera Quiet if very hot, low in silica; high silica is loud Most on plate boundaries (Ring of Fire) Hot spot- region where hot rock extends from deep within the mantle to the surface

22 Types of Volcanoes Shield- quiet, wide, flat
Cinder Cone- ash and cinder, steeple Composite- explosive (traditional), lava and ash

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