Earth's Structure and Processes (PDF)

Lesson 2 The Earth Copyright © 2020 by W. W. Norton & Company, Inc. Earth’s Magnetic Field ▪ Earth is surrounded by a magnetic field like a bar magnet. ▪ This is what causes your compass to point north. Figure 1.12b The Magnetosphere ▪ This region is protected by the Earth’s magnetic field. ▪...

Lesson 2 The Earth Copyright © 2020 by W. W. Norton & Company, Inc. Earth’s Magnetic Field ▪ Earth is surrounded by a magnetic field like a bar magnet. ▪ This is what causes your compass to point north. Figure 1.12b The Magnetosphere ▪ This region is protected by the Earth’s magnetic field. ▪ Solar wind is mostly deflected around the magnetosphere. ▪ The solar wind contains charged particles, electrons and proton, travelling at over 1.6 million kilometers per hour ▪ Cosmic rays are high energy radiation from outer space that strike atmospheric particles and produce muons ▪ Van Allen radiation belts is where solar wind and cosmic ray particles are trapped and held that aren’t deflected from the weaker outer magnetic field of the Earth. (640 km to 58 000 km from the Earth) ▪ Particles flowing down to poles generate the aurora (northern lights). Figure 1.12c Earth’s Atmosphere ▪ Layer of gas that surrounds the Earth ▪ Primarily nitrogen (78%) and oxygen (21%) ▪ Creates air pressure on surroundings ▪ Space craft orbit at 400 km where there is very little friction due to air molecules Figure 1.14 Lower Atmosphere ▪ Clouds: tiny water droplets or ice crystals suspended in the lower atmosphere ▪ Wind: Wind speeds generally decrease closer to the ground. ▪ 1 – 50 km/h near the ground at 9-16 km, winds increase in speed Figure 1.15 The Hydrosphere and Cryosphere ▪ Hydrosphere: all of the Earth’s water • Covers about 70% of surface • About 97% is salt water (3.5 % dissolved salt), and the remainder is fresh. • Only 3% is freshwater and of this less than 1% is readily available for consumption which is ground water. ▪ Cryosphere: glaciers and permafrost (snow and ice) Figure 1.16 Materials of the Geosphere ▪ The solid Earth: • 92 naturally occurring elements are all found on Earth. • Four (iron, oxygen, silicon, and magnesium) make up 90% of the Earth’s solid mass. Figure 1.17 Basic Categories of Materials—1 ▪ Melt or Molten Material: melted rock ▪ Glass: solid with no orderly arrangement of atoms ▪ Mineral: naturally occurring substances with a crystalline structure Figure 1.18a Basic Categories of Materials—2 ▪ Sediment: accumulation of loose grains ▪ Metal: metallic elements (have specific properties) ▪ Rock: igneous (solidification of molten material), sedimentary (cementing together of solid material), metamorphic (rocks undergoing change in the earth due to increase temperature and pressure) Figure 1.18b The Surface of the Geosphere ▪ Bathymetry: variation in sea floor depths (average depth of 4 km) ▪ Topography: variations in elevation of the land (average elevation is 0.8 km) Most of land lies in large areas called continents which are over 8000 km across and the remainder occurs in smaller areas known as islands The land surface contains plains, plateaus, mountain rangers, valleys volcanoes The land surface contains exposed rock, sediment and some has become soil Processes on the Earth change its appearance making it a dynamic planet unlike the other terrestrial planets Figure 1.19 The Biosphere ▪ Where life exists ▪ Organic chemicals produced by living organisms ▪ Extends up from the surface and down below the surface for several kilometers ▪ Humans have made changes on the planet (anthropogenic change) Earth’s Interior ▪ Layered interior: • Core • Mantle • Crust ▪ Moho: the boundary between crust and mantle ▪ Deepest hole dug- 12. 3 km or 0.2 % of Earth’s radius ▪ Rocks in the interior are more dense than those near surface ▪ Layers of Earth resemble a hard boiled egg with different densities ▪ Basalt and gabbro are grey, dense igneous rock, basalt contains tiny crystals, gabbro coarser crystals Figure 1.22b, Table 1.1 Refining the View ▪ Seismic waves (earthquake waves) give a more detailed picture: • Inner and outer core- inner core is solid (mixture of iron, 4% nickel, and 10 % oxygen, silicon, or sulfur), outer core is molten and produces the magnetic field • Upper mantle from the Moho to a depth of 660 km, the bottom portion of the upper mantle, between 410 km to 660 km is known as the transition zone because there are changes in the minerals in the peridotite take place, nearly all the mantle is solid but some is fluid (soft but not liquid wax) and can flow at less than 15 cm per year and is know as plastic flow • Crust (oceanic and continental) Figure 1.23b The Crust Figure 1.23b Class Questions Class Question 1 What are the two most common gases found in the Earth’s atmosphere? a. nitrogen and oxygen b. oxygen and carbon dioxide c. nitrogen and argon d. argon and oxygen e. carbon dioxide and water vapor Class Question 1 Answer What are the two most common gases found in the Earth’s atmosphere? a. nitrogen and oxygen (answer) b. oxygen and carbon dioxide c. nitrogen and argon d. argon and oxygen e. carbon dioxide and water vapor Class Question 2 The Earth’s _____ protects us from electrically charged particles of the solar wind. a. atmosphere b. cryosphere c. magnetosphere d. hydrosphere e. heliosphere Class Question 2 Answer The Earth’s _____ protects us from electrically charged particles of the solar wind. a. atmosphere b. cryosphere c. magnetosphere (answer) d. hydrosphere e. heliosphere Class Question 3 Which is the thinnest layer of the Earth? a. upper mantle b. inner core c. lower mantle d. continental crust e. oceanic crust Class Question 3 Answer Which is the thinnest layer of the Earth? a. upper mantle b. inner core c. lower mantle d. continental crust e. oceanic crust (answer) Class Question 4 Earth’s hottest layer is its a. crust. b. mantle. c. asthenosphere. d. core. Class Question 4 Answer Earth’s hottest layer is its a. crust. b. mantle. c. asthenosphere. d. core. (answer) Think-Pair-Share Class Question What types of geosphere materials do you interact with on a daily basis? How? Textbook Questions Page 47 #9-19, 22