1 Earth’s Layering
2 Bell work A rock has a MASS of 13.4 gramsThe VOLUME of the rock is 3.6 cm3 What is the DENSITY of the rock? Rank the items from more - less density: Glass, wood, iron, plastic Discuss accuracy of measuring and sig. figs.
3 Vocabulary Mass: the quantity of matter in a body regardless of its volume or of any forces acting on it Volume: the quantity of three-dimensional space enclosed by a closed surface Density: the mass per unit volume = mass/volume
4 Nebular Hypothesis: formation of the solar system
5 The Story so far….. Our solar system belongs to the Milky Way (spiral) Galaxy Solar system formed 4.6 by ago from a nebula. The solar system is heliocentric with the Sun close to the center Planets orbit Sun counter-clockwise in elliptical orbits Planets speed increases as it gets closer to the Sun Earth spins (rotates) on its axis every 24 hours. Polaris the north star is above Earth’s axis and all the stars appear to rotate around it All the planets rotate counter-clockwise except Venus The moon orbits Earth counter-clockwise in 28 days and has a synchronous orbit The moon’s orbit into our shadow or in front of the sun causes eclipses The seasons are due to Earth’s tilt of 23.5° which changes the angle, hours of daylight. Terrestrial planets are near the Sun, evenly spaced and rocky/metallic. The Outer (Jovian) planets are farther from Sun, very spread-out and icy/gassy Jovian planets are larger, have more mass, more gravitational pull and more moons. The planets were “sorted” by gravity and density into the rocky inner planets and the gassy outer planets
6 Earth Essential Question: What materials are INSIDE the Earth?The outside view of Earth as a dynamic changing (not dead) planet. What’s the source of energy that drives our planet? What’s going on inside?
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8 Difference in water level (ml) Peridotite, pyroxene, orInvestigate the Densities of some of Earth’s Rocks. Rock sample Mass (.01g) Volume(before) (0.1 ml) Volume(after) VOLUME Difference in water level (ml) Density; mass/volume (g/cm3) Granite Basalt Peridotite, pyroxene, or olivine Iron meteorite, Magnetite or iron Rocks of different densities found at different depths indicating a “sorting” of materials in the Earth’s rocky crust when it was molten.
9 Earth’s Rocks Lab tips Measure the mass of the rock in grams. Make sure your balance is on grams (g) and zero Fill the graduated cylinder up to 60 ml of water. This is the volume before (write in your chart). Slowly slide the rock down the side of the graduated cylinder. Record the After volume. If needed, dry well before repeat. Subtract After-before volume to get Final Volume. Density of Rock = mass/Final volume Bring your data to the front to get class average
10 Earth’s Layered Structure;As Earth cooled, the materials: rock and metal were “sorted” by density ________________g/cm name _________________ ________________g/cm name ________________ ____________g/cm name ___________ ________________g/cm name _____________
11 Earth’s inner and outer core contain IRON and NICKEL density 7.8 – 8.9
12 How do scientists know that the Earth has different layers? How did they discover this? We know from volcanic activity that there is a layer of molten (melted) magma rock under Earth’s solid surface. Exploring magma
13 Density of Earth’s (surface) Crustal RocksGranite Basalt Peridotite, Olivine Average thickness of Earth’s crust: _______ km Earth’s radius: km What percent of Earth is the crust? _______ %
14 How is a stud finder able to see studs behind the wall?How do bats ‘see’ their prey in the dark? How can you determine what’s inside the Earth when scientists can’t ‘see’ under the surface? How do scientists “SEE” what is inside the Earth?
15 Andrija Mohorovicic 1909 Used seismic waves from earthquakesNoticed a CHANGE IN VELOCITY of waves about 50 km depth Found a boundary between the rocky crust and the magma mantle He discovered the Earth had layers!
16 Seismic Waves Two types of seismic wave behave differentlydepending on the material that they go through Compressional primary or P waves travel and refract through both fluid and solid materials. Shearing secondary or S waves cannot travel through fluids like air or water Fluids cannot support the side-to-side particle motion Travel through solids only Do the classzone.com internet activity questions #3 -#9 on white boards. Discovered the outer, liquid core.
17 Earth Bellringer Question:What do P and S waves tell us about the materials that are INSIDE the Earth? The outside view of Earth as a dynamic changing (not dead) planet. What’s the source of energy that drives our planet? What’s going on inside?
18 P-waves travel through SOLIDS and LIQUIDS S-waves travel through SOLIDS ONLY2 types of ES waves pass through Earth: P-waves: faster compression waves and S-waves: slower snaking waves
19 stop Bent EQ waves behave differently as they move through different density materials. They bend (refraction) or bounce off (reflection) or STOP and don’t go through at all. Bounce off
20 A zone where no waves pass through Earth.Shadow Zone: A zone where no waves pass through Earth. P-waves reappear later, but bent at a different location. S-waves don’t go through at all! There must be a liquid layer below the mantle: A liquid CORE! Shadow zone will help determine the SIZE, diameter of the core.
21 Draw and Label the parts of the Earth on this Diagram!P waves are bent as they pass through the outer core Some P waves actually bounced off! They must have hit a SOLID INNER CORE (Discovered in 1936)!
22 A liquid outer core! molten / melted (liquid) (S-waves don’t pass through) If it is a liquid it must MOVES / FLOWS like a liquid Based on shadow zone, P and S-waves, and magnetic field, we know outer core is liquid iron But liquid what? What material makes up the outer core? How hot is it at the core?
23 What is the Earth’s core made ofWhat is the Earth’s core made of? Let’s look at more Evidence and do the math… Density of Earth’s CRUST: Granite __________ g/cc Basalt ___________ g/cc Peridotite _________ g/cc Average: _________ g/cc Density of crust and mantle Earth’s Average Density: 5.5 g/cc Density of iron: g/cc Density of Nickel 8.9 g/cc 2.6 3.1 3.3
24 Liquid, molten magnetic IRONThe outer core is IRON IRON and NICKEL (alloy) Liquid, molten magnetic IRON Flowing magnetic iron gives Earth’s its magnetic field
25 Velocity of P and S waves change with depth – they move ________Velocity of P and S waves change with depth – they move ________. Now do the Temperature graph!
26 On your POM chart write down what this tells you!Density of Earth’s Material vs. Depth (density is one measure of the PRESSURES exerted by Earth’s layers) On your POM chart write down what this tells you!
27 Bellringer: Name and describe the four parts of the Earth.
28 Is the temperature inside the Earth hot enough to melt iron and nickel?Earth’s internal TEMPERATURES change as depth increases. They __________ This indicates a change in the type of material. Different Layers!
29 Earth’s Internal Heat SourceFor millions of years Earth was bombarded by high velocity meteorites and comets These collisions generated immense amounts of HEAT energy and melted the metals and rock on the young planet. 2. Decaying radioactive rocks in Earth release heat energy. 3. Immense Pressure from the weight of Earth’s layers heat Earth Unlike Moon or Mercury, we are not a dead planet. Earth has internal heat.
30 So….Earth’s 4 layers were determined by physical properties….Temperatures and pressures (both increase and change with greater depth) Physical properties (density, chemicals and elements) 3. Mechanical behavior (how the material moves or doesn’t move: solid or liquid)
31 ACT Science Test Prep QuestionFigure 1 shows that a seismograph located at 125° around the Earth from the earthquake focus would receive which type(s) of seismic waves? A. P-waves only B. S-waves only C. Both P and S waves D. Neither P or S waves 2. According to Figure 1, when P-waves encounter the boundary between the mantle and the core, the P-waves most likely: F. Stop and do not pass into the core G. Enter the core and are refracted H. Change into S-waves J. Change to a third type of wave