Unit 4 – Inside Earth
OVERVIEW - Surface and subsurface processes that are involved in the formation and destruction of earth materials are identified in this unit.
Standard for this unit
Students will investigate the scientific view of how the earth’s surface is formed.
Compare and contrast the Earth’s crust, mantle, and core including temperature, density, and composition.
Recognize that lithospheric plates constantly move and cause major geological events on the earth’s surface.
Explain the effects of physical processes (plate tectonics, erosion, deposition, volcanic eruption, gravity) on geological features including oceans (composition, currents, and tides).
Students will investigate the scientific view of how the earth’s surface is formed.
Describe how fossils show evidence of the changing surface and climate of the Earth.
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Questions – students will be asked to answer these during this unit of study
#1 How are the earth’s layers alike and different?
#2 What challenges stand in the way of sending explorers to the center of the earth?
#3 How does the movement of lithospheric plates cause major events on earth’s surface?
#4 What evidence do scientists have that continents were once joined together?
#5 Why do mountains often occur in ranges thousands of kilometers long?
#6 What can fossils tell us about movements of the plates in the past?
1. Draw a picture of Earth’s layers.
2. The earth is layered with
CORE metallic, inner core is solid, outer core is molten
MANTLE solid but is hot enough to flow
LITHOSPHERE made of crust and uppermost mantle
3. Each layer differs in composition, density, and temperature.
4. The spinning of the inner core of Earth is responsible for the Earth’s magnetic field.
Complete the chart.
Layer / Composition / Density / TemperatureCORE - Inner / Nickel & iron (solid) / 12.6 – 13.0 g/cm3 / 5000 C
CORE - outer / Iron & Nickel (liquid) / 9.9 – 12.2 g/cm3 / 4400 – 5000 C
MANTLE - Asthenosphere / Silicon, oxygen, iron, & magnesium / 3.3 – 5.7 g/cm3 / 870 - 2200 C
Lithosphere (upper Mantle and Crust)
CRUST – Continental / Granite & oxygen, silicon, aluminum, calcium, iron, sodium, potassium, & magnesium / 2.7 g/cm3 / 0 - 870 C
CRUST - Ocean / Basalt / 3.0 - 3.3 g/cm3 / 0 - 870 C
5. Temperature and density increases as depth increases.
6. The composition of the earth changes with depth and layers.
7. The crust is the upper part of the rigid lithosphere and is of different composition under land as opposed to the ocean floor.
8. The two types of crust are the oceanic crust which is more dense and it is made primarily of basalt. The continental crust is made up mainly of granite.
9. Why is there different density between the types of crust? The oceanic crust is squeezed by the immense pressure of the ocean above and the granite is transformed into basalt.
10. The Lithosphere is the coolest layer of the earth.
11. Below the rigid lithosphere, the mantle consists of hot rock of tar-like consistency, which slowly moves or flows.
12. The lithosphere is the smallest layer of the Earth and it comprises 1% of the Earth’s total mass.
13. The mantle comprises 66% of the Earth’s total mass.
14. The core is the hottest layer of the Earth and together they represent 33% of the Earth’s total mass.
15 The outer core is molten and the inner core is a dense solid.
Moving plates
16. Hot rocks rising and falling in the mantle/asthenosphere is called convection.
17. Heat from the mantle and core creates convection currents.
18. Lithospheric plates on the scales of continents and oceans constantly move.
19. The lithosphere is divided into separate plates which move very slowly in response to the mantle.
20. Plate movement causes major geologic events such as volcanoes, earthquakes, and mountain formation.
21. The theory of plate tectonics connects the evidence for the formation, movement, and destruction of the plates.
Boundaries
22. At the edges or boundaries of the plates, the earth's crust is in motion.
23. Three type of boundaries
Divergent (Move apart)
Convergent (push together)
Transform (slide past each other)
24. At divergent plate boundaries such as the mid-Atlantic ridge, new ocean floor is created.
25. At convergent plate boundaries known as subduction zones, a trench and deep earthquakes mark the zone where a slab of oceanic lithosphere descends into the mantle, and volcanoes and mountain ranges form on adjacent land.
26. When continental crust meets continental crust at a convergent boundary, a collision occurs, resulting in folds, faults, and high mountains.
27. Transform boundaries are where plates slide past each other. They connect other plate boundaries and are characterized by earthquakes.
Earthquakes
28. Earthquakes occur in the lithosphere.
29. Geologists analyze earthquake waves (seismic waves) to determine the composition of the layers within Earth.
30. A machine that measures earthquakes is called a seismograph and the picture that this machine draws is called a seismogram.
31. The focus is the exact location where an earthquake begins while the epicenter is the spot on the Earth’s surface immediately above where the earthquake hit.
32. There are 3 main types of earthquake waves: S wave, P wave, and Surface wave
33. The P wave is the fastest wave and the least destructive.
34. The Surface wave is the slowest wave and the most destructive.
35. S waves are blocked by liquid. Since seismographs on the opposite side of the Earth do not receive any S waves after an earth quake so scientists have concluded that the Earth has a liquid layer
36. A shadow zone is formed on the opposite side of the Earth from where the earthquake occurred because S waves are blocked by liquid.
37. The Richter scale measures the strength of earthquakes. A 5.0 earthquake is approximately 32 times stronger than a 4.0 earthquake.
38. The speed of seismic waves depends on the density of the layer through which they travel.
39. The best thing to do when an earthquake occurs …
Inside a building - immediately hide under a desk or chair
Outside – move away from buildings
Changes on Earth
40. The mantle is solid but capable of flow (like hot asphalt or fudge). Under special conditions like at hot spots and along plate boundaries the mantle or crust melt to make magma, which may then rise to the surface to make a volcanic eruption.
41. Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.
42. Some changes in the earth’s surface are abrupt, such as earthquakes and volcanic eruptions, while other changes happen very slowly such as uplift and wearing down of mountains.
43. Moving plates cause major changes in a world map over tens of millions of years.
44. Pangaea was the most recent of a succession of supercontinents that have formed and broken up over time.
45. Earthquakes represent sudden breaks in crust continuously stressed by plate movement. Gradually over time, the same movements result in major crustal features.
Vocabulary
1. Seismograph - a machine that measures earthquakes
2. Seismogram - the picture that this machine draw
3. Richter scale - a numerical scale for expressing the magnitude of an earthquake on the basis of seismograph oscillations.
4. Focus - the exact location where an earthquake begins
5. Epicenter - the spot on the Earth’s surface immediately above where the earthquake hit
6. Shadow zone - the area of the earth that does not receive any direct seismic waves from an earthquake.
7. Lithosphere – is made of crust and uppermost mantle
8. Asthenosphere - the upper layer of the earth's mantle, below the lithosphere
9. Plate Tectonics - a theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates that move slowly over the underlying mantle
10. Magma - hot fluid or semi fluid material below or within the earth's crust.
11. Continental Drift –a theory explaining the gradual movement of the continents across the earth's surface through geological time
12. Convection currents – currents in the mantle caused by the movement of fluid by the tendency of hotter and therefore less dense material to rise, and cooler, denser material to sink under the influence of gravity, which consequently results in transfer of heat
13. Subduction - the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate
14. Faults - a crack in the earth's crust
15. Rifting – to tear or force something apart
16. Earthquake - a sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action
17. Volcano - a mountain or hill having a crater or vent through which lava, rock fragments, hot vapor, and gas erupt from the Earth's crust