Geosphere

The lithosphere is the solid, outer part of the Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure. It is bounded by the atmosphere above and the asthenosphere (another part of the upper mantle) below.

The lithosphere is the most rigid of Earth’s layers. Although the rocks of the lithosphere are still considered elastic, they are not viscous (able to flow). The asthenosphere is viscous, and the lithosphere-asthenosphere boundary (LAB) is the point where geologists and rheologists—scientists who study the flow of matter—mark the difference in ductility between the two layers of the upper mantle. Ductility measures a solid material’s ability to deform or stretch under stress. The lithosphere is far less ductile than the asthenosphere. The elasticity and ductility of the lithosphere depends on temperature, stress, and the curvature of the Earth itself.

The lithosphere is also the coolest of Earth’s layers. In fact, some definitions of the lithosphere stress its ability to conduct heat associated with the convection taking place in the plastic mantle below the lithosphere.

There are two types of lithosphere: oceanic lithosphere and continental lithosphere. Oceanic lithosphere is associated with oceanic crust, and is slightly denser than continental lithosphere. Continental lithosphere, associated with continental crust, can be much, much thicker than its oceanic cousin, stretching more than 200 kilometers (124 miles) below Earth’s surface.

The following concepts that pertain to the lithosphere will be explore in greater depth:

• Earth's interior structure​
• Pangaea
• plate tectonics
• earthquakes
• volcanoes
• the rock cycle
• weathering, erosion, and deposition
• soil formation, texture, and conservation

Earth's Interior Structure

Earth was formed about 4.6 billion years ago. It has a diameter of about 7,972 miles (12,756 km). The Earth's interior consists of rock and metal that is structured in layers. Both temperature and pressure increase from the crust to the core.

Crust = Hard and rigid, it's the earth's outermost and thinnest layer, only 3 to 5 miles thin (5 km - 10 km) under the oceans and 20 to 30 miles (30 - 50 km) thin under the continents. The oceanic crust is primarily composed of basaltic rock while the continental crust is primarily composed of granitic rock.

Lithosphere = Made up of the crust and a tiny bit of the upper mantle, this layer is divided into several constantly (very slowly) moving plates of solid rock that hold the continents and oceans.

Astheosphere = The plates of the lithosphere move (or float) on this hot, malleable semiliquid (plastic-like) zone in the upper mantle, directly underneath the lithosphere.

Mantle = Subdivided into two regions, upper and lower, this dense layer made of hot, semisolid rock is located directly below the crust and is about 1,800 miles (2,900 km) thick. The mantle is primarily composed of silicate rock that is rich in iron and magnesium relative to the overlying crust. Although solid, the high temperatures within the mantle cause the silicate material to be sufficiently ductile that it can flow on very long timescales. Convection of the mantle is expressed at the surface through the motions of tectonic plates.

Outer core = The outer core is the only liquid layer of the earth – a sea of mostly iron and nickel. It is roughly 1,800 to 3,200 miles (2,890 to 5,150 km) below the surface and about 1,400 miles (2,300 km) thick. and has a temperature around 5000 °C. This is where the Earth’s magnetic field is generated. Electrical currents flow in the nickel iron fluid. These electrical currents create the Earth’s magnetic field. This magnetic field extends outward from the Earth for several thousand kilometers. This magnetic field acts like a force field; a magnetic bubble around the Earth. It deflects the Sun’s solar wind. Without this field, the solar wind would directly strike the Earth’s atmosphere. This could have slowly removed the Earth’s atmosphere, rendering the Earth nearly lifeless, which is what happened long ago on Mars.

​Inner core = An extremely hot, solid sphere of mostly iron and nickel at the center of the earth. It is 3,200 to 3,960 miles (5,150 to 6,378 km) below the surface and about 750 miles (1,200 km) in diameter. It is very hot, about 5,400 °C (9,800 °F). It is still hot after all this time because it contains radioactive elements which were created in a supernova explosion before the earth formed. It is heat from this radioactive decay that has prevented the Earth’s core from cooling. When the Earth’s core finally does cool, billions of years from now, then Earth will eventually solidify.

Pangaea

Pangaea (also spelled Pangea) was a supercontinent that incorporated almost all the landmasses on Earth. Pangaea was surrounded by a global ocean called Panthalassa and it was fully assembled by the Early Permian Period (some 225 million years ago). The supercontinent began to break apart about 200 million years ago, during the Early Jurassic Period (about 135 million years ago), eventually forming the modern continents and the Atlantic and Indian oceans. Pangaea’s existence was first proposed in 1912 by German meteorologist Alfred Wegener as a part of his theory of continental drift. Its name is derived from the Greek pangaia, meaning “all the Earth.”

PLATE TECTONICS

Introduction: Plate tectonics is the theory that Earth’s rigid outer layer, known as the lithosphere overlies the plastic-like layer of the mantle called the asthenosphere. The lithosphere is broken up into about a dozen large “plates” and several small ones. These plates move relative to each other, typically at rates of 5 to 10 cm (2 to 4 inches) per year, and interact along their boundaries, where they converge, diverge, or slip past one another. Such interactions are thought to be responsible for most of Earth’s seismic and volcanic activity, although earthquakes and volcanoes are not wholly absent in plate interiors. Plate motions cause mountains to rise where plates push together, or converge, and continents to fracture and oceans to form where plates pull apart, or diverge. The continents are embedded in the plates and drift passively with them, which over millions of years results in significant changes in Earth’s geography.

Learning Objectives: Upon completion of this section you will be able to:

• pinpoint location throughout the world using latitude and longitude coordinates
• draw, label and explain the characteristics of Earth's interior layers
• justify the theory of Pangaea and "continental drift"as put forth by Alfred Wegener
• justify the theory of "seafloor spreading" as put forth by Harry Hess
• identify the primary plates that comprise Earth's lithosphere and explain how they interact with one another at their boundaries
• analyze maps of tectonic plates to determine the effect of their interaction with one another

Essential Question: How does the theory of plate tectonics help us to understand the dynamics of Earth's lithosphere?

Key Vocabulary: crust, mantle, outer core, inner core, asthenosphere, Pangaea, continental drift, seafloor spreading, ocean trench, subduction, slab pull, ridge push, mantle convection, rift valley, hot spot,convergent boundary, divergent boundary, transform boundary, Ring of Fire, buoyant, Glossopteris, Mesosaurus, Lystrosaurus, Cynognathus, fault, mid-ocean ridge, isochronic map, magnetic reversal, sonar, Harry Hess, Alfred Wegener.

Watch "Colliding Continents" while completing the Colliding Continents Video Notes.

Use the PowerPoint above to complete the Continental Drift and Plate Tectonics Notes.

Use the PowerPoint above to complete your Plate Boundaries Notes.

Plate Tectonics Videos: You will find the three videos below to be very help in understand how tectonic plates move in response to one another. You will also learn some exciting facts about plate tectonics both past and future by watching the first video. You need to watch the first video and any one of the other two videos.

Complete the "Know Your Boundaries" Worksheet

Hot spots are another factor by which we understand the dynamics of plate tectonics. They do not form at plate boundaries, but in the interior of a plate. They are relatively stationary, large plumes of magma underneath plates. As a plate moves very slowly over the hot spot, the magma seeps through a opening in the Earth's crust and form a volcano. If on the bottom of the ocean, then the volcano can become so large that it breaks the surface of the ocean and forms an island. Over tens of thousands of years a chain of islands may form. The Hawaiian Islands were formed this way and there is a hot spot under Yellow Stone National Park. The video below will help you to better understand how hot spots form island chains.

Using the PowerPoint below, complete your Faults and Folds Notes

We will complete the Candy Tectonics Lab in Class.

Complete the Crustal Plates Lab. Plot each volcanic point in blue on the map, and each earthquake epicenter in red on the map. Answer the analysis questions when finished.

Earthquakes

Introduction: An earthquake occurs when two tectonic plates suddenly slip past one another and thus releasing energy in the form of seismic waves. The surface where they slip is called the fault or fault plane. The location below the earth’s surface where the earthquake starts is called the focus or hypocenter, and the location directly above it on the surface of the earth is called the epicenter. They strike suddenly and violently and can occur at any time, day or night, throughout the year. Smaller earthquakes might crack some windows and shake products off store shelves, but larger earthquakes can cause death and massive destruction, devastating communities and debilitating local economies.

Essential Question: How do earthquakes help us to better understand the dynamics of Earth's lithosphere.

Key Vocabulary: amplitude, aftershocks, Benioff zones, compressional waves, crest, ductile deformation, elastic deformation, epicenter, fault, focus, hypocenter, intensity, Love wave, normal fault, primary wave, refraction, Ritcher scale, Rayleigh wave, reflection, reverse fault, Ring of Fire, secondary wave, seismic wave, shadow zone, stress, strain, strike-slip fault, seismograph, seismometer, surface wave, tension stress, trough, tsunami, wavelength, etc.

Using the PowerPoint below complete your Earthquake Notes.

Seismic Waves

Seismic Waves: When an earthquake occurs, the elastic energy is released and sends out vibrations that travel in all directions throughout the Earth. These vibrations are called seismic waves. Click on each illustration below to view the motion of the wave.

Complete the Integrated Science: Locating Earthquake Epicenters Activity

Volcanoes

Introduction: Volcanoes are awesome manifestations of the fiery power contained deep within the Earth. These formations are essentially vents on the Earth's surface where molten rock, debris, and gases from the planet's interior are emitted. The mountain-like mounds that we associate with volcanoes are what remain after the material spewed during eruptions has collected and hardened around the vent. This can happen over a period of weeks or many millions of years.

Essential Question: How do volcanoes help us to better understand the dynamics of Earth's lithosphere.

Key Vocabulary: lava, fissure, crater, extinct volcano, dormant volcano, pyroclastic flow, lahars, ash flow, lapilli, Aa lava, Pahoehoe lava, silica, effusive eruption, explosive eruption, pillow lava, Ring of Fire, tephra, viscosity, volcanic arc, composite volcano, cinder cone volcano, shield volcano, geyser, hot spots, etc.

Use the PowerPoint below to complete your Volcano Guided Notes.

Volcano Types

Volcano Observations Questions: Use the above illustrations of the three types of volcanoes and your notes to answer the questions below. When referencing the volcanoes, refer to the one on the left as Volcano A, the one in the middle as Volcano B, and the one on the right as Volcano C.

1. What type of volcano is Volcano A, Volcano B, and Volcano C?
2. What type of eruption did Volcano A, Volcano B, and Volcano C most likely have?
3. What type of lava most likely formed Volcano A, Volcano B, and Volcano C?
4. Why is Volcano A smaller than Volcano C?
5. Why does Volcano B have a wide base and low peak?
6. Why does Volcano C have snow on its top?
7. What can we deduce about the history of Volcano C?

Lava Types

Lava Observation Questions: Use the above illustrations of the three types of lava and your notes to answer the questions below. When referencing the lava, refer to the one on the left as Lava A, the one in the middle as Lava B, and the one on the right as Lava C.

1. What type of lava is Lava A, Lava B, and Lava C?
2. What type of eruption is associated with Lava A, Lava B, and Lava C?
3. What type of volcano is associated with Lava a, Lava B, and Lava C?
4. How is the composition of Lava different from Lava B?
5. What is unique about the formation of Lava C?
6. Which lava is associated with a volcano with high gas content? Why?
7. How would you describe the viscosity of each lava type?

The Rock Cycle

Introduction: The rock cycle refers to the diverse set of natural processes that lead to the formation and transformation of igneous, sedimentary, and metamorphic rocks. A short list of such processes includes weathering & erosion, deposition, burial, compaction, cementation, heat & pressure, melting, uplifting, cooling & crystallization, etc.

Learning Objectives: Upon completion of this section, you will be able to:

• differentiate between igneous, sedimentary, and metamorphic rocks using their key characteristics
• predict the type of rock that will form based on processes
• create a schematic sketch of the rock cycle from memory

Essential Question: How do rocks help us to better understand the dynamics of the lithosphere?

Key Vocabulary: magma, lava, weathering, erosion, deposition, burial, compaction, cementation, lithification, contact metamorphism, regional metamorphism, melting, crystallization, uplifting, clastic, conglomerate, fossils, sedimentary rock, metamorphic rock, igneous rock, intrusive, extrusive, foliated, nonfoliated, porphyritic, stratification, texture

Use the PowerPoint below to complete your Rock Cycle Guided Notes

The Rock Cycle Observation Questions: Use the above schematic sketch and your notes to answer the following questions.

1. How do rocks become igneous rock?
2. How do rocks become metamorphic rock?
3. How do rocks become sedimentary rock?
4. According to the schematic sketch, what process is missing with metamorphic rocks, igneous rocks, and sedimentary rocks?
5. All the processes of rock formation take place within the Earth's lithosphere with the exception of which rock type? Why?
6. How do all rocks that are formed within the lithosphere become sediments?
7. What are the two process by which continental rock can become oceanic sedimentary rock. What is the primary means by which this occurs?
8. How do plate tectonic processes play a role in the formation of rock? (Hint: How are oceanic plates formed and destroyed?)
9. What is the energy source above and below Earth's surface?
10. Write a general statement that summarizes the schematic sketch. Make sure your statement is true for all aspects of the schematic sketch.

We will complete the Rock Cycle Roulette in class.

Weathering, Erosion & Deposition

Introduction: Weathering and erosion are fundamental Earth processes that continually shape Earth's surface, and generate the sediments that circulate in the Rock Cycle. Weathering is the alteration and breakdown of rock minerals and rock masses when they are exposed to the atmosphere. Weathering changes rocks from a hard state, to become much softer and weaker, making them more easily eroded. Erosion is the removal (transport) of weathered rock materials down slope, and away, from their original site of weathering.

Learning Objectives: Upon completion of this section, you will be able to:

• differentiate between chemical and mechanical weathering
• identify the processes of mechanical and chemical weathering
• explain how karst topography is formed
• identify the climatic factors that influence mechanical and chemical weathering
• justify the erosion and deposition processes of meandering rivers
• explain differential weathering
• describe the four agents of erosion
• explain the factors that cause vertical and horizontal deposition
• differentiate between agents of sorted and unsorted deposition

Essential Question: How do the dynamics of weathering & erosion affect rocks, the formation of soil, and Earth's lithosphere?

Key Vocabulary: chemical weathering, mechanical weathering, frost wedging, thermal expansion, abrasion, salt crystal growth, exfoliation, oxidation, hydrolysis, carbonic acid, acid rain, surface area, dissolution, vertical or graded bedding, horizontal bedding, cross bedding, karst topography, sink hole, mass movement or wasting, meandering river

Complete the Erosion Notes using the PowerPoint below Slides 1-19

Soil Formation, Texture, & Conservation

Introduction: Soils are the loose mineral and organic materials found on earth's surface, usually (or averagely) made up of about 25% air, 25% water, 45% mineral and organic matter (humus, tiny living organisms, and sometimes plant residue). Soils may be formed in place from rock or formed in weathered rock and minerals that have been transported from where the original rock occurred. Soils are dynamic natural bodies having properties derived from the combined effect of climate and biotic activities, as modified by topography, acting on parent material over time.

Essential Question: How do the dynamics of soil formation help us to better understand rocks and the lithosphere?

Key Vocabulary: pedology, parent material, soil profile, horizons, O-Horizon, A-Horizon, B-Horizon, C-Horizon, leaching, texture, porosity, permeability, sand, silt, clay, humus, bedrock, fertility, topography

Complete the Soil Notes from Slides 20-40 of the PowerPoint below.

Watch this video before completing the Soil WS.