SmartStarter What are the layers of the earth? Does your description depend on the chemical or physical (or both) make up?

Geological Oceanography Universe/Solar System/Earth Formation Layers 2 ways: Physical & Chemical Continental Drift Seafloor Spreading Geologic Features Depth data – History Unifying Theory: Plate Tectonics

Formation of the Universe: Nebular Hypothesis Proto-Star & Proto-Planets

1800 miles 1411 miles 1491 miles Fe Chemical: 3 layers

If it is cooling, where does the heat come from? Why is it molten? Earth's Heat

Continental Drift

What is the difference between igneous rock and metamorphic rock? 9/16&17/2015 SMARTStarter What is the difference between igneous rock and metamorphic rock? Bonus… How hot do you think the inner core is? Igneous is from lava melting. Less dense. Metamorphic is from sedimentary/igneous + pressure/heat – metamorphism – physical/chemical change Core = 5k Celsius or 9032 F…..same as the sun. Inner core is mostly Fe same as outer but with more pressure it is a solid (2008 Seismic data) Inner core – 1491 miles / 2400 km Outer core – 2270km / 1411 miles mantle

Igneous Rock Cooled magma Primary formation is recycling machine Magma vs. lava…? Primary formation is recycling machine

Igneous Rock Specific gravity is the ratio of the density of a substance to the density (mass of the same unit volume) of a reference substance. Gram/cubic centimeter = gm/cc = Density (SI units) = SG X Density of water  (1.0 g/cc or 1000 kg/cubic metre) Density (in lb/cu ft.) = SG X 62.4

Processes: Weathering Erosion Chemical breakdown Sediment Leaching movement

Sedimentary Rock LAYERS Fossils Petroleum Coal = fossil fuels

Metamorphic Rock Heat and Pressure – chemical change

What is the difference between the crust and the lithosphere?

Why is the crust different? Lithosphere vs. Crust Crust plus upper mantle Why is the crust different? Dynamic changes Different rocks…three types Pressure/heat make the chemical/physical characteristics different

Rock Cycle describes why and how “rock” is different

The Rock Cycle Law of Conservation of Mass The Law of Conservation of Mass states that matter can be changed from one form into another, mixtures can be separated or made, and pure substances can be decomposed, but the total amount of mass remains constant. We can state this important law in another way. The total mass of the universe is constant within measurable limits; whenever matter undergoes a change, the total mass of the products of the change is, within measurable limits, the same as the total mass of the reactants.  Law of Conservation of Mass

SmartStart 9/18 - Friday What processes change rocks from: 1. magma/lava to igneous rock 2. Igneous to sedimentary 3. Sedimentary to metamorphic 4. Metamorphic to Igneous

Announcements Return tests Good things Retake – requirement & responsibility Good things

MONDAY SmartStarter…. What is the name of the ocean that surrounded pangaea? Bonus: What is the name of the person who proposed the theory of continental drift?

Continental Drift Watch this…

Continental Drift According to Wegener’s hypothesis, the continents move slowly across Earth’s surface in a process called continental drift.

Continental Drift: “Show me the DATA!” Shapes of the continents, mapmakers noticed how well the shapes of North and South America fit together with Europe and Africa. fossils of species of land-based plants and animals were discovered on continents separated by large oceans. Glossopteris

Wegener called the ancient supercontinent Pangaea. Continental Drift 1912: Alfred Wegener proposed a hypothesis of continental drift to explain these puzzling observations. Wegener called the ancient supercontinent Pangaea. Remember what else happened in 1912?

The continents move slowly across Earth's surface over time. Continental Drift The continents move slowly across Earth's surface over time. Panthalassa

Continental Drift – The Missing pieces Wegener was unable to explain how the continents could plow through the solid rock of the sea floor or what force could move entire continents. As a result, most geologists rejected continental drift.

Sea-floor Spreading Several decades after Wegener proposed his hypothesis, new evidence led geologists to reconsider his ideas. New evidence helped scientists propose the theory of plate tectonics.

Sea-floor Spreading: Bathymetric Data The Mid-Ocean Ridge When scientists mapped the ocean floor, they found a chain of underwater mountains which they called the mid-ocean ridge. It forms the world’s longest mountain chain.

Sea-floor Spreading

Sea-floor Spreading Sea-floor spreading: process by which new oceanic crust is created at mid-ocean ridges as older crust moves away. As sea-floor spreading occurs, old oceanic plates sink into the mantle in the process of subduction.

Formation of Oceanic Crust Sea-floor Spreading Formation of Oceanic Crust Sea-floor spreading is the process by which new oceanic crust is created at mid-ocean ridges as older crust moves away. The mid-ocean ridge is a huge crack where magma pushes upward. The parts of the ocean floor on both sides of the central valley are moving apart. Magma from the mantle wells up and solidifies to form new oceanic crust.

Sea-floor Spreading During sea-floor spreading, oceanic crust forms at the mid-ocean ridge. This crust gradually moves toward a subduction zone, where old crust sinks beneath a trench. Oceanic lithosphere Oceanic crust Mid-ocean ridge Trench Volcano Continental crust Continental lithosphere Asthenosphere Sediment Magma

Sea-floor Spreading Subduction of Oceanic Plates As sea-floor spreading occurs, old oceanic plates sink into the mantle in the process of subduction. Subduction zones are near the edges of oceanic plates. As a plate sinks through a subduction zone, it bends, forming a depression in the ocean floor called a trench.

Sea-floor Spreading Subduction occurs because, as an oceanic plate moves away from the mid-ocean ridge, it gradually cools and becomes more dense. During subduction, the force of gravity slowly pulls the dense edges of oceanic plates into the mantle, destroying old ocean floor. Sea-floor spreading and subduction together act like a giant conveyor belt.

Evidence for Sea-floor Spreading Scientists discovered patterns of parallel magnetic “stripes” that were identical on the two sides of the mid-ocean ridge. Earth’s magnetic field has reversed itself many times. The magnetic field causes rock crystals to line up in a certain way before the rock solidifies. Stripes show that new ocean floor was added to both sides of the mid-ocean ridge.

Sea-floor Spreading The pattern of magnetic stripes in the rock of the ocean floor is the same on both sides of the mid-ocean ridge. Normal polarity Reversed polarity Mid-ocean ridge Oceanic crust Magma Mantle

Sea-floor Spreading Geologists used radioactive dating to determine the ages of rock samples from the ocean floor. They found that rocks nearer the mid-ocean ridge were younger, and rocks farther from the ridge were older.

Paleomagnetism Directions of magnetism…changes Result…magnetic stripping of the sea floor

Oceanic vs. Continental Plates …Basalt vs. Granite

Basalt Basalt is predominantly composed of crystals of grayish plagioclase feldspar, blackish pyroxene, and greenish olivine minerals and largely forms from magma extruded along divergent plate boundaries. Low silica content. (basic). Dark, dense. = olivene + pyroxene + Ca-Feldspar in solid solution. Basaltic rocks (gabbro & basalt) are made up of feldspars and other minerals common in planetary crusts. They have been identified as major surface rocks on the dark lunar planes and much of Mars, Venus and the asteroid Vesta.

Granite Granite is predominantly composed of whitish to pinkish plagioclase and potassium feldspars and clear to whitish quartz minerals (along with minor amounts of biotite, muscovite, and horneblende minerals Granite. (Continental crust) Density 2.7-2.8. High silica content (acidic). = quartz + mica + K-feldspar in solid solution. 60% orthoclase and plagioclase fledspars + 25% quartz + 5% darker minerals (biotite, hornblende). Color from flesh to black. Crystals intermingled. Hard, rigid, tough. Granitic rock is much less common on the other terrestrial planets, a fact having to do with the fractionation (where early crystallizing minerals separate fromt he rest of a magma), a process that takes place uniquely on earth, due to the prevalence of plate tectonics.

Density Differences… Basalt. (Ocean crust) Density 2.9. Granite. (Continental crust) Density 2.7-2.8.

Isostatic Equilibrium Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces… buoyancy Large regions of Earth's continents are held above sea level by isostatic equilibrium, a process analogous to a ship floating in water. Isostatic Equilibrium. Huge plates of crustal and upper mantle material (lithosphere) “float” on more dense, plastically flowing rocks of the asthenosphere. The “depth” to which a plate, or block of crust, sinks is a function of its weight and varies as the weight changes

Isostasy Isostatic adjustment - Isostatic Rebound – glaciers tie into the story too! Adjustment is when there is a change in the mass and the level of the plate floating on the mantle’s plastic magma lowers…like adding containers to a contain ship or filling an oil tanker in Valdez.

SmartStarter The summit of Mount Everest is the highest point on Earth – 8848 m – 29,029’ Challenger Deep is the lowest point in the ocean at -10,916 m or 35,994’ What do you think the average height (above sea-level) of continents is? 2. Average depth of the ocean? The Challenger Deep is the deepest known point in the Earth's seabed hydrosphere, with a depth of 10,898 to 10,916 m by direct measurement from submersibles, and slightly more by sonar bathymetry. Elevation: -35,994‘ Mount Everest, also known in Nepal as Sagarmāthā and in Tibet as Chomolungma, is Earth's highest mountain. It is located in the Mahalangur section of the Himalayas. Its peak is 8,848 metres (29,029 ft) above sea level.[1] It is not the furthest summit from the centre of the Earth. That honour goes to Mount Chimborazo, in the Andes.[8] …because the earth is not a sphere

On average the continents are 840 m above sea level while the average depth of the ocean basins is 3730 m. If the earth were a smooth sphere with the land planed off to fill the ocean basins the earth would be uniformly covered by water to a depth of 2430 m.

Africa The Red Sea between Africa and the Arabian peninsula in Asia marks a region where two pieces of the lithosphere are slowly moving apart. Over the next 100 million years, the Red Sea could become an ocean. Red Sea

Continental Drift What are plate tectonics and continental drift? The theory of plate tectonics explains the formation and movement of Earth’s plates. Wegener hypothesized that the continents were once joined in a single supercontinent, which then broke into pieces that moved apart.

Continental Drift Plate tectonics is the theory that pieces of Earth’s lithosphere, called plates, move about slowly on top of the asthenosphere. According to Wegener’s hypothesis, the continents move slowly across Earth’s surface in a process called continental drift.

Continental Drift When the early explorers began to discover the shapes of the continents, mapmakers noticed how well the shapes of North and South America fit together with Europe and Africa. Later on, geologists discovered fossils of species of land-based plants and animals on continents separated by large oceans.

Continental Drift Fossils of Glossopteris and other plants and animals on widely separated land masses led Alfred Wegener to hypothesize that the continents had once been joined.

Wegener called the ancient supercontinent Pangaea. Continental Drift In 1912, Alfred Wegener proposed a hypothesis of continental drift to explain these puzzling observations. Wegener called the ancient supercontinent Pangaea. Panthalassa.

Continental Drift Continental drift explains why the continents seem to fit together. It also explains why the fossils from a single region appear across the globe. Wegener was unable to explain how the continents could plow through the solid rock of the sea floor or what force could move entire continents. As a result, most geologists rejected continental drift.

Continental Drift The continents move slowly across Earth's surface over time.

Sea-floor Spreading What are the roles of sea-floor spreading and subduction in plate tectonics? Sea-floor spreading creates new oceanic crust at mid-ocean ridges. Subduction destroys old oceanic crust at subduction zones. Where is the newest oceanic lithosphere? Oldest?

Sea-floor Spreading Sea-floor spreading is the process by which new oceanic crust is created at mid-ocean ridges as older crust moves away. As sea-floor spreading occurs, old oceanic plates sink into the mantle in the process of subduction.

Sea-floor Spreading Several decades after Wegener proposed his hypothesis, new evidence led geologists to reconsider his ideas. New evidence helped scientists propose the theory of plate tectonics.

Sea-floor Spreading The Mid-Ocean Ridge When scientists mapped the ocean floor, they found a chain of underwater mountains which they called the mid-ocean ridge. It forms the world’s longest mountain chain.

Sea-floor Spreading This false-color satellite image shows a segment of the mid-ocean ridge in the Atlantic Ocean. The ridge system winds through all of Earth’s oceans.

Formation of Oceanic Crust Sea-floor Spreading Formation of Oceanic Crust Sea-floor spreading is the process by which new oceanic crust is created at mid-ocean ridges as older crust moves away. The mid-ocean ridge is a huge crack where magma pushes upward. The parts of the ocean floor on both sides of the central valley are moving apart. Magma from the mantle wells up and solidifies to form new oceanic crust.

Sea-floor Spreading During sea-floor spreading, oceanic crust forms at the mid-ocean ridge. This crust gradually moves toward a subduction zone, where old crust sinks beneath a trench. Oceanic lithosphere Oceanic crust Mid-ocean ridge Trench Volcano Continental crust Continental lithosphere Asthenosphere Sediment Magma

Sea-floor Spreading Subduction of Oceanic Plates As sea-floor spreading occurs, old oceanic plates sink into the mantle in the process of subduction. Subduction zones are near the edges of oceanic plates. As a plate sinks through a subduction zone, it bends, forming a depression in the ocean floor called a trench.

Sea-floor Spreading Subduction occurs because, as an oceanic plate moves away from the mid-ocean ridge, it gradually cools and becomes more dense. During subduction, the force of gravity slowly pulls the dense edges of oceanic plates into the mantle, destroying old ocean floor. Sea-floor spreading and subduction together act like a giant conveyor belt.

Evidence for Sea-floor Spreading Scientists discovered patterns of parallel magnetic “stripes” that were identical on the two sides of the mid-ocean ridge. Earth’s magnetic field has reversed itself many times. The magnetic field causes rock crystals to line up in a certain way before the rock solidifies. Stripes show that new ocean floor was added to both sides of the mid-ocean ridge.

Sea-floor Spreading The pattern of magnetic stripes in the rock of the ocean floor is the same on both sides of the mid-ocean ridge. Normal polarity Reversed polarity Mid-ocean ridge Oceanic crust Magma Mantle

Sea-floor Spreading Geologists used radioactive dating to determine the ages of rock samples from the ocean floor. They found that rocks nearer the mid-ocean ridge were younger, and rocks farther from the ridge were older.

The Theory of Plate Tectonics Why do tectonic plates move? Plate motions are the visible part of the process of mantle convection.

The Theory of Plate Tectonics Convection currents form in the mantle as hot rock rises, cools and spreads out, and then sinks back into the mantle at subduction zones. These sinking slabs of dense lithosphere and heat from within Earth drive the circulation of convection currents in the mantle.

The Theory of Plate Tectonics Lithosphere Convection currents Outer core Inner core Mantle Heat flows from Earth’s hot interior toward the cooler surface mainly through large convection currents in the mantle. Plates are the uppermost part of a global convection system.

The Theory of Plate Tectonics The heat that drives convection in the mantle comes from two sources. Earth was very hot when it first formed, and some of the heat moving upward in convection currents is due to the gradual cooling of its interior. A second source of heat is the result of the decay of radioactive isotopes that are distributed throughout the mantle and crust.

Plate Boundaries What are the types of plate boundaries and what are their characteristics? There are three types of plate boundaries: divergent boundaries, convergent boundaries, and transform boundaries.

Plate Boundaries There are about a dozen major tectonic plates. Most major plates contain both continental and oceanic crust. The edges of plates meet at plate boundaries. As the plates move apart, collide, or slide past each other, they cause changes in Earth’s surface.

Plate Boundaries The lithosphere is broken into about a dozen large plates, which move slowly over Earth’s surface.

The plates move very slowly, about 0.1 to 10 centimeters per year. Plate Boundaries The plates move very slowly, about 0.1 to 10 centimeters per year. Plates move away from each other along a divergent boundary. The mid-ocean ridge forms a divergent boundary. Divergent boundaries can also be found on land, for instance, in Africa. When plates move apart, magma rises to fill the gap and form new rock at the edge of each plate.

Plate Boundaries Plates come together, or collide, at a convergent boundary. The most common convergent boundary is one where an oceanic plate is subducted beneath a trench. At a transform boundary, plates slide past each other, moving in opposite directions. Rock is neither created nor destroyed at a transform boundary.

Check this out… Plate Boundaries Plates meet at three types of boundaries: divergent boundaries, convergent boundaries, and transform boundaries. Divergent Boundary Convergent Boundary Transform Boundary Lithosphere Asthenosphere

Mountain Building Where do most mountains form? Geologists found that most mountains form along plate boundaries.

Mountain Building Some mountains form when two plates with continental crust at their edges collide along a convergent boundary. Neither plate is subducted during such collisions. The crust buckles, folds, and thickens, pushing up tall mountains.

Mountains can also form along diverging plate boundaries. Mountain Building Mountains can also form along diverging plate boundaries. The mid-ocean ridge system forms one long chain of mountains on the ocean floor. In places, the mountains of the mid-ocean ridge rise above sea level. One example is the island of Iceland in the North Atlantic Ocean.

Mountain Building The Andes, which extend along the western side of the South American plate, have risen as a result of a collision between that plate and the Nazca Plate

Assessment Questions According to Wegener’s hypothesis of continental drift, what is Pangaea? Africa and South America before they drifted apart a tectonic plate located in the Pacific Ocean the process by which continents move an ancient supercontinent formed 260 million years ago

Assessment Questions According to Wegener’s hypothesis of continental drift, what is Pangaea? Africa and South America before they drifted apart a tectonic plate located in the Pacific Ocean the process by which continents move an ancient supercontinent formed 260 million years ago ANS: D

Assessment Questions What type of plate boundary causes mountain chains, such as the Himalayas, to form? divergent convection convergent transform

Assessment Questions What type of plate boundary causes mountain chains, such as the Himalayas, to form? divergent convection convergent transform ANS: C

What causes Earth’s plates to move? Assessment Questions What causes Earth’s plates to move? gravitational force between continents magnetic forces in the lithosphere global winds pushing continents convection currents in Earth’s mantle

What causes Earth’s plates to move? Assessment Questions What causes Earth’s plates to move? gravitational force between continents magnetic forces in the lithosphere global winds pushing continents convection currents in Earth’s mantle ANS: D