I. Earth s Layers a. Crust: Earth s outside layer. Made of mostly rock. i. Continental: er; made of mostly granite, forms the continents and shallow sea beds, floats! ii. Oceanic: er; dense rock such as basalt; lies in ocean basins b. Mantle: i. Upper Mantle: Layer under the crust. 1. : rock of the upper mantle 2. : rock under the lithosphere. Made of rock that is almost at its melting point but is not yet liquid. Has plasticity. ii. Lower Mantle: made of molten rock (magma) c. Core i. Outer Core 1. A layer; made of mostly iron and nickel 2. Constantly flowing creating a magnetic field that extends through planet Earth and even out into space! (Magnetosphere!) ii. Inner Core 1. The deepest layer of the Earth 2. Extremely hot 3. Also made of iron and nickel but is a layer because of the from all sides. II. Continental Drift a. Supercontinent - Pangaea i. Abraham Ortelius, a Dutch mapmaker in the late 1500 s suggested the continents were once a supercontinent that broke up over time. ii. Alfred Wegener, a German meteorologist, who presented the theory of in 1915. 1. Named the supercontinent iii. Estimated that over about 200 million years Pangaea broke up into two supercontinents that then drifted apart. 1. : Africa, South America, Australia, Antarctica, and the subcontinent of India 2. : North America, Europe, and northern Asia. b. Evidence: i. 1. Animals that would not have swam across an ocean but may have walked across a land bridge ii. 1. Appalachian Mountains iii.
III. 1. Evidence of glaciers in warm areas, tropical swamps in cold. iv. Uniformitarianism 1. the same geological process that happen on earth erosion, mountain building, etc happen in the ocean as well v. Sediment on the floor of the Atlantic Ocean is much thinner than would be expected possibly because land was once there - before the continents split and drifted apart. vi. Magnetic patterns in rocks on the ocean floor vii. Mid-Atlantic Ridge Mapping the Ocean Floor a. Two-thirds of Earth s surface is. b. Mapping the ocean floor is done with. i. Boat sends out ping a high-pitched sound ii. This sound wave hits the ocean floor and creates an echo iii. Echo of the ping bounces back to the boat and is caught by a microphone. iv. The time between releasing the ping and its echo returning are measured by a machine in order to figure out the distance it has traveled. v. As the ship travels it continues sending sound waves. vi. All the different measurements are combined to create a map of depths in the area the ship traveled over. These maps are called maps meaning they show depth below sea level. c. Features under the sea i. Beaches are the edges of the continental crust, also known as the Ocean in this area is shallow and it slopes downward into the sea. ii. Continental slope is much steeper than the shelf and continues to the ocean floor. 1. It is the boundary between the two types of earth s crust, the continental and oceanic. 2. The slope is not smooth. There are valleys, gullies and submarine canyons. iii. : made of sediment that eroded from the slope over time. iv. : a flat area at the bottom of the ocean. Is home to different landforms.
IV. 1. Seamount. 2. Guyots - seamounts that are. Their tops have eroded and are now flat. 3. Deep-sea trenches - narrow valleys in the sea floor. 4. Submarine Volcanoes: volcanoes that have formed on the ocean floor. If they stay active and grow fast enough, they will become volcanic islands! Plate Tectonics a. Earth is composed of many tectonic plates all are different sizes and shapes. b. Earthquakes occur on the ocean floor mostly at the boundaries of tectonic plates i. are instruments used to record data from earthquakes. This data shows scientists when and where earthquakes have occurred. c. Theory of plate tectonics explains that earth s continents move as part of plates in the lithosphere d. : Has the highest concentration of seismic activity in the world e. Three kinds of plate motion: i. Divergent plate boundaries: plates are moving and magma is surfacing. 1. Failed Rift: plates begin to split apart, but do not separate ii. Convergent plate boundaries: plates are moving. 1. Continental-continental plate collisions: the pieces of lithosphere get crumpled, folded, and thrust on top of one another a. form mountains 2. Oceanic-continental plate subduction: one moves up and on top of the other, causing the other to sink down into the asthenosphere a. form deep-sea trenches 3. Oceanic-Oceanic Collisions: One plate sinks slowly sliding beneath the other a. may create underwater volcanoes which eventually create islands iii. Transform plate boundaries: plates move alongside each other. 1. Form earthquakes
f. Two forces are the cause of plate motion: and g. Hot Spots: when volcanic activity occurs within a plate. Hot, molten material rises from the mantle, melting the crust above it to form volcanoes. V. Convection the transfer of heat by the or movement of the heated parts of a liquid or gas. a. Occurs because of differences in b. Heat from inner layers of the earth provides energy c. This heat causes rocks to melt and makes the mantle flow d. Very process i. 1. Occurs at mid-ocean ridges, which are elevated higher than the rest of the ocean floor. 2. Heat from rising magma pushes rocks upward from the ridge. As they cool, they become denser and gravity acts on these raised edges, pulling them downward and away from one another. This creates room for more hot magma to well up at the ridge, forming new crust. ii. 1. While gravity is pushing on one end of the thick plate, at the other end cooler, denser crust sinks into the mantle pulling on the rest of the plate. VI. Stress On Tectonic Plates a. : squeezing the rocks of the crust i. Formed at convergent plate boundaries b. : pulling the rocks and causing them to stretch or pull apart over a large area i. Formed at divergent plate boundaries c. : pushing the rock of the crust in two opposite directions alongside one another, resulting in a simple bend or break i. Formed at transform plate boundaries a b c d. Faults: a break in the rock along the fault line i. wall: rock that leans on the top of the fault line ii. Wall: rock block that is being leaned on iii. Normal: rocks are, spreading out iv. Reverse: rocks are, one over the other
v. : rocks bend or break sliding past each other VII. Earthquakes a. : where the earthquake starts. Energy waves travel out from this point in all directions. b. : the point on the surface that is directly above the focus. c. Seismograph: recordings of an earthquake i. P waves: pressure waves; primary waves 1. contract and release ii. S waves: seismic waves; secondary waves 1. move in a s motion