Notes: ROCK CYCLE & SOIL

NOTES: ROCK CYCLE & SOIL

NOTES: PLATE TECTONICS

PLATE TECTONICS: The theory that the earth’s crust is divided into plates that move over top of the earth’s mantle.

I. CONTINENTAL DRIFT: ALFRED WEGNER - 1920’s - Did NOT explain plate motion a . Continental Puzzle: The earth’s continents look as if they fit together like a puzzle (ex. Africa & S. America) b. Similar Fossils: there are fossils that have been found on different continents during the same geologic time frame. (Ex. A fossil that was found on both the eastern part of the US & western Europe, but nowhere else in the world. The organism could not have traveled from one area to the other). c. Ancient Climates: It was determined that there were similar climates around the same geologic time frame on two different continents that looks like they could have fit in the same puzzle. (Ex: Coal in Antartica) d. Similar rock types & structures: Some mountain ranges look as if they would have been a part of the same range before the continents separated. (EX: Appalachian Mts correlate with Mt’s in Africa and Europe)

II. PLATE TECTONICS: MANY SCIENTISTS - 1960’s - EXPLAINED PLATE MOTION a. Earthquake patterns: earthquakes tend to occur in areas along plate boundaries (Ex: The Ring of Fire) b. Paleomagnetism: when two plates separate from each other, especially along the ocean floor, magma is released. This iron-rich magma magnetizes towards the north & south pole. As the plates move & spread apart, newer magma is formed, again pointing to the poles, however, since the other older magma has moved (and still points in it’s original direction) the magnetic rock points in different directions. (Example above) c. Hot Spots: places in the mantle close to the crust that are hotter than other regions of the mantle. The heat & pressure cause the magma to be released, resulting in volcanoes. (Ex. How the Hawaiian Islands were formed) III. Plate Boundaries & Movement a. CONVERGENT PLATE BOUNDARIES: when two plates move into one another i. Two continental plates collide: a. results in mountains ii. Two oceanic plates collide: one moves under the other resulting in: a. trench forming b. land or island volcano Convergent Oceanic- Convergent Oceanic- Convergent Continental- Oceanic Continental Continental

Example on Earth: Example on Earth: Example on Earth: HIMALAYAS JAPAN, PHILIPPINES, CASCADE MOUNTAINS, ALEUTIAN ISLANDS ANDES MOUNTAINS b. DIVERGENT PLATE BOUNDARIES: c. TRANSFORM FAULT when two plates move away from one another BOUNDARIES: when two i. Two plates move apart: magma comes up & spreads plates move parallel to one resulting in ridges (i.e. the Mid-Atlantic Ridge) another. Creates cracks in the crust. Divergent Oceanic Plates Divergent Continental Plates Transform Boundary

Example on Earth: Example on Earth: Example on Earth: MID-ATLANTIC RIDGE GREAT RIFT VALLEY SAN ANDREAS FAULT (Africa) NOTES: EARTHQUAKES

Earthquakes: The shaking of the earth due to the rapid release of built up energy in the earth’s crust.

I. Causes of Earthquakes: The Elastic Rebound Theory a. Slight movement of rocks in/on the earth’s crust b. Energy builds up over time as the rocks are bent c. Rocks are bent to their breaking point, releasing energy in the form of vibrations (earthquake) d. Rocks return to their original shape

II. Types of Earthquake Waves: a. Body Waves: travel through the earth’s interior i. P-Waves (Primary waves): compression waves 1. travel fastest 2. moves through solid, liquid or gas ii. S-Waves (Secondary waves): 1. move up and down 2. moves through solid only b. Surface Waves: travel more slowly than body waves. Travel just below the earth’s surface i. Rayleigh waves (ground roll): travel like ripples in the water. ii. Love waves: cause ground shearing

III. Location of an Earthquake: a. Occurs beneath the earth’s surface (focus) b. The epicenter is the area on the map where we say that the earthquake occurs (directly above the focus) i. Seismographs are placed in many places around the globe – these are instruments that measure seismic activity (specifically, waves) ii. Triangulation: Draw circles around 3 different seismic centers based on the intensity of the earthquake. Where the 3 circles meet is the epicenter of the earthquake. c. Reading a seismogram (the readout from the seismograph):

IV. Damage from Earthquakes: a. Infrastructure damaged (buildings) b. Liquefaction: water saturates soil, causing it to move under buildings c. Tsunamis (massive waves): biggest on record was the one on Dec. 26, 2006 d. Subsidence (ground sinks) causing landslides e. Fires due to broken gas lines under cities

NOTES: VOLCANOES

Volcano: an opening or rupture in the earth’s crust that allows molten rock, ash & gas to be released from beneath the earth’s surface. TYPES OF VOLCANOES

Drawing

Type STRATOVOLCANO CINDER VOLCANO SHIELD VOLCANO

ISLAND BUILDING Tallest volcanoes Smallest volcanoes volcanoes Description Forcefull eruptions Non violent eruptions Lava flows slow over Pyroclastic flow & lava lava many years. Mt St. Helens (USA) Paricutin (Mexico) Kilauea & Mona Loa Example Mt Vesuvius (Italy) Stromboli (Italy) (Hawaii)