Earth Systems and Resources Earth Science Concepts APES

Earth Systems and Resources Earth Science Concepts APES Ms. Tooker 2015

Earth Science Concepts Geologic time scale Plate tectonics Earthquakes Volcanism Seasons Solar intensity Latitude/longitude

Geologic Time Scale Two time scales are used to measure the age of Earth. Sequence of layering of the rocks (strata) and evolution of life Radiometric time scale-natural radioactivity of chemical elements in rocks

Geologic Time Scale Organized into various units according to events that took place in each period Usually separated by major geologic or paleontological events (mass extinctions) Largest unit of time- eon Eon Eras Periods Epochs Stages

Geologic Time Scale

Key Principles of the Geologic Time Scale Rock layers (strata) are laid down in succession with each strata representing a “slice” of time. The principle of superposition- any given layer is probably older than those above it and younger than those below it.

Is the Geologic Time Scale perfect? ? NOOOO!!! Layers are often eroded, distorted, tilted, or uneven Layers laid down at the same time in different areas can have entirely different appearances A layer from any given area represents only part of Earth’s history

Earth Structure Formed 4. 6 billion years ago Third planet from the sun in the solar system Only planet known to support life

Earth Structure Biosphere- includes all forms of life (plants and animals) both on land in the sea Hydrosphere- includes all forms of water (fresh and saltwater, snow, ice) Lithosphere- includes the outermost shell of the planet (crust and upper mantle), approximately 62 miles thick

Crust Makes up 0. 5% of Earth’s total mass Floats on top of the mantle Oceanic crust From Earth’s surface to 7 miles down Relatively cold Rocky Brittle Fractures easily in earthquakes

Continental Crust Extends from Earth’s surface to 20 -30 miles down Appears stratified (layered) Composed of volcanic, sedimentary, and granite-type rocks Older areas may be metamorphic

Mantle Most of Earth’s mass Composed of iron, magnesium, aluminum, and silicon-oxygen compounds Over 1800˚F Mostly solid Upper third (asthenosphere) is more plastic-like

Plate Tectonics Continental drift theory- 1915, Alfred Wegener All present-day continents originally formed one landmass (Pangaea). Based on: Fossilized tropical plants discovered beneath Greenland’s icecaps Tropical regions on some continents has polar climates in the past, based on paleoclimatic data The continents fit together like pieces of a puzzle

Plate Tectonics Seafloor Spreading Theory- 1960 s Alternating patterns of magnetic properties were discovered in rocks found on the seafloor. Dating of the rocks indicated that as one moved away from the ridge, the rocks became older. New crust was being created at volcanic rift zones.

Plate Tectonics Earth’s plates float and move on the viscous asthenosphere Subduction zones- where two plates meet and move towards each other

Earth’s Major Plates

Transform Boundaries Occur where plates slide past each other. Friction and stress buildup from the sliding plates and earthquakes occur Example: San Andreas Fault (Pacific Plate and North American Plate)

Divergent Boundaries Occur where two plates slide apart from each other with the space that was created being filled with molten magma from below. Can create massive fault zones in the oceanic ridge system-frequent oceanic earthquakes Example- Mid-Atlantic Ridge and the East Pacific Rise

Convergent Boundaries Occur where two plates slide toward each other, forming a subduction zone (one plate moving under the other) or an orogonic belt (two plates collide and compress)

Oceanic-Continental Convergence Subduction zone- basaltic oceanic crust is more dense than granite continental crust. Examples- deep ocean trenches, stratovolcanoes and Volcanic Mts. on Land. ex. Cascade Mountains in the Pacific Northwest US

Oceanic-Oceanic Convergence An island arc (curved chain of volcanic islands rising from the deep seafloor and near a continent) Created by subduction processes Examples- Japan, Aleutian Islands in Alaska

Continental-Continental Convergence Mountain ranges are formed when plates collide Earth’s crust is compressed and pushed upward Examples- Himalayas

Earthquakes Two classes of seismic waves: body waves and surface waves Body waves travel through the interior of Earth Two types of body waves: P waves S waves

Earthquakes P waves: Travel through Earth Caused by expansion and contraction of bedrock

Earthquakes S waves: Produced when material moves either vertically or horizontally Travel only within the uppermost layers of Earth (along its surface)

Earthquakes Surface Waves: Produce rolling and/or swaying motion and are slower than P or S waves. Cause ground motion and damage.

Earthquakes The severity of an earthquake depends upon: The amount of potential energy that has been stored The distance the rock mass moved when the energy was released How far below the surface the movement occurred The makeup of the rock material

The Richter Scale

Tsunamis A series of waves created when a body of water is rapidly displaced, usually by an earthquake Generated when plate boundaries move abruptly move Subduction-zone-related earthquakes generate the majority of all tsunamis

Volcanoes Active volcanoes produce magma (melted rock) at the surface. About 95% of volcanoes occur at subduction zones and mid-oceanic ridges About 5% occur at hot spots Produce ejecta (lava rock and/or ash) Molten lava Toxic gases- steam, carbon dioxide, sulfur dioxide

Atmospheric Effects of Volcanoes

General Volcano Structure

Seasons, Solar Intensity, and Latitude Factors that affect the amount of solar energy at the surface of Earth: Earth’s rotation (once every 24 hours) Earth’s revolution around the sun (once per year) Atmospheric conditions

Summer Solstice Sun rises higher in the sky Stays above the horizon longer The sun’s rays strike the ground more directly (less of an angle)

Winter Solstice Northern hemisphere is titled away from the sun The sun rises lower in the sky Stays above the horizon for a shorter period of time

Earth is closest to the sun during the Northern Hemisphere winter (Dec. -Feb. ) Earth is farthest away during the Northern Hemisphere summer (June-Aug. ) Seasons are NOT caused by Earth’s distance from the sun!! Seasons are created by the angle of sunlight hitting the Earth.