EARTH SCIENCE FILM NOTES:
*Inner Core: Innermost layer of Earth, densest, hottest, mostly Fe.
*Outer Core: Mostly Fe, surrounds inner core, liquid.
*Lower Mantle: Thickest layer, ultra heavy rock.
*Upper Mantle: Part of lithosphere, brittle.
*Crust: You live on it, relatively paper thin, brittle, least dense, floats on mantle.
*Lithosphere: Solid part of Earth.
*Asthenosphere: Layer of deformable rock below the lithosphere.
*Convection: Transfer of heat within a liquid or gas.
*Conduction: Transfer of heat through matter by direct contact.
*Thermal Radiation: Transfer of heat through space at speed of light
*Density: The amount of matter in a given volume.
*Plate Tectonics: The theory that the Earth’s crust is broken into plates that float on the upper mantle.
*Divergent Zone: where two plates pull apart. Mid-ocean ridge seafloor spreading.
*Convergent Zone: where two plates come together (forms mountains/uplifting)
*Oceanic Crust: Dense crust formed by seafloor spreading at Mid-Ocean Ridges.
*Continental Crust: Less-dense crust that makes up the continents.
*Continental Drift: A theory stating that the Earth's continents have been joined together and have moved away from each other at different times in the Earth's history.
*Pangaea: Single, giant landmass, or continent, that later broke apart.
*Seafloor Spreading: Process that forms new seafloor.
*Subduction: Place where heavier oceanic crust is forced below lighter continental crust.
*Mid-Ocean Ridge: An ocean floor feature resembling a mountain ridge on land. Divergent zone.
*Trench: Deep canyon on the ocean floor formed by subduction.
*Hot Spot: A volcanic area that forms as a tectonic plate moves over a point heated from deep within the Earth's mantle.
Earth is Continuously Changing
- Earth’s geosphere changes through geological, hydrological, physical, chemical, and biological processes that are explained by universal laws. These changes can be small or large, continuous or sporadic, and gradual or catastrophic.
- Earth like other planets is still cooling, though radioactive decay continuously generates internal heat. This heat flows in and out of Earth’s interior largely through convection but also through conduction and radiation. The flow of Earth’s heat is like its life blood driving its internal motion. Earth’s interior is in constant motion through the process of convection, with important consequences for the surface.
- Convection in the iron-rich liquid outer core along with Earth's rotation around its axis generates Earth's magnetic field. By deflecting solar winds around the planet, the magnetic field prevents the solar wind from stripping away earth’s atmosphere.
- Convections in the solid mantle drive the many processes of plate tectonics, including the movement of the continents and oceanic crust. Earth’s tectonic plates consist of the rocky crust and uppermost mantle, and move slowly with respect to one another. new oceanic plate forms constantly at mid-ocean ridges and other spreading centers, sinking back into the mantle at ocean trenches. Tectonic plates move apart at rates up to 10 centimeters per year. Many active geologic processes occur at plate boundaries.
- Plate tectonics changes the faces, shapes, sizes, and the locations of continents, ocean basins, and mountain ranges, the patterns of ocean circulation and climate, the location of earthquakes and volcanoes, and the distribution of resources and living organism.
- Earth materials take many different forms as they cycle through the geosphere. Rocks form from the cooling of magma, the accumulation and consolidation of sediments and the alteration of older rocks by heat, pressure and fluid. These three processes form sedimentary, igneous and metamorphic rocks.
- Landscape result from the dynamic interplay between processes that form and uplift new crust and processes that destroy and depress the crust. This interplay is affected by gravity, density differences, plate tectonics, climate, water, the actions of living organisms, and the resistance of earth material to the rate in which rocks weather and erode. Weathered and unstable rock materials erode from some parts of Earth’s surface and are deposited in others. Under the influence of gravity, rocks fall down hill. Water, ice and air carry erode sediments to lower elevations and ultimately to the oceans. Shorelines move back-and-forth across continents, depositing sediments that become the surface rocks of the land. Through dynamic processes of plate tectonics and glaciation earth sea level rises and falls by up to hundreds of meters. This fluctuation causes shorelines to advance and recede by hundreds of kilometers. The upper rock layers of most continents form when rising sea-levels flooded the interior of the continents. And that's a big idea: Earth is continuously changing.
Earth is 4.6 Billion Years Old:
- Earth’s rocks provide a record of its history.
- Earth scientists use the structure, sequence and properties of rocks, sediments and fossils. To reconstruct events in Earth history, understanding the geologic processes that are active today is crucial in interpreting Earth’s past. Decay rates of radioactive elements are the primary means of obtaining numerical ages of rocks and organic remains.
- Our solar system formed from a vast cloud of gas and dust 4.6 billion years ago. This age of year is well-established from the decay rates of radioactive elements found in meteorites and rocks from the moon. Some of this gas and dust was the remains of the supernova explosion of a previous star. In this sense we could say that our bodies are made of stardust.
- Earth formed from dust gas and multiple collisions of smaller planetary bodies. It was the accumulation of dust, gas and small planetary bodies that formed the beginning of earth. Rocks surrounded the core was mostly molten early in earth’s history. Driven by gravity first metallic core formed as iron sank to the center.
- The earth slowly cooled to form Earth’s mantle and crust. The atoms of different elements combine to make minerals which combined to make more rocks. Earth’s ocean and atmosphere began to form more than 4 billion years ago from the rise of lighter materials out of the mantle. Earth's crust has two distinct types continental and oceanic. Continental crust exists at Earth’s surface and can be billions of years old. oceanic crust continuously forms and recycled back into the mantle. In the ocean crust is nowhere older than about 200 million years.
- Studying other objects in the solar system helps us learn the earth's history. Many aspects of Earth's early history revealed by objects in the solar system that is not changed as much as Earth’s. Active geologic processes such as plate tectonics and erosion have destroyed or altered most of Earth’s early rock record.
- Life on earth began more than 3.5 billion years ago. Fossils indicate that life began with single celled organisms which were the only life forms for billions of years. Humans or Homo sapiens have existed for only a very small fraction of about 0.004% of Earth's history.
- Over Earth’s vast history both gradual and catastrophic processes have produced enormous changes. Supercontinents formed and broke apart. The compositions of the atmosphere and ocean changed. Sea level rose and fell. Living species evolve and went extinct. Ice sheets advanced and melted away. Meteorites slammed into the earth. Mountains formed and eroded away. And that's a big idea: Earth is 4.6 billion years old.