Summary from Science Framework
Plate tectonics is a unifying geologic theory that explains the formation of major features of Earth’s surface and important geologic events. Although most scientists today consider Alfred Wegener to be the pioneer of the modern continental drift theory, he died with very little recognition for his accomplishment. Wegener asserted that evidence on Earth’s surface indicated that the continents were once attached as an entire land mass. He theorized that this land mass broke up into pieces that subsequently drifted apart. Today, geologists know that plate tectonic processes are responsible for most of the major features of Earth’s crust (including continental configuration, mountains, island arcs, and ocean floor topography) and are an important contributor to the recycling of material in the rock cycle. Driven by the flow of heat and material within Earth, these processes cause stresses in Earth’s crust that are released through earthquakes and volcanic activity. Mountain building counters the constant destructive effects of weathering and erosion that eventually wear down Earth’s surface features.
excerpt from:
Chapter Five: Earth Science, Investigation and Experimentation.
Science Framework for California Public Schools: Kindergarten Through Grade Twelve, 2004.
California Department of Education.
Acquired from online source on July 13, 2007.
Knowledge and capabilities related to plate tectonics can help save lives, property and wealth when it is considered in making many kinds of personal, community and business decisions. Plate tectonic processes control where, when, how intensely and how often geologic hazards such as earthquakes, volcanoes and tsunami strike.
Knowledge and capabilites related to the Earth's tectonic history helps to locate and/or extract natural resources, such as petroleum, soils, groundwater and other minerals, of economic value.
Knowledge of tectonic settings allows us to define and understand differences in the global distribution of particular natural resources, such as soil types, water supply, fossil fuels and minerals.
Knowledge of tectonic change over very long periods of time helps us to understand the succession of living things revealed by fossils, and the interpendence of life and ephemeral environments over many scales of space and time.
Knowledge of tectonic processes and its causes allows us to understand our own planet in the developing context of understanding all rocky planets, in our own solar system and beyond.
The familiar arrangement of land, ocean and mountain ranges is temporary and unique to our time. Not long ago, in a geologist's way of thinking, India was next to Antarctica and the Atlantic Ocean didn't even exist. It's because the Earth continually reshapes its surface by the processes of plate tectonics. The subject of plate tectonics, covers the processes the shape the Earth's surface, the mechanisms that drive these processes, the resulting surface features and the reconstruction of past global geographies.
The overarching concept of plate tectonics explains the presence and pattern of Earth's most significant surface features - its oceans, land and mountains - today and in the past. By learning about plate tectonics, individuals are able to look at mountains or the ocean and know why it is there. The historical development of this revolutionary concept illustrates how human understanding of the natural world progresses over time.
The term "tectonics" refers to planetary processes that shape and deform planets, particularly large-scale surface features such as volcanoes, mountains that are not volcanic in origin, faults and folds. Since tectonic processes on Earth are characterized by the motion and resizing of eggshell-like units called "plates", at its surface, this style of tectonics is called plate tectonics. Other rocky planets in our solar system may be (or have been) tectonically active, but none seem to exhibit evidence of plate tectonics
The motion of tectonic plates and the slow convective motion of rock inside the Earth are driven by the same sources of energy within the Earth. These sources of energy include heat trapped inside the Earth long ago and energy released by ongoing radioactive decay. But plate motion doesn't seem to be related to convective motion in a simple way. The plates are not dragged along the Earth's surface by the convective motion of underlying rock. The complex relationship between convection and plate motion is not well understood.
The key processes of plate tectonics on Earth, seafloor spreading and subduction, take place where rock moves upward and downward, respectively. These processes are associated with the major features of the seafloor: Sea floor spreading forms and takes place under midocean ridges and subduction occurs at trenches. Is it the change in the size and shape of the oceans by these two processes that results in the repositioning of continents over time. This concept of plate tectonics differs from continental drift in a major way - it does not require continents to plow through oceanic crust like swimming ducks through water.
Sometime long into the future, the Earth's interior will become too cool to support tectonic activity. Until that happens, tectonic processses will work against the wearing effects of erosion and continue to reshape the surface of the planet, maintaining the most distinctive features of the Earth such as its highest mountain ranges and deepest canyons.
Note: Everything here is preliminary.
Please feel free to use it, but consider it a draft. :)
© 2007 Earthguide at Scripps Institution of Oceanography.
All rights reserved.
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