The concept that describes and explains how the most significant features on the Earth's surface are produced by processes within the Earth when it acts units at the Earth's surface called plates. As a result, the plates to move around, and change in size and number over time.
Although there are other planets that are tectonically active, "plate tectonics" is unique to Earth within our solar system. The more general term "tectonics" refers to processes operating within any rocky planet to form their most significant surface features. Earth is the only planet in the solar system with tectonic activity dominated by structural units called plates.
The portions of the Earth's surface along plate boundaries are the most exposed to deformation due to collision and being pulled apart. Distinctive features associated with specific kinds of tectonic activity form at plate boundaries. Tectonic activity is fueled by sources of energy within the Earth's interior, and driven by the temperature difference between the interior and exterior.
The key processes of plate tectonics are seafloor spreading that takes place at midocean ridges, and subduction into trenches. Our current understanding of plate tectonic processes explains the existence and location of oceans, continents, large mountain ranges, volcanoes, earthquakes, and other large structures such as folds and faults.
Note: At the end of the unit, do the students have a clear concept of this difficult to define topic? It is often defined by example or by definitions that are slightly off the mark - as a force, scientific theory, mountain-building, structural feature of the Earth, concept, or other process. Just what is it?
Note: Do students have a sense of Earth's most "significant" features rather than just its largest features? Most of the significant features are large; however, small features can also be significant. Assigning significance takes judgment and knowledge, but that is a key transferable skill.
Pertaining to large-scale structural formation and deformation of the Earth's surface (or the surface of other planets). Large-scale structures that form as a result of deformation include folds, domes, basins and faults.
Note: Plate tectonics is a subset of the wider range of tectonics exhibited by other rocky planetary bodies.
Questions for Thought
- What is plate tectonics?
- What are the key landforms and structures at the Earth's surface that form as a result of tectonic activity? Landforms - "Any feature of Earth's surface having a distinct shape and origin. Landforms include major features (such as continents, ocean basins, plains, plateaus, and mountain ranges) and minor features (such as hills, valleys, slopes, drumlins, and dunes). Collectively, the landforms of Earth constitute the entire surface configuration of the planet." -
- How do we know that other planets in our solar system are tectonically active?
- Do any other planets have the same style of tectonic active as Earth, dominated by the presence of plates?
- Speculate on what the Earth's surface might look like once the Earth's interior cools and solidifies.
- Is continental drift a theory?
- Digital Atlas of Idaho - Glossary
Structures - Rock features, at many different scales, that form when rock is subjected to stress greater than the strength of rock (the rock's ability to resist deformation). Structures include folds, faults, domes, basins, monoclines, and joints.
- To compare several definitions of any word that interests you -
Type "define" and "the word" in a Google search, i.e. "define plate tectonics". Choose on "Web definitions for Plate Tectonics" to see several different definitions for comparison.
Other definitions - Plate tectonics Note Differences
- "Movements of the Earth's crustal plates, which result in changes in the position, size, and shape of continents and oceans."
- Galileo Journey to Jupiter, NASA
Note: Does plate tectonics involve motion of the "crust"?
- "... students should know about plate tectonics as a driving force that shapes Earth's surface."
- Usage of the term in Science Framework, Standard Set 3. Dynamic Earth Processes
Note: Is plate tectonics a "force"?
- "The theory that the Earth's lithosphere consists of large, rigid plates that move horizontally in response to the flow of the asthenosphere beneath them, and that interactions among the plates at their borders cause most major geologic activity, including the creation of oceans, continents, mountains, volcanoes, and earthquakes."
- Houghton Mifflin College Division Online Study Center
Note: Is the motion of the Earth's plates entirely horizontal?