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Main Curriculum Tie:
Alternatives if the Landform kit is not available in your area: The
Dynamic Planet map can be viewed and ordered from the website:
http://store.usgs.gov" Any US relief map with the mountain regions highlighted
can be used. Fault blocks can be purchased from multiple sources and there are
multiple sites on the Internet to even make your own fault blocks.
Background For Teachers:
A divergent plate boundary occurs when two plates move away from each other. The magma under the earth oozes up between the plates and hardens to become new crust. Many volcanoes are found along plates that are spreading apart. Most of this crust formation occurs under the ocean along the Mid Atlantic Ridge. There are few earthquakes along plates that are spreading apart. Volcanoes in Iceland are formed from the North American and Eurasian Plate spreading apart.
A convergent plate boundary occurs when two plates push against each other. When the plates collide the less dense plate overrides the denser plate, this is called subduction. The crust on the plate that is pushed under is subjected to the high temperatures of the mantle below and the crust melts. As the old crust melts, volcanoes form. Plate edges are rough and two edges can get stuck together while the rest of the plate keeps moving. Finally, when the plate has moved far enough, the edges unstick and an earthquake occurs. 3/4 of all earthquakes occur at convergent boundaries. Many mountain ranges occur along these lines because when one plate doesn’t completely move under the other, the earth crumbles and this uplifts the crust into mountains. In Europe, the Alps are formed from the African and Eurasian plate bumping into each other.
A transform plate boundary occurs when two plates slide past each other. Where the crust is rough, the two plates build up tension as they slide. When one plate overrides another plate the tension is released in the form of an earthquake. This occurs along the San Andreas Fault in California. Because the plates are merely moving past each other no new crust is formed or lost at this boundary.
Intended Learning Outcomes:
Instructional procedure: This lab works well as stations because the “Dynamic Planet” map, fault blocks, and US relief map need to be shared.
Activity 1: The Earth’s Major Tectonic Plates
Activity 2: Mountain Building
A. Fold Mountains – form at convergent boundaries, or within a plate between convergent boundaries.
B. Fault-block Mountains – form at divergent boundaries where two plates are moving and pulling apart. Many times this occurs along a fault line, which is a crack in the earth’s surface.
C. Dome Mountains – form from uplifting of a tectonic plate, not at a boundary. Magma under the earth rises and pushes up the crust to form a mountain without the eruption of the magma. The magma instead cools under the crust and forms the basis for the mountain.
D. Volcanic Mountains – usually form at convergent plates when a volcano puts out a series of eruptions over many years. The successive layers of lava that erupted out of the volcano form a mountain.
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