Science - 5th Grade
Standard 2 Objective 2
3 class periods of 45 minutes each
The Theory of Plate Tectonics is explored through the use of the Landform kit from the Utah Geological Survey. Students visualize the plates covering our earth by studying a map called the "Dynamic Planet". This map illustrates that earthquakes, volcanoes, and mountain building occurs predominantly at plate boundaries. By learning about the three types of plate boundaries, students model the four types of mountain building.
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.
The earth is a changing planet. The Theory of Plate Tectonics attributes earthquakes, volcanoes, the mountain-building process, and other movement to the interaction of the rigid plates forming the Earth's crust. The crust is composed of about 35 different large slabs of rock that move over the surface of hot, liquid magma (mantle) under the crust of our earth. These plates form puzzle pieces over the magma and interact with each other. Along the boundaries of these plates, interactions occur that create the Earth's seismic, mountain building, and volcanic activities. The interactions may form a divergent plate boundary, a convergent plate boundary, or a transforming plate boundary.
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.
1a. Observe simple objects, patterns, and events and report their observations.
1d. Compare things, processes, and events.
3a. Know and explain science information specified for the grade level.
4b. Describe or explain observations carefully and report with pictures,
sentences, and models.
5a. Cite examples of how science affects life.
Pre-lab discussion: Ask the students what major disaster happened in March of 2011. Remind them that it was the earthquake in Japan. Discuss with them some statistics from the earthquake: magnitude 9.0, occurred in the ocean 43 miles from shore, triggered tsunamis up to 130 feet high, 16,000 deaths, one of the 5 most powerful earthquakes to hit the world since 1900, and it occurred where the Pacific Plate is being pushed under another smaller plate and moved that smaller plate 8 feet to the east. After discussing this earthquake explain the theory of plate tectonics and go over the notes from the background information section.
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.
Rio Tinto Hands-on Science Curriculum Team