The lower region is part of the asthenosphere and is referred to as "fluid," which is not in reference to its phase of matter, but rather to the plasticity of the asthenosphere. The upper region is part of the lithosphere it is very rigid and exists as the bottom of our tectonic plates. For our purposes, 1 centimeter will equal 1,000 kilometers.Ī commonly held misconception is that the Earth's mantle is liquid because we refer to the lower portion of it as being "fluid." However, the most widely accepted current scientific understanding is that the mantle is solid. In this activity, we will make a model of the Earth's layers. Building scale models of the Earth can help engineers plan the routes and orbits of space flights, or design instruments that help predict earthquakes, or invent robots to travel into the different layers to collect data. Engineers sometimes build detailed scale models of objects to observe how parts fit together and/or move. For example, perhaps 1 inch corresponds to 1 foot. It is measured to a "scale" that corresponds to the actual size. A scale model has the same shape and components and relative proportions as the actual object. Or a toy car as a smaller scale model of a full-size car. You could think of a doll as a smaller scale model of a person. It is made to be the same as the original object but at a different size than the real object. Who can tell me what a "scale model" is? (Listen to student ideas.) A scale model is a smaller or larger version of an object. In the crust layer, sometimes the plates collide, or stick together, and when this happens, earthquakes occur. Even in high-pressure and high-temperature conditions, it can move (deform) only very slowly, perhaps a few centimeters a year. Some scientists describe it as having the consistency of warm wax or warm asphalt, or even silly putty. The solid crust "floats" along in plates very slowly on top of the mantle. Can you guess why? (Listen to student ideas.) Well, if we tried to travel all the way to the Earth's inner core, we would be crushed into pieces from the very high pressure, and be burned up from the extreme heat! It is not a friendly environment for humans. Most research about the Earth comes from studying the crust. The inner core, outer core and mantle experience extremely high pressures and temperatures. The crust is the thinnest layer of the Earth and is the layer on which we live. (Draw Figure 1 on the classroom board, or show students a suitable diagram or projected image.) The inner core, mantle and crust are solid, and the outer core is molten, or liquid. The Earth is a sphere made of several layers: the inner core, outer core, mantle and crust.
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