Rock Solid
Rocks cover the earth's surface, including what is below or near human-made structures. With rocks everywhere, breaking rocks can be hazardous and potentially disastrous to people. Students are introduced to three types of material stress related to rocks: compressional, torsional and shear. They learn about rock types (sedimentary, igneous and metamorphic), and about the occurrence of stresses and weathering in nature, including physical, chemical and biological weathering.
Talus Cones in Glen Canyon, AZ. This formation was made from rock falls, which are when weathering breaks rocks from the surface of a cliff.Copyright NOAA http://www.ngdc.noaa.gov/seg/cdroms/geohazards_v3/document/647006.htm
Geotechnical engineers study rocks in the earth's crust. They conduct tests and simulations to predict volcanoes, earthquakes and rockslides. To avoid potential disasters that might occur if rocks fail, engineers routinely apply their understanding of rocks and soils prior to the construction of complex and costly structures such as airports, roads, dams, skyscrapers and tunnels. They identify underground rock types and predict their behavior under stress, as well as determine the best way to excavate them as part of the construction process.
After this lesson, students should be able to:
- Describe the basic ideas of stress.
- List the three different types of weathering.
- Explain that not all rocks break the same way or with the same amount of pressure.
- Describe how engineers are able to evaluate the strength of rocks.
- Develop a model of the rock cycle