Chapter 1
Earth Science
Course: Elementary Education Multiple Subjects 7001
Subject: Elementary Education Science Subtest 7005
Chapter: Earth Science
The Earth system is a complex set of interrelated subsystems that are continuously changing. These changes are driven by internal energy (for example, geothermal heat) and external energy (for example, solar radiation). The major systems—geosphere (solid Earth), hydrosphere (water systems), and atmosphere (air systems)—engage in a constant exchange of matter and energy. Understanding these processes is crucial to explaining landform development, weather events, climate variability, and the cycling of natural resources.
1 Processes of the solid Earth (Geosphere)
1. Plate tectonics
Earth’s lithosphere is divided into rigid tectonic plates that float on the partially molten asthenosphere. These plates move slowly, averaging a few centimeters per year, due to mantle convection, ridge push, and slab pull mechanisms. Divergent plate boundaries involve plates moving apart. New oceanic crust is formed through seafloor spreading. Example: the Mid-Atlantic Ridge. Convergent boundaries occur where plates collide. Depending on the plates involved, this can result in subduction zones (such as oceanic-continental), volcanic arcs, or mountain building (such as continental-continental like the Himalayas). Transform boundaries involve plates sliding horizontally past each other. These zones accumulate stress that is released as earthquakes. Example: San Andreas Fault in California. These movements explain the distribution of earthquakes, volcanic activity, and mountain ranges. The theory of plate tectonics is a unifying framework for understanding Earth's geological history.