Chapter 9 Earth’s Changing Surface Discover: What earth’s layers are. What causes earthquakes and volcanoes. How weathering and erosion change Earth’s surface. How minerals and rocks are identified.
Earthquake vibrations are used to study Earth’s layers because vibrations change speed and direction as they come in contact with various layers. Scientists can then infer characteristics of each layer. These vibrations are measured with a seismograph.
Lesson 2 What causes earthquakes and volcanoes?
The lithosphere is composed of sections called plates that shift in relation to one another.
There are three basic kinds of plate boundaries.
Converging boundary – Two plates collide, and mountains are made when the crust folds, tilts, and lifts as a result.
The rock cycle is a slow process during which rocks change from one type to another. Some rocks may change in thousands of years while others may take millions of years to change. An igneous rock forms after a volcanic eruption. After thousands of years of being exposed to high
temperatures and being squeezed, the igneous rock turns into metamorphic rock. Gradually, the metamorphic rock weathers into tiny bits of sediment. These pieces of sediment eventually form sedimentary rock after many layers of sediment are pressed together.