Chapter 1
Earth Science
Course: Elementary Education Multiple Subjects 5001
Subject: Elementary Education Science Subtest 5005
Chapter: Earth Science
1. Processes of the Solid Earth (Geosphere)
The geosphere is constantly in motion due to internal heat and gravitational forces. These processes work over long periods and drive the formation and destruction of Earth’s surface features.
a. Internal processes
These originate beneath Earth’s surface and include:
- Plate tectonics: The Earth’s lithosphere is broken into rigid tectonic plates that float on the semi-fluid asthenosphere. These plates move due to convection currents in the mantle.
Seafloor spreading: At mid-ocean ridges (e.g., Mid-Atlantic Ridge), magma rises, creating new oceanic crust.
Subduction zones: When an oceanic plate slides beneath a continental plate (e.g., Peru-Chile Trench), it forms trenches and volcanic arcs.
Continental collision: When two continental plates converge, mountain ranges like the Himalayas are formed.
Transform faults: Plates slide past each other horizontally, creating earthquakes (e.g., San Andreas Fault).
- Seafloor spreading: At mid-ocean ridges (e.g., Mid-Atlantic Ridge), magma rises, creating new oceanic crust.
- Subduction zones: When an oceanic plate slides beneath a continental plate (e.g., Peru-Chile Trench), it forms trenches and volcanic arcs.
- Continental collision: When two continental plates converge, mountain ranges like the Himalayas are formed.
- Transform faults: Plates slide past each other horizontally, creating earthquakes (e.g., San Andreas Fault).
- Earthquakes: Caused by sudden release of energy from tectonic stress. Seismic waves radiate outward from the focus. The point on the surface directly above is called the epicenter.
- Volcanism: Magma reaches the surface through weak points in the crust, forming volcanoes. Volcanic eruptions release gases (like CO₂ and SO₂), ash, and lava that can alter climate and landforms.
- Isostasy and mountain uplift: Earth's crust can rise (isostatic rebound) when heavy ice sheets melt, causing changes in elevation and landscape.