Earth and Space Science: Earth's Structure, Rocks, and Space
What you must understand
Earth has layers: crust, mantle, outer core, inner core. The outer core is liquid; the inner core is solid. Know plate tectonics: Earth's lithospheric plates move over the mantle, causing earthquakes, volcanoes, and mountain building at plate boundaries (divergent, convergent, transform).
The rock cycle links three rock types: igneous (cooled magma or lava), sedimentary (compacted and cemented sediments, often layered, may contain fossils), and metamorphic (changed by heat and pressure). Know that weathering breaks rock down, erosion moves it, and deposition lays it down.
In space, understand that Earth's rotation causes day and night, and its revolution around the Sun plus axial tilt causes seasons. Know the order of planets, that the Moon orbits Earth and shows phases, and that gravity keeps planets in orbit. The Sun is a star; stars differ in size, color, and temperature.
Traps to expect
Questions often blame distance from the Sun for seasons - the cause is axial tilt. Another trap is confusing rotation with revolution, or calling sedimentary rock "melted." Watch for statements that the Moon produces its own light - it reflects sunlight. Also check whether a process is weathering (breakdown in place) or erosion (transport).
Worked example / rule of thumb
A rock with visible layers and a fossil is most likely sedimentary, because layers form from deposited sediments and fossils are preserved in them. Rule of thumb: ask what process formed the rock - cooling, deposition, or heat and pressure.
Key ideas
- Earth's layers and their states
- Plate boundaries and resulting landforms
- The three rock types and the rock cycle
- Weathering, erosion, and deposition
- Rotation, revolution, tilt, and Moon phases