Plate Tectonics, Earth Systems, and the Rock Cycle
Earth and Space Science comprises ~20% of the Science exam.
Plate Tectonics & Boundary Types
Earth's lithosphere is divided into tectonic plates floating on the asthenosphere:
- Convergent Boundaries (Colliding): Plates push together. Causes mountain formation (continental-continental) or subduction zones, deep ocean trenches, and volcanic arcs (oceanic-continental).
- Divergent Boundaries (Separating): Plates pull apart. Causes seafloor spreading and mid-ocean ridges.
- Transform Boundaries (Sliding): Plates slide horizontally past one another. Causes earthquakes (e.g., San Andreas Fault).
The Three Rock Families
- Igneous: Formed from cooled magma/lava (Basalt, Granite).
- Sedimentary: Formed from compacted sediments and fossils over millions of years (Limestone, Sandstone).
- Metamorphic: Formed from intense heat and pressure altering existing rock (Marble, Slate).