Study Guide & Educational Overview
### Core Geological Principles:
* **The Rock Cycle**:
* *Igneous*: Intrusive/plutonic (granite with coarse crystals) vs. extrusive/volcanic (basalt, obsidian glass, pumice).
* *Sedimentary*: Formed by deposition and lithification (limestone, sandstone, shale).
* *Metamorphic*: Recrystallized by heat and pressure (marble from limestone, slate from shale, gneiss with alternating bands).
* **Mineralogy**: Mohs Hardness Scale ranges from Talc (1) to Diamond (10); Quartz has hardness 7; Calcite exhibits double refraction (birefringence).
* **Plate Tectonics**: Divergent (Mid-Atlantic Ridge), Convergent/Subduction (Mariana Trench, Himalayas), Transform (San Andreas Fault); the Pacific "Ring of Fire" hosts over 75% of active volcanoes.
* **Seismology**: P-waves (compressional, travel through solids and liquids) arrive first; S-waves (transverse shear) cannot propagate through the liquid iron outer core.
* **The Rock Cycle**:
* *Igneous*: Intrusive/plutonic (granite with coarse crystals) vs. extrusive/volcanic (basalt, obsidian glass, pumice).
* *Sedimentary*: Formed by deposition and lithification (limestone, sandstone, shale).
* *Metamorphic*: Recrystallized by heat and pressure (marble from limestone, slate from shale, gneiss with alternating bands).
* **Mineralogy**: Mohs Hardness Scale ranges from Talc (1) to Diamond (10); Quartz has hardness 7; Calcite exhibits double refraction (birefringence).
* **Plate Tectonics**: Divergent (Mid-Atlantic Ridge), Convergent/Subduction (Mariana Trench, Himalayas), Transform (San Andreas Fault); the Pacific "Ring of Fire" hosts over 75% of active volcanoes.
* **Seismology**: P-waves (compressional, travel through solids and liquids) arrive first; S-waves (transverse shear) cannot propagate through the liquid iron outer core.
Frequently Asked Questions
The focus (or hypocenter) is the exact underground location where fault slip originates; the epicenter is the geographic point on Earth's surface directly above it.
A deadly, high-speed current of superheated gas, ash, and volcanic rock fragments racing down a volcano slope at speeds exceeding 400 km/h.
