Earth Science: Igneous, Volcanic, Sedimentary, and Metamorphic Processes

A complete set of vocabulary flashcards covering the Rock Cycle, Igneous, Sedimentary, and Metamorphic rock classifications, volcanic structures, and weathering processes as detailed in the lecture notes.

Rock

Naturally formed, consolidated material usually composed of one or more minerals.

Intrusive (Plutonic)

Igneous rock that solidifies below Earth's surface and cools slowly.

Aphanitic

Fine-grained igneous texture where crystals are too small to see due to rapid cooling.

Pegmatitic

Extremely coarse-grained igneous texture with crystals $> 5\,cm$.

Porphyritic

Texture characterized by two distinct crystal sizes with large phenocrysts in a fine groundmass.

Vesicular

Texture containing gas-filled cavities or bubbles, such as in pumice or scoria.

Felsic

Chemical composition containing $> 65\%$ $SiO_2$, resulting in light-colored rocks like Granite and Rhyolite.

Ultramafic

Chemical composition containing $< 45\%$ $SiO_2$, resulting in very dark or green ferromagnesian rocks like Peridotite.

Decompression Melting

Melting occurs when mantle material moves upward to lower pressure zones.

Flux Melting

Process where the addition of hot water vapor lowers the melting point of rocks by $> 200^{\circ}C$.

Dike

A shallow intrusion that cuts across existing rock layering in a vertical or tabular fashion.

Sill

A shallow intrusion that runs parallel to existing rock layering in a horizontal or tabular fashion.

Batholith

A massive deep intrusion with $> 100\,km^2$ surface exposure.

Viscosity

Resistance to flow; high levels are associated with high silica and explosive eruptions.

Pahoehoe

A lava flow characterized by a smooth, ropy texture.

Columnar Jointing

Parallel, six-sided vertical columns formed by cooling contraction in lava.

Pyroclastic Flow

A high-speed, lethal mixture of hot gas, ash, and rock fragments with temperatures $> 800^{\circ}C$.

Shield Volcano

Broad, gently sloping, very large volcano formed by low-viscosity basaltic lava like Mauna Loa.

Composite (Stratovolcano)

Cone-shaped volcano with alternating layers of lava and pyroclastics, known for being highly explosive.

Caldera

A large volcanic depression formed by collapse after a massive eruption, such as the Apolaki Caldera.

Lahar

A volcanic mudflow caused by volcanic ash mixing with water or rain.

Weathering

The breakdown of rocks and minerals at Earth's surface.

Frost Wedging

Mechanical weathering where water freezes in cracks, expands, and splits rock.

Hydrolysis

Chemical weathering where water reacts with minerals, such as the transformation of Feldspar into Kaolinite clay.

Lithification

The process of turning loose sediment into solid rock via compaction and cementation.

Breccia

A detrital sedimentary rock formed from angular grains.

Evaporites

Chemical sedimentary rocks formed via water evaporation, such as Rock Salt or Rock Gypsum.

Cross-Bedding

Inclined layers within a sedimentary bed indicating sand dunes or river ripples.

Transgression

A sea-level change where the sea level rises and the coastline moves landward.

Foliated

Metamorphic texture with a planar or layered arrangement of aligned minerals caused by differential stress.

Gneiss

A high-grade foliated metamorphic rock characterized by banded light and dark mineral layers.

Contact (Thermal) Metamorphism

Metamorphism driven by high temperature near magma intrusions, often occurring in a zone called an aureole.

Migmatite

A rock representing the final stage of prograde metamorphism where partial melting occurs.