Igneous Rocks
Rock Textures & Cooling History
Tectonic Settings & Melting Mechanisms
Composition & Minerals
Surface Processes & Human Impact
100

This main type of magma/lava cooling occurs below the surface, creating coarse-grained rocks with large minerals.

What is intrusive cooling?

100

This coarse-grained texture forms when magma cools slowly deep underground, allowing large interlocking crystals to grow visible to the naked eye.

What is Phaneritic?

100

This type of melting occurs at divergent plate boundaries and hotspots when rising mantle material experiences reduced pressure.

What is decompression melting?

100

Magmas high in silica and lighter in color that tend to be more viscous and explosive are classified as this.

What is felsic?

100

The original rock or sediment from which a soil develops and inherits its nutrient composition is known by this term.

What is Parent material?

200

Known for its light color and chunky texture, this intrusive felsic rock contains quartz and orthoclase feldspar.

What is Granite

200

This texture features large crystals called phenocrysts suspended in a finer-grained matrix, resulting from a two-stage cooling history.

What is porphyritic?

200

The two primary sources of internal heat that keep Earth's mantle hot and moving are residual heat from formation and this sub-surface nuclear process.

What is radioactive decay?

200

Dark-colored igneous rocks like basalt and gabbro are classified as this because they are rich in iron and magnesium.

What is mafic?

200

Soils formed from basalt are often more fertile than granite-derived soils because basalt weathers into this nutrient-retaining mineral.

What is Clay?

300

Described as "dark," coarse-grained, and the brother to granite, this intrusive rock contains no quartz.

What is Gabbro?
300

This texture, common in obsidian, results when lava cools so rapidly on the surface that mineral crystals do not have time to form.

What is glassy?
300

At subduction zones, water and volatiles released from the oceanic plate lower the melting point of the mantle wedge in a process known as this.

What is flux melting?

300

Minerals formed at higher temperatures tend to weather at this speed relative to minerals formed at lower temperatures.

What is faster?

300

Igneous rocks like granite and basalt are frequently quarried for construction to serve as this building material.

What is Crushed stone / Aggregates?

400

Trapping air vesicles during rapid cooling, this felsic extrusive rock has such a low density that it can float on water.

What is pumice?

400

Trapped gas bubbles in solidifying volcanic rocks like pumice or scoria create this porous, sponge-like texture.

What is vesicular?

400

Hawaiian volcano chains and flood basalts are typically formed by this specific localized upwelling melting process.

What is hotspot melting?

400

Because of its high resistance to chemical weathering, this mineral commonly found in granite persists as sand in granite-derived soils.

What is quartz?

400

Highly fractured or vesicular volcanic rocks are important water resources because they can store and transmit this subterranean liquid.

What is groundwater?

500

This fine-grained, mafic extrusive rock is commonly found in Hawaii and features "aa" and "pahoehoe" lava types.

What is basalt?

500

Fine-grained extrusive rocks like basalt exhibit this texture where mineral grains are too small to be seen with the naked eye.

What is anaphitic?

500

The subduction of an oceanic plate leads to flux melting that typically generates these types of volcanic arc structures and stratovolcanoes.

What are volcanic arcs?

500

Mafic minerals like olivine and pyroxene release these two essential plant nutrient cations during rapid weathering.

What are calcium and magnesium?

500

Rapid chemical weathering of mafic rocks builds clay soils quickly, but on steep slopes, saturated clay can increase the risk of this natural geohazard.

What is Mass wasting / Landslides?

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