Geology: Earthquakes, Minerals, Rocks, and Geologic Time

Vocabulary practice flashcards covering earthquakes, mineral groups and properties, the rock cycle, depositional environments, fossils, metamorphism, volcanism, stratigraphic principles, and geological time eons.

Seismographs

Instruments that record ground motion using waves, used to learn where or when (not exactly when) an earthquake can occur.

Magnitude

A description of an earthquake based on the amount of ground motion measured on a seismograph.

Modified Intensity Scale

A scale that describes the damage and human interaction when an earthquake occurs.

Liquefaction

An earthquake hazard in which sediment shaking liquifies the ground into water.

Seismic Gaps

Active faults or tectonic plates that have not experienced major earthquakes in an unusually long time compared to neighboring segments.

Streak

The color of the line produced when a mineral is rubbed on a surface, representing the true color of the rock.

Cleavage

Smooth planes along which a mineral breaks.

Fracture

The way a mineral breaks when it does not break along smooth planes.

Polymorphs

Minerals that share the same chemical composition but possess different bonds.

Silicate

A mineral group characterized by chemical formulas ending in $\text{Si}_x\text{O}_x$.

Oxide

A mineral group characterized by chemical formulas ending in $\text{O}_x$.

Sulfide

A mineral group characterized by chemical formulas ending in $\text{S}_x$.

Sulfate

A mineral group characterized by chemical formulas ending in $\text{S}_x\text{O}_x$.

Halide

A mineral group characterized by formulas ending in fluorine, chlorine, bromine, or iodine (F, Cl, Br, I).

Carbonate

A mineral group characterized by chemical formulas ending in $\text{C}_x\text{O}_x$.

Phosphate

A mineral group characterized by chemical formulas ending in $\text{P}_x\text{O}_x$.

Native Elements

Singular elements that stand by themselves, other than F, Cl, Br, and I.

Silicate Tetrahedron

$\text{Si}_x\text{O}_x$ structure that serves as the building block of the crust and mantle.

Feldspars

Silicate minerals that are very commonly found in the crust.

Decompression Melting

The melting of rock caused by taking away pressure, such as when rock rises upward in the mantle.

Fluid-induced Melting

Melting that happens along subduction zones where water is released.

Conduction Melting

Melting that occurs when magma contacts surrounding rocks that have low melting points.

Sills

Horizontal igneous rock intrusions.

Dikes

Vertical igneous rock intrusions.

Plutons

Giant rocks formed when magma gets trapped underground and cools over a long time, later revealed when the surface erodes.

Bedding

Distinct layers of sediment that can be distinguished from one another.

Cross-bedding

Angled sediment layers caused by the movement of sediment.

Graded-bedding

Changes in grain size from the bottom to the top within a single sediment bed.

Basins

Areas where sediment can be collected.

Body Fossils

Fossilized remains of prehistoric plants and animals.

Trace Fossils

Fossilized signs or evidence of prehistoric plants and animals.

Subfossils

Fossils that are not fully mineralized because the fossilization process was not completed.

Foliation

Layering in metamorphic rocks formed when minerals are affected by shear stress or directional pressure.

Contact Metamorphism

Metamorphism that occurs when magma heats up surrounding rock under conditions of high temperature and low pressure.

Viscosity

A fluid's resistance to flow or thickness, such as low viscosity in water versus high viscosity in tar.

Shield Volcano

A volcano with a shape formed by low-viscosity lava that allows the lava to flow.

Cinder Cone

A type of volcano that only erupts once and then never again.

Stratovolcano

A volcano where lava layers build on top of each other from periodical eruptions.

Pyroclastic Flows

Very hot and fast clouds of volcanic gases and ash that are lethal.

Lahars

Massive amounts of built-up, hot, moving volcanic material sliding down a slope.

Principle of Original Horizontality

The geological principle stating that sediments tend to accumulate horizontally.

Principle of Superposition

The geological principle stating that in undeformed rock layers, younger rocks are on top and older rocks are below.

Principle of Lateral Continuity

The geological principle observing that rock layers often form in extensive horizontal sheets.

Principle of Cross-cutting Relations

The geological principle stating that features cutting across rock units are older than the fault cutting them.

Principle of Baked Contact

The geological principle observing that an igneous intrusion cooks the invaded surrounding rock.

Principle of Inclusion

The geological principle stating that inclusions are always older than the enclosing material.

Principle of Fossil Succession

The principle describing the predictability of fossil distribution through time, with oldest fossils at the bottom and youngest at the top.

Unconformity

A gap in the rock record representing a period of non-deposition and possible erosion.

Nonconformity

An unconformity where igneous or metamorphic rocks are capped by sedimentary rocks.

Disconformity

An erosion surface between sedimentary layers where intermediate rock layers go missing.

Stratigraphic Correlation

The process of matching rock columns across distances based on rock types that look the same.

Hadean

The earliest and longest eon, marked by an early molten earth, differentiation, and the formation of the magnetic field and moon.

Archean

The eon marked by the beginning of tectonic activity, the appearance of the first oceans, and the Great oxidation event.

Proterozoic

The eon during which animals, plants, and fungi started to appear as first multicellular life, and the oldest continental crust formed.

The Great Dying

A mass extinction event in the Paleozoic Era caused by a volcanic eruption that impacted Earth and wiped out many species.

K-Pg Extinction

A mass extinction event during the Mesozoic Era caused by a huge asteroid.