Physical Geology and Solar System Flashcards

Comprehensive vocabulary flashcards covering lecture topics in physical geology, plate tectonics, planetary geology, bolide impacts, atomic structure, and mineralogy.

Perseverance

A NASA Mars probe launched to land in an ancient lake basin on Mars in February 2021, carrying a miniature helicopter drone to search for evidence of ancient Martian life.

Hypothesis

A tentative, testable explanation proposed by scientists to account for observed natural phenomena, requiring data collection for empirical testing.

Theory

A well-substantiated scientific explanation supported by extensive empirical data and repeated testing, which must remain falsifiable and subject to ongoing evaluation.

Asthenosphere

A weak, semi-plastic, and malleable region of the upper mantle situated directly beneath the rigid lithosphere.

Lithosphere

The brittle outer sphere of Earth that encompasses both the crust and the solid uppermost mantle.

Oceanic Crust

The dense outer crustal layer underlying the ocean basins, chemically enriched in iron ($Fe$) and magnesium ($Mg$).

Continental Crust

The thick, buoyant outer crustal layer enriched in silicon, aluminum, sodium, and potassium that floats high relative to underlying layers.

Continental Drift Hypothesis

The hypothesis proposed in 1912 by Alfred Wegener proposing that modern continents were once united as the supercontinent Pangaea before drifting apart.

Seafloor Spreading Hypothesis

The hypothesis advanced by Harry Hess in the 1950s stating that oceanic crust pulls apart along mid-ocean ridges as upwelling mantle magma solidifies and records magnetic reversals.

Plate Tectonic Theory

A unifying geological theory formulated in the mid-1960s that integrates continental drift and seafloor spreading to explain mountain building, volcanism, and seismic activity.

Divergent Margin

A tectonic plate boundary where plates pull apart under tensional stress, forming continental rift valleys and mid-ocean ridges.

Convergent Margin

A tectonic plate boundary where plates collide under compressional stress, resulting in subduction or continental collision.

Subduction

The process where a denser oceanic plate bends and descends beneath a less dense continental or oceanic plate into the mantle.

Volcanic Island Arc

A curved chain of volcanic islands formed above an oceanic-oceanic subduction zone due to mantle melting above the subducting plate.

Transform Margin

A tectonic plate boundary where plates slide past one another horizontally without creating or destroying crust, such as the San Andreas Fault.

Epicenter

The point on the surface of the Earth directly above the subsurface focus where earthquake energy is released.

Terrestrial Planets

The four small, dense, rocky inner planets (Mercury, Venus, Earth, and Mars) composed predominantly of refractory elements.

Jovian Planets

The four large, low-density outer gas giants (Jupiter, Saturn, Uranus, and Neptune) composed primarily of volatile elements.

Refractory Elements

High-melting-point elements and compounds (such as iron, silicon, aluminum, and magnesium) capable of remaining solid near intense solar heat.

Volatile Elements

Elements and compounds with low melting points (such as atmospheric gases and ices) that evaporate or destabilize at high temperatures near a heat source.

Plane of the Ecliptic

The primary orbital geometric plane in space along which the major planets of the solar system revolve around the Sun.

Solar Nebula Hypothesis

The model proposing that the Sun and planets condensed under gravity from a rotating cloud of interstellar nebular gas and space dust.

Bolide

A general scientific term for an impacting extraterrestrial body or upper-atmosphere atmospheric explosion when its specific nature is unknown.

Ejecta Blanket

The deposit of rock fragments, mineral spherules, and debris ejected from an impact crater during a bolide impact.

Shock Metamorphism

Deformation and alteration of target rocks and minerals caused by extreme impact pressures and temperatures during a high-velocity bolide collision.

Chesapeake Bay Impact Crater

A buried, approximately $100\,km$-wide marine impact structure at the tip of the Delmarva Peninsula formed $35\text{ million}$ years ago.

Atomic Number

The total number of positively charged protons present inside the nucleus of an atom.

Atomic Mass

The sum total of protons and neutrons contained within the nucleus of an atom.

Isotopes

Atoms of the same element containing equal numbers of protons but differing numbers of neutrons in their nuclei.

Cation

A positively charged ion formed when an atom loses one or more negative electrons.

Anion

A negatively charged ion formed when an atom gains one or more negative electrons.

Ionic Bonding

A chemical bond formed by the electrostatic attraction between oppositely charged cations and anions following the complete transfer of electrons.

Covalent Bonding

A chemical bond formed when adjacent atoms share outer electrons to satisfy electron shell stability.

Mineral

A naturally formed solid possessing an ordered internal crystal structure and a definite chemical composition.

Mohs Hardness Scale

A relative ranking scale from $1$ (talc) to $10$ (diamond) used to evaluate mineral scratch resistance and bond strength.

Mineral Cleavage

The structural tendency of a mineral to break along defined, repeated planes of internal atomic weakness.

Conchoidal Fracture

A smooth, shell-like fracture pattern characteristic of minerals or glasses (such as quartz) lacking preferred planes of atomic weakness.

Luster

The physical appearance of light reflected off the surface of a mineral, classified broadly as metallic or nonmetallic.

Silicate Mineral Group

The most abundant family of rock-forming minerals, comprising approximately $95\%$ of Earth's rock-forming minerals.

Silica Tetrahedron

The fundamental complex anion ($SiO_4^{4-}$) building block of silicate minerals, consisting of one central silicon cation ($Si^{4+}$) bound to four surrounding oxygen anions ($O^{2-}$).