Oceans and Earth Science Study Review

Practice flashcards covering key topics, scientists, processes, and concepts for the upcoming oceanography and Earth science exam.

Ocean

A vast, continuous body of saline water that occupies major basins on Earth's crust, with an average depth of about $3682\,m$.

Sea

A smaller, shallower body of saline water that is partially enclosed by land and directly connected to an ocean.

Ocean vs. Sea (Comparison)

Oceans are immense, deep, open water reservoirs bounded by continents, whereas seas are smaller, shallower, and partially bordered by land.

Deepest region in the ocean

Challenger Deep in the Mariana Trench, reaching approximately $11034\,m$ ($36201\,ft$) below sea level.

Lowest dry land elevation on Earth

The shore of the Dead Sea, located at approximately $430\,m$ ($1410\,ft$) below sea level.

Deepest ocean region vs. lowest dry land (Comparison)

Challenger Deep plunges over $25$ times deeper below sea level ($11034\,m$) than the lowest exposed land at the Dead Sea ($430\,m$).

Pacific Navigators

Indigenous explorers who traveled across open ocean island chains without instruments by reading waves, stars, clouds, and winds.

European Navigators

Explorers driven by global trade routes who mapped ocean paths using navigational tools like the compass, astrolabe, and sextant.

Types of Ocean Explorers

Pacific navigators who used indigenous wayfinding, European navigators who charted trade routes with navigational tools, and modern scientific explorers who systematically measure ocean properties.

Ocean Exploration

The practical and scientific investigation of the ocean's physical, chemical, geological, and biological features using ships, diving equipment, and submersibles.

James Cook's Expedition

The first ocean voyage dedicated to systematic scientific research, accurately charting the Pacific using a marine chronometer.

Physical conditions measured by James Cook

Ocean depth soundings, water temperatures at varying depths, wind conditions, and current speeds and directions.

Submersible

A small specialized watercraft built to operate underwater and withstand high hydrostatic pressure for deep-sea exploration and research.

Human-Occupied Vehicle (HOV)

A deep-sea submersible that carries a crew of scientists directly to the ocean floor to make direct visual observations and collect samples.

Remotely Operated Vehicle (ROV)

An unmanned, tethered submersible controlled by operators on a surface ship to capture video and collect samples from the deep sea.

Autonomous Underwater Vehicle (AUV)

An untethered, programmable robotic submersible that independently navigates and collects ocean data without real-time human control.

Geological Oceanography

The study of the seafloor, ocean basin structure, marine sediments, and plate tectonics.

Chemical Oceanography

The study of the chemical composition, salinity, dissolved gases, and nutrients of seawater.

Physical Oceanography

The study of water motion, including currents, waves, tides, and thermal energy exchange with the atmosphere.

Biological Oceanography

The study of marine plants, animals, microbes, and their ecological interactions in oceanic environments.

Scientific Hypothesis

A tentative, testable, and falsifiable proposed explanation for an observed phenomenon.

Scientific Theory

A comprehensive, highly substantiated explanation of a natural phenomenon supported by a large body of empirical evidence.

Hypothesis vs. Theory (Comparison)

A hypothesis is a proposed, untested explanation, whereas a theory is thoroughly tested, verified, and widely supported by evidence.

Nebular Hypothesis

The model proposing that our solar system condensed from a giant rotating cloud of interstellar gas and dust roughly $4.6 \times 10^9\,years$ ago.

Proto-Earth Accretion

The process where colliding dust particles, rocks, and meteoroids coalesced through gravity to build the early planet.

Density Stratification

The gravitational separation of early molten Earth into layers: dense iron and nickel sank to form the core, while lighter silicates floated to form the mantle and crust.

Earth's Compositional Layers

The silicate crust, the silicate mantle (largest by volume), and the dense metallic iron-nickel core.

Lithosphere

The cool, rigid, brittle outermost physical layer composed of the crust and uppermost mantle, divided into tectonic plates.

Asthenosphere

The hot, plastic, ductile layer in the upper mantle beneath the lithosphere that can slowly deform and flow.

Lithosphere vs. Asthenosphere (Comparison)

The lithosphere is rigid and brittle, floating atop the deeper asthenosphere, which is ductile and semi-plastic.

Oceanic Crust

A thin ($5\,km$ to $10\,km$), dense ($\approx 3.0\,g/cm^3$) crust made primarily of dark volcanic rock called basalt.

Continental Crust

A thick ($30\,km$ to $50\,km$), lower-density ($\approx 2.7\,g/cm^3$) crust made primarily of light-colored rock called granite.

Oceanic Crust vs. Continental Crust (Comparison)

Oceanic crust is thinner, denser, and basaltic; continental crust is thicker, lighter, and granitic.

Isostatic Adjustment

The vertical rising or sinking of Earth's crust to maintain buoyant equilibrium within the underlying plastic mantle.

Origin of Earth's atmosphere

Volcanic outgassing emitted water vapor, carbon dioxide, methane, and ammonia, creating an early atmosphere with virtually no free oxygen.

Origin of Earth's oceans

Cooling of the planet allowed outgassed water vapor to condense, producing torrential rains over millions of years that accumulated in low basins.

Stanley Miller Experiment

A laboratory apparatus simulating prebiotic Earth that used electric sparks on basic gases to synthesize organic amino acids.

Evolution by Natural Selection

The process where individuals with favorable inherited traits are more likely to survive, reproduce, and pass those traits to offspring.

Photosynthesis

The process using sunlight, carbon dioxide, and water to produce sugar and oxygen: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.

Cellular Respiration

The process breaking down glucose in the presence of oxygen to release usable cellular energy ($\text{ATP}$), carbon dioxide, and water: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$.

Great Oxidation Event

The sudden rise in atmospheric oxygen caused by early photosynthetic cyanobacteria around $2.4 \times 10^9\,years$ ago.

Oxygen and Mass Extinctions

Rapid depletion of dissolved oxygen (oceanic anoxia) suffocates marine life, causing widespread global die-offs in Earth's history.

Radiometric Dating

A technique that determines the numerical age of rocks by measuring the ratio of radioactive parent isotopes to stable daughter products.

Half-Life

The time required for half of the radioactive atoms in a sample to decay into daughter atoms.

Geologic Time Scale

A calendar dividing Earth's $4.6 \times 10^9\,year$ history into eons, eras, periods, and epochs based on rock strata and fossil records.