EVSC 206 MT1

Coastal Marine Science

Study of the physical, chemical, biological, and geological processes in coastal and marine environments, including how oceans interact with land and atmosphere.

Oceanography

The scientific study of the ocean, including its currents, chemistry, geology, and ecosystems. “Ocean” = marine environment; “graphy” = description.

Nebular Hypothesis

Theory that the solar system formed from a rotating cloud of gas and dust (solar nebula) that flattened into a disk, forming the Sun and planets.

Proto-Earth (Early Earth)

A young, homogenous planet that gradually differentiated into layers through heat, impacts, and gravity; later formed oceans via outgassing and condensation.

Density Stratification

Separation of Earth’s layers by density: heavy elements sink to the core, lighter ones form crust and atmosphere.

Lithosphere

Rigid outer shell (crust + upper mantle) that breaks into moving tectonic plates.

Asthenosphere

Plastic, semi-fluid upper mantle layer beneath the lithosphere that allows tectonic plates to move.

Mesosphere

Region of more rigid mantle rock below the asthenosphere; transmits seismic waves efficiently.

Inner & Outer Core

Inner = solid iron-nickel; outer = liquid iron-nickel. Movement here generates Earth’s magnetic field

Radioactive Decay (Internal Heat Source)

Breakdown of unstable elements (e.g., uranium, thorium) releases heat, driving mantle convection and plate tectonics.

Oceanic vs Continental Crust

Oceanic: dense, basaltic, recycled often.
Continental: less dense, granitic, older and more stable.

Nucleogenesis

Formation of new atomic nuclei within stars by nuclear fusion, producing heavier elements that later formed Earth’s matter.

Hadeon Eon

Earliest eon (4.6–4.0 Ga) — formation of Earth, differentiation, and atmosphere by outgassing.

Archean Eon

Eon of first oceans and continents; life begins in hydrothermal settings.

Proterozoic Eon

“Great Oxidation Event”: cyanobacteria photosynthesize, increasing O₂ and enabling multicellular life.

Phanerozoic Eon

Eon of abundant, complex multicellular life beginning ~ 541 Ma.

Outgassing

Release of gases (water vapour, CO₂) from Earth’s interior during volcanic activity — source of atmosphere and ocean water.

Salinity Formation

Rain dissolved minerals from crustal rocks; ions accumulated in oceans forming a stable salinity balance.

Hydrothermal Vents

Hot, mineral-rich seafloor springs near spreading ridges; support chemosynthetic life independent of sunlight.

Chemosynthesis

Biological conversion of chemical energy (H₂S, CH₄) into organic matter; used by vent microbes

Heterotrophs & Autotrophs

Heterotrophs = consume organic matter; Autotrophs = produce it (via photo- or chemosynthesis).

Stromatolites

Layered microbial reefs built by photosynthetic cyanobacteria; evidence of early life (~3.4 Ga).

Great Oxidation Event

Increase in atmospheric oxygen (2.4 Ga) from photosynthetic cyanobacteria; killed many anaerobes and diversified life.

Carbon Isotopes (¹²C, ¹³C, ¹⁴C)

Different carbon forms used to trace biological activity, date materials, and study ocean–atmosphere carbon exchange.

Isotope

Atoms of same element with different neutron numbers; useful for dating and tracing geochemical processes.

δ¹³C (Carbon-13 Ratio)

Isotopic signature showing biological carbon cycling; lighter ¹²C = photosynthetic activity.

Carbon-14 (Radiocarbon)

Radioactive isotope used to date organic matter and measure ocean ventilation times.

Stanley Miller Experiment

1953 test showing that amino acids can form abiotically under early-Earth conditions — evidence for “prebiotic soup.”

Hydrothermal Vent Hypothesis

Theory that life originated near hydrothermal vents where chemical gradients and heat supported first metabolism.

Coast Salish Creation Story

Indigenous narrative explaining the creation of landforms and human traits; connects geology with cultural heritage.

Ganymede

Jupiter’s largest moon with internal ocean—possible analog for Earth’s subsurface water and extraterrestrial life studies.

Ocean Composition

97.2 % of Earth’s water is oceanic; only ~ 1 % is available freshwater.

Pacific Ocean Depth

Deepest point ≈ 11,022 m (Mariana Trench); contrasts with Everest (8,848 m).

“Planet Ocean” Concept

Emphasizes that Earth’s dominant surface feature is water, not land; oceans regulate life and climate.

Continental Drift

The theory proposed by Alfred Wegener that continents have moved over geological time and were once joined in a single supercontinent, Pangaea. Supported by matching fossils, rock types, and coastlines.

Pangaea

The supercontinent that existed about 200 million years ago before breaking apart into today’s continents. Surrounded by a global ocean called Panthalassa.

Panthalassa

The vast global ocean that surrounded Pangaea during the late Paleozoic and early Mesozoic eras.

Plate Tectonics

Theory that Earth’s lithosphere is divided into tectonic plates that move over the asthenosphere due to convection in the mantle.

Lithosphere

The rigid outer layer of the Earth (crust + upper mantle) that moves as tectonic plates.

Asthenosphere

A ductile (plastic) region beneath the lithosphere that allows plate movement through slow convection

Convection Currents

Circular motions within Earth’s mantle caused by heat from the core; drive movement of tectonic plates.

Seafloor Spreading

The formation of new oceanic crust at mid-ocean ridges where magma rises, cools, and pushes older crust aside.

Mid-Ocean Ridge

An underwater mountain chain formed by divergent tectonic plates and seafloor spreading (e.g., Juan de Fuca Ridge).

Subduction Zone

A convergent boundary where a denser oceanic plate sinks beneath a less dense plate, forming deep trenches and volcanoes.

Convergent Boundary

Where two tectonic plates collide. One may subduct beneath the other, causing mountain building, earthquakes, and volcanism.

Divergent Boundary

Where tectonic plates move apart, creating new crust through upwelling magma (e.g., mid-ocean ridges).

Transform Boundary

Where plates slide horizontally past each other, producing shallow earthquakes (e.g., San Andreas Fault).

Juan de Fuca Plate

A small oceanic plate off the coast of British Columbia that subducts beneath the North American Plate at the Cascadia Subduction Zone.

Cascadia Subduction Zone.

A convergent boundary extending 1,100 km along the Pacific Northwest coast; source of megathrust earthquakes and tsunamis

Ring of Fire

A horseshoe-shaped zone encircling the Pacific Ocean where ~75% of Earth’s volcanoes and ~90% of earthquakes occur.

Subduction

Process of one tectonic plate sinking beneath another into the mantle, where it melts and is recycled.

Megathrust Earthquake

Massive earthquakes (M8–9) occurring at subduction zones due to stress release along locked plate boundaries (e.g., 1700 Cascadia event).

Convection Cell

A circular pattern of rising hot material and sinking cooler material in the mantle that drives tectonic plate motion.

Reverse Fault (Thrust Fault)

A type of fault where the hanging wall moves upward relative to the footwall, typical of subduction zones.

Ocean Trench

A deep, narrow depression in the seafloor formed at subduction zones where one plate descends beneath another.

Transform Fault

A boundary where plates grind past one another horizontally without creating or destroying crust.

Ocean Basin

Depression on the seafloor created by divergent and convergent processes; holds the world’s oceans.

Volcanic Arc

A chain of volcanoes formed above a subducting plate, often parallel to a trench (e.g., Cascade Range).

Mantle Plume

Localized upwelling of hot rock from deep in the mantle that can create volcanic islands (e.g., Hawaii).

Hydrothermal Vent

A fissure in the seafloor emitting heated, mineral-rich water formed near mid-ocean ridges; supports chemosynthetic life.

Black Smokers

Hydrothermal vents releasing hot (350–400°C), dark, sulphide-rich fluids; support unique ecosystems.

White Smokers

Hydrothermal vents emitting cooler (200–300°C), light-colored plumes of minerals like barium, calcium, and silicon.

Deep-Sea Chimneys

Mineral towers formed by the precipitation of metals as superheated vent fluids mix with cold seawater.

Earthquake

The release of energy due to sudden movement along faults in the crust, often at plate boundaries.

Shallow-Focus Earthquake

Occurs near the Earth’s surface (0–70 km deep), often at divergent or transform boundaries.

Deep-Focus Earthquake

Occurs at greater depths (300–700 km), typically in subduction zones as descending plates deform.

Cascadia Megathrust Earthquake (1700 CE)

An estimated M8.7–9.2 earthquake along the Cascadia Subduction Zone; evidence includes tsunami deposits and “ghost forests.”

Ghost Forests

Stands of dead trees killed by sudden land subsidence and saltwater intrusion after large earthquakes or tsunamis.

Tsunami

A series of large ocean waves caused by sudden seafloor displacement (e.g., earthquakes, landslides, or eruptions).

Sea Floor Age

The seafloor is geologically young—no older than 180 million years—because it is continually created and recycled.

Youthful Ocean Floor

Refers to the relatively recent formation of ocean crust due to continuous seafloor spreading and recycling.

Cascadia Trench

A deep subduction trench off the Pacific Northwest coast where the Juan de Fuca Plate descends beneath the North American Plate.

Ore Deposit Formation at Vents

Hydrothermal vents deposit metal-rich sulfides that can form valuable mineral resources on the seafloor.

Plate Recycling

The ongoing process of new crust forming at mid-ocean ridges and old crust being destroyed at subduction zones—keeps Earth’s size constant.

Water Molecule (H₂O)

Two hydrogen atoms covalently bonded to one oxygen atom at a 105° angle, giving water polarity and its unique physical properties.

Covalent Bond

A chemical bond formed by sharing electrons between atoms; in water, it holds hydrogen and oxygen together strongly.

Polarity

A molecule’s unequal charge distribution. Water’s positive (H) and negative (O) ends make it dipolar, allowing it to dissolve many substances.

Hydrogen Bond

Weak electrostatic bond between water molecules; causes cohesion, high surface tension, and high heat capacity.

Dipolar Molecule

A molecule with partial positive and negative charges (like water), enabling hydrogen bonding and strong solvent power.

Cohesion

Attraction between water molecules due to hydrogen bonding; allows surface tension and droplet formation.

Adhesion

Attraction between water molecules and other surfaces; important for capillary action

Universal Solvent

Water dissolves more substances than any other liquid because of its polarity and hydrogen bonding ability.

Van der Waals Forces

Weak attractions between nearby molecules; influence viscosity, surface tension, and phase changes in water.

Heat

Total energy (kinetic + potential) of molecular motion in a substance

Temperature

A measure of the average kinetic energy of molecules; increases as molecular motion increases.

Heat Capacity

Amount of heat required to raise the temperature of a substance by 1°C. Water’s high heat capacity stabilizes climate and temperature.

Latent Heat

Energy absorbed or released during a phase change (solid ↔ liquid ↔ gas) without a temperature change.

Latent Heat of Fusion

Energy needed to melt or freeze 1 gram of a substance. For water = 80 cal/g.

Latent Heat of Vaporization

Energy required to convert liquid water to vapour. For water = 540 cal/g at 100°C.

Evaporation

Process where individual water molecules gain enough energy to escape into the atmosphere as vapor, cooling the surface left behind.

Condensation

Conversion of water vapor back to liquid; releases latent heat and forms clouds, driving weather systems.

Global Thermostatic Effect

Earth’s oceans moderate global temperature by absorbing heat through evaporation and releasing it via condensation.

Marine Effect

The ocean’s high heat capacity causes smaller daily and seasonal temperature ranges in coastal regions compared to inland areas.

Continental Effect

Land heats and cools faster than water, resulting in greater temperature extremes in continental interiors.

Sea Breeze

Cool, moist air moving from the ocean toward land during the day as land heats faster than water.

Density of Water

Mass per unit volume (~1 g/cm³). Controlled by temperature, salinity, and pressure.

Thermal Contraction

As temperature decreases, water molecules move closer together, increasing density—except when water freezes and expands.

Ice Expansion

Water expands about 9% when frozen due to the open hexagonal structure of solid hydrogen bonds—why ice floats.

Salinity

Measure of total dissolved solids in seawater, typically 3.5% (35 ppt). It controls water density and freezing point.

Principle of Constant Proportions

The ratio of major dissolved ions (e.g., Na⁺, Cl⁻) in seawater remains nearly constant throughout the ocean, regardless of total salinity