High tide

The maximum height reached by a rising tide.

Low tide

The minimum height reached by a falling tide.

Tidal range

The difference in height between consecutive high and low waters.

Mean tide

Average tidal measurements over many years.

Tidal datum

A zero reference level based on mean low tide.

Tidal day

The time between two successive passes of the Moon over the meridian; 24 hours and 50 minutes.

Flood tide

A rising tide.

Ebb tide

A falling tide.

Slack tide

Still water during the change from rising to falling tide or vice versa.

Semi-diurnal tide

Two high tides and two low tides per day.

Diurnal tide

One high tide and one low tide per day.

Mixed tide

Unequal high and low tides during a day.

Spring tide

A tide with the greatest tidal range, occurring near new and full moons.

Neap tide

A tide with the smallest tidal range, occurring near quarter moons.

Equilibrium tides

Theoretical tides caused by gravitational forces and Earth's rotation.

Tidal forces

Forces caused by the Moon's gravity and apparent centrifugal force that produce tides.

Declination

The changing angle of the Moon and Sun relative to Earth's equator, allowing mixed or diurnal tides.

Dynamical tidal analysis

The study of tides as waves influenced by ocean conditions and Earth's rotation.

Shallow-water wave

A wave affected by the ocean floor, important in tidal behavior.

Forced wave

A wave driven by an external force.

Progressive tide

A tidal wave that travels through the ocean.

Rotary standing wave

A tidal wave pattern that rotates around an area.

Amphidromic system

A tidal system in which tides rotate around an amphidromic point.

Coriolis force

The apparent force caused by Earth's rotation that deflects moving water to the right in the Northern Hemisphere.

Standing wave

A wave pattern with areas of high and low water that remain in relatively fixed locations.

Amphidromic point

The node of a rotary tide where tidal range is approximately zero.

Co-tidal lines

Lines connecting locations with the same tidal stage around an amphidromic point.

Co-range lines

Lines connecting locations with the same tidal range around an amphidromic point.

Seiche

A standing-wave oscillation in a body of water, such as a bay or lake.

Tidal bore

A wave that travels upstream in a river or estuary as the tide rises.

Perigee

The point in the Moon's orbit when it is closest to Earth.

Weathering

All physical and chemical processes that break down or decay rocks into fragments and dissolved substances.

Mechanical weathering

Physical breakdown of rock without changing its composition.

Chemical weathering

Decomposition that changes minerals into different minerals or dissolved substances through chemical reactions.

Abrasion

Rock is worn down by rubbing or impacts from other rocks or grains carried by water, ice, or wind.

Exfoliation

Pressure release causes rocks formed deep underground to expand, crack, and peel off in layers.

Thermal expansion

Repeated heating and cooling causes rocks to expand and contract, creating stress between minerals.

Frost wedging

Water enters cracks, freezes, expands about 9%, and widens the cracks.

Salt crystal growth

Salt crystals grow in cracks and pore spaces, prying grains loose; common in arid and coastal environments.

Root wedging

Plant roots grow into rock cracks and expand them.

Oxidation

Chemical reaction between oxygen and minerals; often produces rust-like oxides.

Dissolution

Minerals dissolve into water, especially when the water is acidic.

Carbonation

Carbon dioxide dissolves in water to form carbonic acid, which can dissolve carbonate minerals such as limestone.

Hydrolysis

Water and acids break down silicate minerals such as feldspar into clay minerals and dissolved ions.

Spheroidal weathering

Chemical weathering attacks corners and edges of jointed rock blocks faster, rounding them.

Clastic particles

Rock fragments produced by mechanical weathering, ranging from boulders to clay.

Alteration products

Materials such as clay minerals and oxides produced by chemical weathering.

Soil

Loose, unconsolidated, uneroded sediment mixed with organic material.

Most resistant common mineral in the slides

Quartz is very resistant to weathering.

Minerals susceptible to chemical weathering

Feldspars and carbonates are very susceptible.

How does surface area affect weathering?

More exposed surface area allows more weathering.

How does climate affect weathering?

Warm, wet conditions generally increase chemical weathering; cold, dry conditions reduce it.

How does rainfall affect weathering?

More rainfall generally increases chemical and physical weathering and dissolution.

How does topography affect weathering?

Irregular, steep topography exposes more rock to weathering than horizontal surfaces.

Differential weathering

Different rock layers weather at different rates because their minerals differ.

Erosion

Movement or removal of loose rock particles and sediment.

Transport

Movement of sediment from its point of origin to another location.

Deposition

Sediment settles when transport slows or stops, or chemical/organic sediment accumulates.

Most important force of erosion

Gravity.

Most important agent of erosion

Water.

Gravity-transported sediment

Typically angular and unsorted, with a wide range of particle sizes.

Wind-transported sediment

Often rounded, fine-grained, and frosted by sandblasting.

Ventifacts

Rocks with sharp-edged surfaces shaped by wind-blown sand.

Water erosion features

Potholes, canyons, slot canyons, and undercut surfaces.

Glacial erosion evidence

Scratches or polished surfaces called striations; glacial deposits may be angular and unsorted.

How does transport distance affect sediment?

With longer transport, grains tend to become smaller, rounder, better sorted, and more uniform in composition.

Grain sorting

How similar sediment grains are in size.

Horizontal sorting

As water slows, larger and denser particles drop out before smaller particles.

Vertical sorting

Larger and denser grains settle first, with finer sediment settling later above them.

Compaction

Grains are packed closely together, reducing open pore space.

Cementation

Minerals precipitate from water in pore spaces or on grain surfaces, binding sediment together.

Lithification

Conversion of sediment into sedimentary rock through compaction and cementation.

Ocean salinity

Average ocean water is about 3.5% salt.

Ocean salt composition

About 90% of ocean salt is sodium chloride, according to the slides.

Residence time

Total mass of a substance dissolved in the ocean divided by its input or removal rate.

SEDIMENTARY STRUCTURES AND ENVIRONMENTS

Sediment composition

What the sediment is made of.

Sediment texture

Grain size, grain shape, and sorting.

What does grain size indicate?

Generally, larger grains indicate a higher-energy environment.

Settling velocity

For grains of the same density, larger grains settle faster than smaller grains.

Well-sorted sediment

Grains have similar sizes.

Poorly sorted sediment

Grains have a wide range of sizes.

Sedimentary structures

Features in sediment that formed before the sediment was lithified.

Bedding

Layers of horizontal sediment accumulation.

Bedding plane

The surface of deposition separating two rock layers.

Graded bedding

A layer in which grain size changes vertically, usually coarse at the bottom and finer upward.

Cross-bedding

Sloping layers formed as sediment avalanches down the lee slope of a dune or ripple.

What can cross-bed angles indicate?

The direction of current or wind flow.

Asymmetric ripples

Current ripples formed by wind or water; have a sloping stoss side and steep lee side.

Direction indicated by asymmetric ripples

The steep lee side faces downstream or downwind.

Symmetric ripples

Ripples formed by wave oscillation in shallow water, with slopes on both sides of the crest.

Mudcracks

Polygonal cracks formed when fine-grained sediment dries and contracts.

Bioturbation

Disruption of sediment layers by organisms burrowing or other biological activity.

Fossils in sedimentary rock

Preserved traces of plants or animals that can help identify past environments.

Aeolian sediment

Sediment transported or deposited by wind.

Typical dune sediment

Frosted, fine-grained, well-sorted sand with large-scale cross-bedding.

Alluvial fan

Sediment deposited where streams flow out of mountains; often coarse and poorly sorted.

Braided stream

Multiple channels formed when a sediment-clogged river splits; often steep, episodic, coarse, and poorly sorted.

Meandering river

A river that curves across relatively flat, low-gradient terrain.

Point bar

Sediment deposit on the inside of a meander bend.

Cut bank

Erosional bank on the outside of a meander bend.

Oxbow lake

A lake formed when a river cuts off a meander bend.

Meander scar

The dried-out remnant of a meander cutoff.

Delta

Sediment accumulation and shoreline protrusion where a sediment-rich river enters the ocean and slows.

Estuary

Area where fresh water and salt water mix.

Salt marsh

Grassy estuarine environment with rooted sediments and high bioturbation.

Tidal flat

Area with fine mud and sand, often poorly sorted and potentially containing shells.

Beach sediment

Sediment commonly ranging from fine to coarse sand and sometimes including boulders and shell fragments.

Barrier island

Sandy island parallel to shore, separated from the mainland by a lagoon or tidal flat.

Lagoon

Body of water behind a barrier island.

Coral reef habitat requirement

Living reefs need sunlight in shallow water within the photic zone.

Fringing reef

Reef extending outward from an island or mainland without a lagoon separating it from land.

Barrier reef

Elongate reef facing the open ocean with a lagoon behind it.

Patch reef

Small isolated, often circular or oval reef in calm, protected water behind a barrier reef.

Carbonate platform

Area where calcium carbonate accumulates, commonly in warm, shallow water.

Deep-sea ooze

Pelagic sediment or “marine snow” made from dead organisms raining down onto the seafloor.

What helps identify a sediment source?

Rock type, depositional environment, and paleocurrent direction.

COASTAL LANDFORMS AND PROCESSES

Depositional coast

Coast with abundant sediment, often wide sandy beaches and stream deltas.

Erosional coast

Coast with irregular shorelines, narrow beaches, and eroding headlands.

Headland

Rocky land that projects into the sea and is shaped by wave erosion and differential weathering.

Sea stack

Isolated rock pillar left offshore by coastal erosion.

Wave-cut terrace

Flat platform formed as waves erode a notch, cause cliff collapse, and cut into the shoreline.

Fjord

U-shaped valley carved by a glacier and later flooded by the sea.

Drowned karst

Coast formed where limestone karst terrain is weathered by dissolution and flooded by rising sea level.

Delta at the coast

Shoreline protrusion where river sediment builds outward onto the continental shelf.

Estuarine coast

Drowned river valley or embayment flooded by sea-level rise; can trap muddy sediment.

Coastal dune

Sand mound formed by wind along the coast.

Moraine

Sediment mound deposited at the edge of a glacier.

Wave-generating forces

Wind and storms, earthquakes or landslides, and the Moon/Sun.

Wave-restoring forces

Water tension and gravity; the slides also list the Coriolis effect.

Crest

Highest point of a wave.

Trough

Lowest point of a wave.

Wavelength

Distance from crest to crest or trough to trough.

Wave period

Time required for one wavelength to pass a fixed point.

Wave speed in deep water (as shown in slides)

Wavelength divided by wave period: speed = L/T.

Wave speed in shallow water (as shown in slides)

Square root of gravity multiplied by water depth: speed = √(gD).

Swash zone

Area where waves run up onto the beach.

Surf zone

Area where breaking waves roll in.

Berm

Part of the beach that slopes landward and seaward.

Nearshore bar

Underwater bedform or sand deposit offshore of the beach.

Summer/fair-weather beach

Swells move bars onshore and build a steeper berm.

Winter/storm beach

Storm waves erode sand and move it offshore into bars, flattening the beach.

Longshore transport

Sediment moves along the beach in a zigzag pattern when waves approach at an angle.

Longshore current

Shallow current flowing along the beach that transports sediment along the coast.

Spit

Alongshore extension of the coast formed as sediment continues piling up past the end of the coastline.

How can barrier islands form?

They may build from a sandbar, a cut-off spit, or flooded landward dunes/ridges.

Wave-dominated barrier islands

Long, narrow, low islands with few tidal inlets and common washover sands; examples include North Carolina and Texas.

Mixed-energy barrier islands

Shorter, wider, higher islands with numerous large inlets and a drumstick shape; example Georgia.

Jetty

Structure at a river mouth or inlet, perpendicular to shore, that helps keep a navigation passage open.

Groin

Structure built perpendicular to the beach to trap sand.

Where does sand accumulate around groins and jetties?

On the updrift side.

Seawall

Shoreline armoring built to protect landward development.

Breakwater

Offshore structure parallel to shore that reduces wave energy and encourages sediment deposition in its sheltered lee.

Shoreline armoring trade-off

Can reduce erosion locally but redirect energy, narrow beaches, and worsen erosion downdrift by reducing sediment supply.

Beach nourishment

Adding sand to a beach to replace lost sediment and widen the beach.

Overwash

Sediment carried over a beach or barrier island by waves, often during storms.