Depositional Coast

A coastline characterized by wide sandy beaches, stream deltas, and an overabundance of sediment.

Erosional Coast

A coastline characterized by an irregular shape, narrow beaches, and eroding headlands.

Wave-Cut Terrace

A flat platform formed by wave erosion when waves erode a notch in a cliff causing it to collapse undercutting.

Fjord

A drowned U-shaped valley carved by glaciers and flooded by rising sea levels.

Drowned Karst

Limestone topography formed by chemical weathering and dissolution, which has been flooded by sea-level rise.

Delta

A shoreline protuberance where a river meets the ocean and sediment builds out onto the continental shelf.

Estuary (Drowned River Valley)

An embayment created when a river valley is flooded by sea level rise, trapping muddy sediments.

Spit

An alongshore extension of a coast formed by sand piling up where the coastline ends.

Barrier Island

A sandy, shore-parallel island separated from the mainland coast by a lagoon or tidal flat.

Jetties

Structures built perpendicular to the shoreline at rivers or inlets to keep navigation passages open.

Groins

Structures built perpendicular to a beach to trap sand, causing sediment to accumulate on the updrift side.

Seawalls

Structures built for shoreline armoring to protect landward development from coastal erosion.

Breakwaters

Structures built offshore, parallel to the shore, to protect the beach from waves and encourage sediment deposition behind them.

Atoll

A ring-shaped coral reef system surrounding a lagoon, formed as a volcanic island subsides and erodes below sea level.

Sediment Sorting

A measure of how similar grain sizes are within a sediment or rock, reflecting changes in system energy.

Graded Bedding

A layer of sediment where grain size changes vertically, being coarser at the bottom and progressively finer toward the top.

Cross-Bedding

Inclined layers of sediment formed as sand avalanches down the lee slope of dunes or ripples, indicating flow direction.

Symmetric Ripples (Wave-Oscillation Ripples)

Ripples formed by oscillatory wave motion in shallow water, featuring sharp crests and equal slopes on both sides.

Asymmetric Ripples (Current Ripples)

Ripples formed by unidirectional wind or water currents, featuring a gentle stoss slope and a steep lee slope.

Mudcracks

Polygonal patterns of cracks formed in very fine-grained sediment as it dries and contracts.

Bioturbation

The disturbance of sediment layers by biological activity, such as animals or plants burrowing.

Alluvial Fan

A fan-shaped deposit of poorly sorted, coarse sediment flowing out of mountains via high-energy floods or mudflows.

Point Bar

An area of sediment deposition on the inside bend of a meandering river.

Cutbank

An erosional bank located along the outside of a meandering river bend.

Oxbow Lake

A U-shaped body of water formed when a meandering river takes a shortcut and cuts off a tight bend.

Sediment Roundness

A measure of how sharp or smooth the corners and edges of a sediment grain are, with higher roundness indicating a longer transport distance.

Sediment Sphericity

A measure of how closely a sediment particle approaches the geometric shape of a sphere.

Sediment Maturity

A measure of sediment transport and weathering progress, characterized by stable minerals like quartz, well-rounded grains, and high sorting.

Beach Slope Dynamics

The relationship where coarser sediment grains create steeper beach slopes due to high water infiltration, while finer grains result in flatter slopes due to increased backwash.

Phaneritic Igneous Texture

An igneous rock texture characterized by large, mineral crystals that are easily visible to the naked eye, formed by slow cooling beneath Earth's surface.