Sediment Transport and Deposition Quiz

Sediment Transport and Deposition

• Sediment is moved by water, wind, ice, and mass wasting.
• Water transports sediment along shorelines through waves and currents.
• Wind carries sediment, as seen in dust storms.
• Ice transports sediment, as seen in glaciers.
• Mass wasting involves gravity-driven movement of rock and sediment.

The Navajo Sandstone

• A large exposure of pink and white Navajo Sandstone is located in Zion National Park.
• The Wave, a Navajo sandstone formation, is in Arizona.

Transport and Deposition of Sediment (Environments)

• Deposition is the laying down of sediment on land and in the ocean.
• Environments such as braided meltwater streams, alluvial fans, glacial environments, playa lakes, and eolian environments, among others, all have unique depositional processes and sediment types.
• Sedimentary facies reflect the environment.
• Examples of environments include: lakes, streams, estuaries, shallow marine environments, the continental shelf, continental slope, submarine valleys, deep marine environments, and many others.

Different Environments and Sediment Types

• Different environments on Earth have unique sediment types associated with them.
• Sediments can be gravelly, sandy, or gravelly-sandy alluvial.
• Estuaries and beaches are some environments with distinctive sediment types.

Depositional Environments on Land

• Four principal sites for deposition on land are margins of glaciers, in streams, in lakes, and places where wind blows strongly.

Alluvial Fan

• Alluvial fans are landform features which form when a stream or river flows from a mountainous terrain into a flatter area.
• The deposit tends to have a fan-shape.

River Systems

• River systems include terraces (from abandoned floodplains), main channel flows, floodplains, and natural levees.

River Valley Types

• Valley shapes vary, from V-shaped valleys in young valleys (rapid erosion), to wider, meandering forms in mature valleys (slower erosion).
• Characteristics like the presence of levees and oxbow lakes can characterize valleys.

Braided Streams

• Braided streams exhibit multiple channels that are separated by gravel bars and other sediment deposits. Water flow is turbulent and the channels move and change shape.

Meandering Rivers

• Meandering rivers exhibit a winding, sinuous pattern. Point bars form on the inside bends of the curves. Channels erode on the outside bends.

Floodplains

• Floodplains are flat areas beside a river that become flooded during high flows. Natural levees are formed by sediment deposition during flooding events.

Glacial Environments

• These environments deposit sediment in locations with ice sheets or glaciers.

Playas or Dry Lakebeds

• Sediment is deposited in areas that frequently dry up, such as dry lakebeds.

Sand Dunes

• Sand dunes form in areas with strong and intermittent wind conditions.

Eolian Environments and Loess

• Eolian environments feature wind-blown sediment deposits, often called Loess.
• Loess is a type of wind-blown silt.

Coastal Deposits

• Coastal environments (swamps, estuaries, barrier islands, lagoons, reefs, and deltas) display various sediment types.

Depositional Environments Near the Ocean

• Sediment is commonly deposited around the edges of the ocean, in areas where current velocity decreases. Estuaries are semi-enclosed water bodies where fresh and saltwater mix.

Deltas

• Deltas are fan-shaped deposits formed where a stream enters a standing body of water.

Beaches

• Beaches predominantly consist of quartz, a common component of beach sand.

Barrier Islands

• Barrier islands are flat areas of sand parallel to the mainland coast. They're part of dune systems.

Tidal Flats

• Tidal flats are areas experiencing shallow, alternately wet and dry conditions.

Lagoons

• Lagoons are sheltered, calm bodies of water near the coast protected from high waves and currents.

Reefs

• Reefs are structures of coral, shell debris and other biogenic calcium carbonate sediment.

Atolls

• Atolls are ring-shaped coral reefs formed around sinking volcanic islands, creating a lagoon.

Limestone

• Limestone is a rock primarily composed of calcium carbonate. Often found in coastal, ocean, and reef environments. Often represents old or ancient reefs.

Deep Ocean Environments

• Deep ocean features such as continental slopes, abyssal plains, and turbidity currents are discussed. Turbidity currents are fast moving mixtures of water and sediment that occur in the continental slope/shelf. Submarine canyons can be present.

Plate Boundaries: Divergent

• Rift valleys are linear valleys along divergent plate boundaries or spreading centers, often resulting from tectonic activity.

Plate Boundaries: Convergent

• Structural basins collect sediment along mountain ranges formed by continental collisions.

Plate Boundaries: Convergent Features

• Accretionary wedges develop from sediment carried to trenches by subducting plates. Ophiolites are a specific type of geological formation.