Exogenic Processes and Depositional Environments

Depositional environments

The combination of chemical, physical, and biological aspects that dictate what sediments, rock types and landforms are deposited or formed

Erosion

It is a geological process in which earth materials are weathered and transported

Deposition

The accumulation of weathered sediments to create different landforms

Fluvial

Depositional environment in rivers and streams

Aeolian/eolian

Depositional env. in deserts and arid areas

Alluvium

Material deposit (made up of mixture of loose rocks) of a stream

Alluvial

Mountainous environments

Glacial

Ice cap and glacial areas

Lacustrine

Lake area

Deserts

The most dominant agent of erosion in these areas is running water followed by wind

Glacial environments

The most dominant agent of erosion is ice

Glaciers

Moving ice over land

Ice sheets

Large masses of ice that cover an extensive area of land

Drainage basins

Natural springs from underground

Tidal Flat

Low-lying areas affected by tides

Deltaic

Where the river flows into the sea

Lagoonal

A small body of water closed off from a larger body of water

Deltas

Areas at the end of the mouth of a river where freshwater mixes with seawater

Wetlands

Areas that are near rivers or coastlines where soils are saturated

Marshes

Wetland where moss and soft-stemmed vegetation are most prominent

Swamps

Wetland where trees dominate the plant life

Continental shelf

Extensions of continental crust submerged by water

Atoll

Rings or partial rings of coral that usually form around a volcanic island or volcano that has receded or been eroded throughout time

Guyots/Seamounts

Elevated platforms with flat tops formed volcanic activity near the ocean floor. These can be massive and reach heights up to more than 600m

Deltas

It is formed when a river loses energy as it flows to an area of slow-moving water

Distributaries

Parts of a stream that leaves the main flow

Alluvial Fans

Formed when a stream reaches a flat area or gently sloping plain

Flood plain

A flat wide expanse of alluvium covering flat areas prone to flooding

Glacial Till

All unsorted deposits of rock formed directly by the ice

Moraines

Layers or ridges of till

Lateral Moraine

A long pile of rocky material at the edge of a glacier

Medial Moraine

A long pile of rocky material at the middle of a glacier

Esker; sand and gravel

Water that forms under a glacier through melting forms a winding ridge called ___ made of ___ and ___

Drumlins

Streamline asymmetrical hills composed of till

Kames

Steep-sided hills

Loess

Accumulated blanket of silt carried by wind in suspension and deposited over any broad areas

Sand dunes

Deposits of coarse materials in the shape of hills or ridges

Dune

Any mound or ridge of windblown sand rising to various heights up to 50m

Iron reacts with atmospheric oxygen and moisture and forms iron oxide

Provide one real-life example of oxidation

1. Water

2. Glacier

3. Wind

4. Transportation

What are the primary agents of Erosion?

Gully erosion

After heavy rain, water flows in narrow channels, eroding ravines into great depth

Carbon dioxide from the soil or atmosphere dissolves in water to form carbonic acid which reacts with minerals in rocks and may gradually dissolve the rock

Provide a real-life example of Carbonation and Solution

Water reacts with a mineral’s chemical structure which can result in the formation of clay minerals, dissolved ions, and silica in solution

Provide a real-life example of Hydrolysis

1. Daily Temperature Fluctuations: During the day, rocks are exposed to intense solar radiation and expand. At night, rapid cooling and contraction of the rock surfaces occur.

2. Differential Expansion: Different minerals within a rock expand at contract at varying rates which created internal stresses within the rock.

3. Exfoliation: Generation of mechanical stresses and the peeling of layers within the rock occurs.

Explain the full process of Thermal stress

Gravity

The driving force of mass wasting

Angle of repose

The steepest angle at which materials remain stable and do not move down slope

Translational slides

The movement of a mass of materials along a well-defined surface

Rotational slides

Occur when the descending materials move en masse along a concave, upward surface

• Removal of vegetation

• Oversteepening of slopes

• Adding moisture

Three Human Activities that may induce mass wasting

Solar energy and Gravity

What are the two driving factors of exogenic processes?