Module 14: Deposition

delta

A triangular shaped deposit of sediments that forms where a river meets standing water.

Loess

A wind-formed deposit made of fine particles of clay and silt, deposits of finer sediment.

varves

Bands of alternating light and dark colored sediments of sand, clay, and silt that form in lakes that are covereed by ice in the winters. They are not a result of glaciers.

Flood plain

Flat land near the edges of rivers formed by mud and silt deposited by floods

glacial erratic

Giant rocks carried by a glacier are eventually dropped sometimes far from where it originated.

Sediments

Loose materials such as rock fragments, mineral grains, and bits of shell that have been moved by wind, water, ice, or gravity

sand dune migration

Once a sand dune forms, it may slowly migrate over the land. The wind moves grains of sand up the gently sloping side of the dune. This is done by saltation. When the sand grains reach the top of the dune, they slip down the steeper side. The grains are pulled by gravity. The constant movement of sand up and over the dune causes the dune to move along the ground. A dune moves in the same direction that the wind usually blows.

Sand dune formation

Sand dune formation is due to wind and gravity. It starts with an obstacle, such as a rock. The obstacle causes the wind to slow down. The wind then drops some of its sand. As more sand is deposited, the dune gets bigger. The dune becomes the obstacle that slows the wind. This causes more sand to drop. The hill takes on the typical shape of a sand dune.

stalagmites

Steep mounds or spikes of calcium carbonate that grow up from the floor of a cave, forms when groundwater deposits the calcium carbonate it is carrying and drips from the ceiling onto the floor of the cave.

longshore drift

The movement of water and sediment down a beach caused by waves coming in to shore at an angle, the direction of longshore drift is in the direction of prevailing winds

limestone caves

Water erodes the cave and it has deposits structures like stalactites and stalagmites. These caves are often exposed when the ground water level lowers.

lagoon

a body of water cut off from a larger body by a reef of sand or coral

alluvial fan

a fan-shaped mass of material deposited by a stream when the slope of the land decreases sharply, formed mostly in arid regions.

drumlin

a long, low hill of sediments deposited by a glacier. Drumlins often occur in groups called drumlin fields. The narrow end of each drumlin points in the direction the glacier was moving when it dropped the sediments.

Levee

a raised strip of sediments deposited close to the water's edge.

esker

a winding ridge of sand deposited by a stream of meltwater. Such streams flow underneath a retreating glacier

groundwater deposition

as groundwater moves through rocks it picks up ions that it later deposits.

beaches

deposits of sand and other fragments of rock left along the shoreline boundary

column

forms in a cave when a stalactite and stalagmite join together.

beaches in the winter....

have less sand because the waves have higher energy and bring the sand back offshore.

stalactites

icicle shaped features that form on cave ceilings, forms when groundwater deposits the calcium carbonate it is carrying.

dissolved load

ions dissolved in water that usually travel all the way to the ocean.

barrier islands

islands formed when waves deposit sediments to form sandbars, the first line of defense against a hurricane.

When a stream or river slows down....

it continues to carry smaller sediments but deposits larger, heavier sediments.

bed load

large sediments that are too large to move continuously and are carried by a stream along the bottom of its channel

glacial till

material dropped by a glacier ice usually in a mix of particles and rocks of all sizes. This unsorted pile is called a glacial hill.

kettle lake

occurs where a chunk of ice was left behind in the till of a retreating glacier. When the ice melted, it left a depression. The meltwater filled it to form a lake.

spit

ridge of sand that extends away from the shore. The end of the spit may hook around toward the quieter waters close to shore.

moraine

sediment deposited by a glacier. A ground moraine is a thick layer of sediments left behind by a retreating glacier. An end moraine is a low ridge of sediments deposited at the end of the glacier. It marks the greatest extent of a glacier.

suspended load

sediments carried as solids as the stream flows, the size of particles that can be carried is determined by the stream's velocity (speed).

slip face

steeply sloped side of the dune

saltation

the intermittent movement of bed load particles along a steam/river.