DEPOSITION Mr. DeMarco

Deposition: -Process by which sediments are released or dropped from an erosional system.

Deposition occurs when the velocity of the water decreases. *This occurs when the stream or river flows into a larger body of water.

Characteristics of the sediments: SIZE SHAPE DENSITY

SIZE Larger particles will settle out first. Dissolved materials may remain in solution. 1st Last

SHAPE last 1st Spherical sediments settle out first, while flatter sediments will settle out last. last 1st

Higher density sediments settle out first. last GOLD ALUMINUM

THREE TYPES OF SORTING: What is sorting?

Sorting of Sediments Vertical Sorting: the roundest, largest, and densest particles settle at the bottom of a layer, while flatter, smaller, less dense particles settle on the top (landslide, underwater landslides)

Largest Particles Medium Particles Particle Size (Calm Body of Water) Smallest Particles Small Particles Medium Particles Largest Particles

Graded Bedding: -Vertical layering, largest sediments towards bottom. -Occurs when an erosional system stops abruptly.

Graded Bedding picture:

Can be many “events” of abrupt stopping in one sample.

f05_18a_pg92 f05_18a_pg92.jpg 17

Windward side Leeward side

How can I remember which way is horizontal? HORIZONTAL SORTING How can I remember which way is horizontal? horizon

HORIZONTAL SORTING Stream enters a large body of water, the velocity decreases and deposition occurs Larger sediments are deposited first Delta may form

HORIZONTAL SORTING -Larger, more dense sediments settle out first, with a decreasing sediment size horizontally -Occurs when the velocity of the water erosional system decreases slowly (such as a stream flowing into an ocean) -Sediment size decreases in the direction the erosional system was flowing.

River Mouth – Water velocity decreases Types of Deposition Horizontal Sorting River Mouth – Water velocity decreases

Deposition will occur on the inside of a meander where the water is moving more slowly

Inside bend– deposition creates a point bar (beach-like) Outside bend- erosion creates a cut bank (steep slope)

Alluvial fans form when streams come out of mountains onto flat land – velocity slows and deposition occurs

UNSORTED GLACIAL DEPOSIT

Types of Deposition Unsorted – Associated with glacial deposits