Transcript Sediment Sorting - davis.k12.ut.us

Erosion at work
SEDIMENT SORTING
EROSION
Erosion is the process of moving sediment from
one location to another.
 The most important force of erosion is gravity.
 The most important agent of erosion is water.

AGENTS OF EROSION - WATER
Running Water – sediments that have been transported through
running water appear rounded and smooth and are deposited in
sorted piles.
Sorting
Boulders
Cobbles
Gravel
Sand
Silt
Clay
AGENTS OF EROSION - WATER



Suspension - the moving water picks up small, less
dense particles and carries them along.
Saltation - particles with medium size and density
bounce along the river bottom.
Rolling - the water can help particles with large size
and density roll along the bottom of the river.
AGENTS OF EROSION - WATER
Water
erodes
sediment
on the
outside
curves
and
deposits
(drops)
sediment
on the
inside
curves.
NIAGARA FALLS
AGENTS OF EROSION - ICE
Glaciers – sediments that have been transported by glaciers
appear scratched and grooved. They are deposited in completely
unsorted piles, because they were dropped during melting. Large
boulders can only be transported by glaciers.
AGENTS OF EROSION – ICE/WATER
U-shaped valleys are made by a glacier.
 V-shaped valleys are made by running water.

AGENTS OF EROSION - WATER
Waves - move in the ocean and
pick up rocks. The rocks rub
together eventually making
sand. If the waves hit land, the
water can tear away at the land
because it is carrying the rock
particles.
AGENTS OF EROSION- WIND
Wind - sediments transported by wind are deposited in sorted piles.
Only very small particles can usually be transported by the wind.
Wind erosion is dirt and other particles that are blown around
eventually reshaping the land.
FORCE OF EROSION
Gravity – sediments that are transported by gravity are found in
piles at the bottom of cliffs or steep slopes. They appear angular
(jagged) and unsorted.
Erosion leads to…
DEPOSITION
WHAT IS DEPOSITION?
●Keyword = Drop-off or deposit
●The dropping off (depositing) of rock particles and
earth materials (also called sedimentation)
FACTORS THAT AFFECT DEPOSITION
●Particle Size
●Particle Density
●Particle Shape
●Settling Rate & Settling Time
PARTICLE SIZE
●Large particles: settle quickly
●Small particles: settle slowly
●Tiny particles: only settle out when water is saturated
(can’t hold any more of it) or evaporates
IN WHAT ORDER WILL THESE
PARTICLES SETTLE?
A
B
C
C
D
B
D
PARTICLE DENSITY
● If particles have the same shape and size...
…the denser particles will settle more quickly.
PARTICLE SHAPE
● Depends upon friction (interaction) between water
and particle surface
Flat, irregular
particles
Small, rounded
particles
More surface area Less surface area
Settle more
slowly
Settle more
quickly
HOW ARE PARTICLES SORTED?
● When particles are dropped off, they get sorted
(arranged) in a certain way.
● There are 2 types of sorting:
1. Horizontal Sorting
2. Vertical
Sorting
HORIZONTAL SORTING BY DENSITY AND SIZE

Rivers, streams, and oceans carry sediments
and deposit them on the basis of density and
size and shape.
•
•
•
Large, round, densest sediments deposit first
Small, flat, less dense sediments second
With evaporation, suspended sediment falls
VERTICAL SORTING
●Usually found underwater
●Sorting goes from bottom to top:
Largest to Smallest
●Graded layers can be created,
indicating distinct depositional
events
3rd layer
2nd layer
1st layer
SPECIFIC SORTING
●Streams: Sometimes when
a stream enters a lake,
deposits are fanned out in a
triangular shape (delta)
●Glaciers: large rocks moved
without being broken into
smaller pieces – rocks are
dropped at the edge as a
glacier melts
SORTING DATA CHART

Look at each picture and describe what type of
sediments are present and how the sediments settled
out. Fill in the chart with your data.
#
1
2
3
4
5
6
7
8
9
10
11
12
Type of sediments
How or why it settled:
PICTURE #1
PICTURE #2
PICTURE #3
PICTURE #4
PICTURE #5
PICTURE #6
PICTURE #7
PICTURE #8
PICTURE #9