Erosion Song EROSION

EROSION: Erosion is the transport of sediments around the earth Erosion is driven by the force of gravity.

THE AGENTS OF EROSION ARE: RUNNING WATER MOVING ICE (GLACIERS) GRAVITY (Mass Movements) WIND

What is the The primary agent of erosion? RUNNING WATER

Colorado River

Grand Canyon

Niagara Falls

Agents Erosion Each agent of erosion produces its own characteristic shape and texture in the sediment.

Erosion by water makes The rock get ROUND and SMOOTH,

EROSION BY WATER: PARTICLES ARE CARRIED IN SEVERAL WAYS DEPENDING ON THEIR SIZE

How do streams transport sediment:

SEDIMENTS that can dissolve are transported IN SOLUTION: Examples: Salt Calcite

Dissolved ions in solution Merrill Snyder

Small SEDIMENTS are transported IN SUSPENSION Examples: SILT CLAY

Merrill ES Snyder Feather Hesser

Large Sediments dragged along the bottom : Large Sediments dragged along the bottom

What determines how large a sediment a stream can erode? Merrill Snyder

What does the velocity (speed) of the stream depend upon?

VELOCITY OF A STREAM DEPENDS ON: SLOPE (gradient) AND DISCHARGE (volume of water)

Where does a stream flow the fastest on straight path Where does a stream flow the fastest on straight path? (middle, sides, top or bottom) Top View Side of Stream (Stream Bank) Top of Stream Bottom of Stream Side View The forces of friction, cohesion and drag all play a role in the streams velocity. Stream velocity is highest in the middle and top.

velocity center surface B Maximum erosion occurs where there is maximum _____________ On a straight path the maximum velocity is in the ___________ below the ____________ velocity C D center E F surface

When rivers enter a large body of water their velocity decreases and deposition occurs (depositing of sediments) How are the sediments deposited? Nissequogue enters the Long Island Sound

SEDIMENTS LEFT BEHIND BY STREAMS ARE ________ SORTED dropped off in size order

SORTING

What is the relationship between particle size and water velocity? (SEE REF. TABLE PAGE 6)

Stream Velocity The Relationship of Transported Sediments to Water Velocity: When velocity of the stream increases the size of the particle eroded increases

CALCULATE THE MINIMUM VELOCITY OF A STREAM NEEDED TO CARRY A PEBBLE (1 cm in size):

(SEE REF. TABLE PAGE 6)

What effect does erosion and deposition have on the stream? It causes the stream to go through stages THE MOVEMENT OF THE WATER CAN EVENTUALLY FORM AN OXBOW LAKE

Young Stream

Mature Stream Oxbow Lake

Old Age Stream

Comparing Young and Old Age Streams Narrow V – shaped valley Straight path Steep slopes Fast moving water Waterfalls, rapids Mature/Old Age Wide valley Many meanders Low slope Oxbow Lakes

Young Streams create V shape valleys

Old Stream

Why does a stream develop meanders?

outside of inside of (EROSION) (DEPOSITION) Water moves faster on the a bend (EROSION) DEPOSITION Water moves slower on the inside of a bend (DEPOSITION) EROSION

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

A B C D E

WHY DID RUBBER DUCKY “C” WIN THE RACE?

WHY WOULD THE WATER MOVE FASTER IN THE MIDDLE AND SLOWER NEAR THE SIDES? B C D E

WHICH RUBBER DUCKY IS GOING TO WIN? A B C D E START FINISH

A B C D E START FINISH

A B C D E START FINISH

A D E B C START FINISH

START E D A C B FINISH

START E D A C B FINISH

START E D C A B FINISH

START E D C A FINISH B

WHY DID RUBBER DUCKY “B” WIN THE RACE? START E D C FINISH A B

WHAT WOULD A CROSS SECTION (SIDE-VIEW) OF THE STREAM LOOK LIKE AT THE FINISH LINE? AERIAL VIEW (A) (B) (C) (D) CROSS-SECTION (SIDE VIEW)

What factors affect deposition rate in a river What factors affect deposition rate in a river? Characteristics of the sediment animation Size Shape Density

RATES OF DEPOSITION DEPEND ON: smaller 1. Particle size: ________ particles (clay,silt) settle more slowly than larger particles.

2. Particle shape: friction ____________ between water and the surface of particles _______ settling. As the surface area ___________ the time it takes to settle __________ The rounder the particle the faster ______ it will deposit. slows increases increases

____________ particles settle faster. 3. Particle Density: ____________ particles settle faster. denser

What is the relationship between settling rate and particle size? Complete the graphs: label each axis Settling rate Particle size Increase

What is the relationship between settling rate and shape? Particle gets flatter

What is the relationship between settling rate and density? Density increases

What is the relationship between Settling Rate and Settling Time? As the settling time increases The settling rate settling rate Inverse Relationship Settling time

Describe the size, shape and density of a particle that deposits quickly (greatest rate) A particle that is large, round and dense.

The slower the velocity of the water the ________ How does the velocity of the transporting medium ( water, wind, ice) affect deposition? The slower the velocity of the water the ________ particles will settle. It takes longer for particles to settle in ___________ water. FASTER moving

What is horizontal sorting and when does it occur? animation

Horizontal Sorting: a gradual change in the size,shape and density (of deposited particles) when a stream enters a large body of water and slows down.

Horizontal Sorting stream evaporation Ocean Ions in solution …………… boulders cobbles Roundest and densest pebbles sand evaporation Ocean Precipitation silt …………… ……………. Ions in solution (colloids) clay Smallest flattest least dense

Draw this diagram of horizontal sorting.

What is a delta and how does it form? A delta is forming where the Nissequogue River meets the Longs Island Sound.

Mississippi River Delta

Nile River Delta

Delta is a triangle shape feature that forms at the mouth of the river where sediment is deposited

What is vertical sorting? Animation

Vertical Sorting Sorting of particles from bottom to top in a layer. Occurs during flood events or when a landslide falls into a body of water Small Flat Low density Large Round Dense

What is graded bedding and when does it occur? animation Series of vertical sorting happen over and over again. Occurs when Landslides happen over and over again. Also when flooding occurs

Graded Bedding: Each layer represents a single event of deposition (3 floods)