EROSION: The force that shapes the Earth! Erosion: What is it? Erosion: The MOVEMENT of SEDIMENTS by natural FORCES Agents of Erosion: Forces that move sediments There are SEVERAL AGENTS of erosion… EROSION: The force that shapes the Earth!

AGENT 1: Erosion by Gravity CREEP…Gravity pulls the soil down slope… Very… Very… Very… Slowly Creep causes… (see diagram) EROSION: The force that shapes the Earth!

Agent 1: Erosion by Gravity Slump Don’t build your house on a steep slope! Landslide These are both caused by gravity! EROSION: The force that shapes the Earth!

Agent 1: Erosion by Gravity Rock Fall: LARGE sediments fall or slide off a mountain All gravity erosion is also called MASS MOVEMENT! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. What is erosion? How is it different than weathering? 2. Natural forces that move sediments are called what? 3. All forms of gravity erosion are called what? EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Agent 2: Erosion By Wind Small sediments (like sand) get blown around! Large sediments (like cobbles and boulders) get left behind! Large sediments get “sandblasted” They look pitted and frosted… EROSION: The force that shapes the Earth!

Agents 2: Erosion By Wind A beautiful ARCH formed by WIND EROSION blew sand against the bedrock and wore it away EROSION: The force that shapes the Earth!

Agents 2: Erosion By Wind SAND DUNES form by wind erosion! Which way does the wind blow? EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. How is wind an agent of erosion? 2. Compared to gravity, the size of the sediments eroded by wind are MUCH ____ 3. Why is wind a major erosion agent in dry areas? EROSION: The force that shapes the Earth!

Agent 3:Erosion By Waves Terraces Cliffs Waves crash on the shore and break apart the bedrock EROSION: The force that shapes the Earth!

Agent 3:Erosion By Waves Arch Waves wrap around the front and break apart the bedrock EROSION: The force that shapes the Earth!

Agent 3: Erosion By Waves Stack Most of the rock from the arch has completely eroded EROSION: The force that shapes the Earth!

Agent 3: Erosion By Waves Waves bend parallel to the shore and take sand with them! This is called long shore current The “groin” was built to stop beach erosion!! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. Why are waves agents of erosion? 2. Which agent can erode larger sediments, wind or waves? 3. Which agent can move larger sediments, waves or gravity? EROSION: The force that shapes the Earth!

Agent 4: Erosion by Glaciers A GLACIER is a large MASS of MOVING ICE GLACIERS can be found in two places… HIGH ALTITUDES… ALPINE glaciers HIGH LATITUDES… CONTINENTAL glaciers EROSION: The force that shapes the Earth!

Agent 4: Erosion by Alpine Glaciers Flowing ice picks up Sediment and rocks... ...And carries them along Scraping the bedrock along the way! An excellent way to cause ________ EROSION! EROSION: The force that shapes the Earth!

Features left by Alpine Glaciers Glaciers erode valleys into a “U” shape EROSION: The force that shapes the Earth!

Features left by Alpine Glaciers The landscape left behind by alpine glaciers! U-shaped Valleys EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. Where are alpine glaciers found? 2. Ridge caused by glacial erosion: 3. Sharp peak left at top of mountain: 4. Shape of valley left by glacier: EROSION: The force that shapes the Earth!

Agent 4:Continental Glaciers 2.0x106 to 1x104years ago Four periods of continental glaciers growing and melting Only found at high latitudes now! Each ice advance lasted for 40,000 to 200,000 years Warm spells lasted 10,000 to 30,000 years Are we living in a warm period now between ice ages? EROSION: The force that shapes the Earth!

Continental Glaciers and Landscapes Sheets of ice advance... And then melt back... Leaving behind a very cool landscape! Pittsford area is LOADED with these features! EROSION: The force that shapes the Earth!

Features of Continental Glaciers Striations are scratch marks made as ice drags rocks across bedrock They show the glacier’s direction of motion EROSION: The force that shapes the Earth!

Features of Continental Glaciers Glaciers carved valleys and melted… Fill the valley with water! Finger Lakes! Show the glacier’s direction motion when it melted! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. Most soil in Western NY was deposited by glaciers. Is it transported or residual? 2. A boulder with scratches on it was most likely transported here by what agent of erosion? 3. Finger lakes and striations show that the last glaciers in North America moved in what direction? EROSION: The force that shapes the Earth!

DEPOSITION: The Opposite of EROSION EVERY EROSIONAL AGENT must DROP the sediments it erodes! Deposition: When sediments are deposited Deposition and Erosion always happen together! EROSION: The force that shapes the Earth!

DEPOSITION: SORTED or UNSORTED Deposit of all different shape and size sediments is called UNSORTED Deposit arranged by SIZE or SHAPE is called SORTED sediments SORTED UNSORTED EROSION: The force that shapes the Earth!

Deposition by Glaciers The Glacier melts.... Sediments are deposited at the melting edge… And piled up! The PILE is called a Moraine EROSION: The force that shapes the Earth!

Deposition by Glaciers BIG PILE of SEDIMENTS Left by a GLACIER Sediments are UNSORTED… Moraines are formed by both glacier types EROSION: The force that shapes the Earth!

Deposition by Glaciers A HUGE boulder left by a GLACIER What’s this granite boulder doing here? It’s an________ ERRATIC EROSION: The force that shapes the Earth!

Deposition by Glaciers This long narrow hill left by a glacier is called an ___________ ESKER EROSION: The force that shapes the Earth!

Deposition by Glaciers This canoe shaped hill left by a glacier. It’s called a ________ DRUMLIN EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. How do glaciers cause deposition? 2. Are glacier deposits sorted or unsorted? 3. Large boulder left behind by glaciers… 4. Funny-shaped hills left behind by glaciers (3 types). Are these made of sorted sediments? EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Deposition by WIND PILES of sand left behind from WIND EROSION are called ______ DUNES Dunes are SORTED sediments…sizes are sorted out! EROSION: The force that shapes the Earth!

Deposition by WAVES Sediments left behind from WAVE EROSION are called a __________ BEACH WAVE deposits are SORTED EROSION: The force that shapes the Earth!

GRAVITY sediments are UNSORTED because they are all mixed up! Deposition by GRAVITY PILES of sediments left behind from at the bottom of a slope from GRAVITY EROSION GRAVITY sediments are UNSORTED because they are all mixed up! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Summary 1. What is DEPOSITION? 2. Deposition from glaciers and gravity tend to be sorted or unsorted? Explain? 3. Deposition from wind and waves tends to be sorted or unsorted? Explain? EROSION: The force that shapes the Earth!

Agent 5:STREAMS A SYSTEM of Erosion and Deposition Streams are the MAJOR AGENT of erosion on Earth! Streams cause erosion by moving sediments when water velocity is high! Streams cause deposition when they leave those sediments behind when the water velocity decreases! Streams are erosional-depositional systems! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Erosion by Streams Streams are moving water. As they flow the water cuts down through the bedrock Stream Valleys are cut into a “V” shaped EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Erosion by Streams DOWNCUTTING… The stream erodes down through the soil and rock… Makes the channel deeper EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Erosion by Streams Streams also erode the banks of their channels Erosion and deposition happen in different places… To the other The stream channel moves from one side EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Erosion by Streams Erosion happens on outside of curve… Deposition happens on the inside of curve… Stream velocity is higher there! Stream velocity is lower there! The curves are called meanders! EROSION: The force that shapes the Earth!

EROSION: The force that shapes the Earth! Erosion by Streams These meanders have been cut down through hundreds of meters of bedrock! EROSION: The force that shapes the Earth!

Erosion by Streams Don’t build your house on the outside of a meander! The water velocity is HIGH THERE and will cause erosion! EROSION: The force that shapes the Earth!

Deposition by Streams When the stream floods it deposits sediments on either side! This wide, flat area is a floodplain! It has AWESOME soil! EROSION: The force that shapes the Earth!

Deposition by Streams Don’t build your house on a floodplain! Floodplain deposits are sorted! EROSION: The force that shapes the Earth!

This is called a _________ Deposition by Streams Stream enters the ocean … Its velocity decreases And it deposits the sediments it was transporting This is called a _________ delta EROSION: The force that shapes the Earth!

Deposition by Streams Delta deposits are definitely sorted! Deltas make really fertile soil! Would you build your house on a delta? EROSION: The force that shapes the Earth!

Sediments Deposited by Streams Rounded and Sorted These stream sediments are sorted by size Deposits are sorted because larger sediments settle first! How Streams Work

Horizontal Sorting: Large sediments deposited first (near shore) followed by small sediments Stream enters ocean, velocity decreases Ocean Larger sediments deposited first near mouth Small sediments deposited last away from shore This is how DELTAS form! How Streams Work

EROSION: The force that shapes the Earth! Summary 1. Streams cause erosion by downcutting. Explain… 2. Streams erode the outside of meanders. Why? 3. Deposition happens at the inside of meanders. Why? 4. Sediments deposited by streams tend to be sorted or unsorted? 5. What shape valley do streams make? EROSION: The force that shapes the Earth!

Deposition by Continental Glaciers Ice Tunnel inside the glacier…Are these sediments sorted or unsorted? EROSION: The force that shapes the Earth!

FEATURES left by Alpine Glaciers Alpine glacier fills a mountain valley Break and move rocks and sediments Sediments are left behind And a CIRQUE formed! EROSION: The force that shapes the Earth!

Features left by Alpine Glaciers Alpine glaciers form in mountain valleys Glaciers melt away and leave behind cirques An Arête is left between them A HORN is left at the top EROSION: The force that shapes the Earth!