Weathering and Erosion

What is the process of Weathering and Erosion?

Physical and Chemical breakdown of rocks on the Earth's surface

Only the ___ and ___ of the rock is changed as it is eroded.

Size and shape

_____ stays the same when a rock is eroded.

Composition

Frost wedging / Ice wedging / Frost action

When ice forms in cracks, expands, and breaks up rocks.

What is Root wedging?

When trees and plants break apart rocks by pressure in their roots.

What is Abrasion?

When rocks collide and break into smaller pieces.

The longer particles undergo abrasion, the ___, ___, and ___ they become.

Smaller, rounder, smoother

Resistant to weathering = ________________

Difficult to break / wear down

When a rock layer _____ the most, it's the most resistant.

Sticks out

When a rock layer has been _____ the most, it's the least resistant.

Worn down

Chemical Weathering creates __________ (_______ changes).

New substances, composition

Chemical weathering occurs faster in __________.

Warm and wet climates

What is Carbonation?

When acidic rain seeps into the ground and dissolves certain minerals within the rock and forms huge underground caves.

What type of rocks are the most common in caves? What is its composition?

Sedimentary rocks, Limestone (They dissolve easily in acidic groundwater)

As discharge _____, velocity also _____

Increases, Increases

As slope _____, velocity also _____

Increases, Increases

Why do particles change over time as they are transported in water?

The moving water causes rocks to collide w/ each other, sharp parts break away, rock becomes smaller, smoother, and rounder.

_____ sediments are transported along the bottom of the stream.

Bigger

_____ sediments are suspended and lifted above the bottom by the water's current.

Smaller

What is a meander?

A curve in a stream

Which side of a meander will have more erosion?

Outside

Which side of a meander will have more deposition?

Inside

On a straight section of a river, where is the water velocity the fastest?

In the center of the channel, just below the surface.

Where is the deepest part of the channel (thalweg)?

Near the center of the channel.

What happens to the meanders as time goes on?

More curved

What happens to V-shaped valleys over time?

Wider and flatter

When meanders become very curved, they can form an _____.

Oxbow lake

What is a Floodplain?

An older stream that flooded a lot, and created a wide flat area adjacent to the river.

What type of streams are on steep slopes, V-shaped, have few or no meanders, and have a narrow channel?

Younger streams

What type of streams are on gentler slopes, have broad floodplains, have lots of meanders, and have a wide channel?

Older streams

Which slopes will have less meanders? (Coastal or Hillslopes)

Hillslopes (They are steep and fast)

What is a Watershed?

An area of land where surface water drains down to a single point (body of water).

What is a Delta?

Landform created when a river flows into a lake, sea, or ocean, and slows down, causing it to deposit sediments.

Deltas have the _____ discharges.

Greatest

What are Tributaries?

Smaller streams that flow into the main stream.

What are Drainage divides?

High areas of land (ridges, hills, or mountains) that separate one watershed/drainage basin from another.

The farther downstream a point is, the _____ its discharge tends to be.

Greater (More tributaries contribute water to the river)

What is Deposition?

Dropping off of sediments (Opposite of erosion)

Which part of a river do most sediments get dumped/deposited in?

Deltas (End of river and meets ocean)

Which sediments get deposited first as a stream's velocity slows down?

Larger, rounder, and denser sediments

Which sediments are carried the farthest, from the lake and eventually to the sea?

Smaller sediments

What is Horizontal sorting?

Separation of sediment sizes from upstream to downstream.

If an unsorted material was deposited/dumped all at once in still water, describe the position of sediments.

Larger sediments would go on the bottom, smaller sediments would stay at the top.

What type of sediments settle at the fastest rate in moving water?

Rounder, larger, and denser sediments

What is Gravity Erosion/Mass movement?

The downhill movement of rock and soil caused by gravity.

What are some causes of landslides?

Steep slopes, heavy rainfall, Slopes on the outside of meanders, gravity, and weak material.

List engineering structures to prevent rock slides

Terracing, Trees, Fences

How do trees prevent mass movement?

Their roots stabilize and hold the soil in place.

Describe the assortments of deposited sediments from mass movement

Unsorted and Unlayered/Angular

What can increase the likelihood of mass movement?

Adding weight on top of hills and/or removing dirt from the bottom of a hill.

Define coastal erosion

The wearing away and removal of rock, sand, and soil along a coastline by the action of waves, currents, and tides.

What can be put in place near land by the water to reduce erosion?

Boulders

What are barrier islands?

Long, narrow islands made of sand that run parallel to the coastline and are separated from the mainland by a lagoon, bay, or marsh.

How do barrier islands form?

• Waves and longshore currents move sand along the coast.

• Over time, sand accumulates into long, narrow ridges.

• These ridges become islands separated from the mainland by shallow water.

Why are barrier islands important?

• They act as a natural barrier against storms and large waves.

• They help protect the mainland from coastal erosion and flooding.

What types of sediments make up barrier islands?

Sorted sand sized particles

What are sand bars?

Small strips of sand parallel to shore line (smaller and shorter than barrier islands).

What are rip currents?

When a break in a sand bar occurs and a fast current of water flows through.

What is an inlet?

A narrow passage of water that connects a larger body of water (such as the ocean) to a bay, lagoon, or sound behind a barrier island.

What are possible benefits to newly created inlets?

Cleaner bays and increased biodiversity

What is Longshore Drift?

Main process that erodes sediment along the shore.

Waves hit the coast on an _____.

Angle

Sands are pushed in the _____ direction as the breaking waves.

Same

Sand grains ________ down the coast.

Zigzag

What are Groins?

Structures designed to prevent erosion of sand by waves.

The _____ of the deposition by the groin helps to identify the _____ of the long shore drift.

Location, Direction

What are Breakwaters?

Erosion control structure that acts like a small barrier island by reducing coastal erosion, protecting harbors and boats from rough waves, encouraging sand deposition, helping beaches grow, and reduces storm damage (storm surge & flooding) along the coast.

What are glaciers?

Huge masses of ice formed from repeated periods of snowfall that transport a tremendous amount of sediments.

What is the Milankovitch Cycle?

Over the course of tens to hundreds of years, Earth's orbits and tilt change which affect the amount of insolation that Earth receives.

What causes glaciers to "flow" slowly downhill?

Gravity

What evidence shows that glaciers drag along sediments?

Dark lines

Where are glaciers found?

At high latitudes near the poles and at any latitude with high elevation (mountains).

What is an iceberg?

Broken off chunk from a glacier that falls into the water.

What are striations?

Parallel grooves (Points in the direction of glacier).

What shape does a glacier turn a valley into?

U-shape

What shape do rivers turn a valley into?

V-shape

Why do glaciers form the shape they make in valleys?

They grind against both the floor and sides at the same time.

What is a moraine?

An unsorted and unlayered deposit left behind when a glacier starts to melt and dumps everything it was transporting. 

Unlike a delta at the end of a river, glaciers leave piles of _____ and _____ deposits.

Unsorted, Unlayered

When glaciers melt, the melt-water forms streams and deposit ______ sediments.

Sorted

Outwash plains

Flat areas in front of moraines that are sorted and layered sediments from melting water. 

What is a major difference between how sediments are organized in outwashes and moraines?

Sediments deposited in the outwash are sorted.

What are Drumlins?

Tear drop shaped hills that glaciers can leave behind besides valleys, moraines, and glacial striations.

What are Kettle lakes?

Formed when a block of ice is dropped by a glacier, it becomes surrounded by sediments, and forms a kettle-shaped lake when the ice block melts.

What are Glacial erratics?

Huge boulders that are left behind by glaciers.

How can you tell it's glacial erratic?

• The rock doesn't match the rock types in the area it's in.

• Its composition is different from the bedrock under it.

• These boulders are so immense they couldn't have been moved by any other agent of erosion.

Wind is only capable of eroding/moving _____ particles.

Sand-sized or small

What is Suspension?

When the wind picks up very small sediments and they stay in the air.

What is Sandblasting?

A form of abrasion that occurs as sediments are eroded by wind (Mushroom/pedestal rocks are common examples).

What are Sand dunes?

Deposited sand by the wind.

→ Windward side: The gentle slope facing the wind.

→ Slip face: The steeper side on the sheltered (downwind) side, where sand avalanches downward.

Sand dunes are composed of _____ sorted sand sized particles arranged in _____.

Finely, Layers

Wind blows from the _____ slope toward the _____ slope.

Gentle, Steep

What is the Cross bedded structure?

Layers of sand built on top of each other.

What implementations are used to limit erosion of sand at the beach?

Fences and Beach grass (roots anchor sediments)

A _____ environment is most important for wind erosion in sculpting the Earth's surface.

Dry

The results of wind erosion and deposition are:

Cross-bedded sand deposits containing finely sorted layers of sediment.

Climate controls the amount and type of vegetation that can grow. More vegetation generally means _____ root systems and _____ soil protection, while _____ climates often leave soil more vulnerable to erosion.

Stronger, Better, Harsh/Dry

What is Infiltration?

When water soaks into the ground.

What is an Aquifer?

A large underground reservoir of water formed by rock, sand, silt, and gravel.

What is a Water Table?

The underground boundary where the soil and rocks below are completely saturated with water.