Mass Movements, Wind and Glaciers -presents- NC Competency Goal 4: The learner will build an understanding of the hydrosphere and its interactions and influences on the lithosphere, the atmosphere, and environmental quality.

NC Competency Goal 4 Mass Movements at Earth’s Surface Gravity pulls loose sediment and weathered material down steep slopes and even small hills. This process Is called mass movement. Weathering Mass Movements gravity Video of Weathering (click on the screen) Weathering is the process by which materials are broken down into smaller pieces. In smaller pieces, matter is lighter and easier to move.

NC Competency Goal 4 All mass movements occur on slopes. Mass movements can be extremely slow….or very rapid (and unexpected)! Variables that influence Mass Movements Materials weight Friction Earth “shakers” Mass Movements at Earth’s Surface

NC Competency Goal 4 Common Types of Mass Movements 1- Slide Slide is a term that describes the movement of a “block” of Earth. Slides occur on land that is sloped. Slides come in many forms such as: Landslides Mudslides Avalanches Mass Movements at Earth’s Surface gravity

NC Competency Goal 4 A landslide occurs when a block of loose soil, rock, and debris separates from the underlying bedrock. Mass Movements at Earth’s Surface 1- Slide Common Types of Mass Movements

NC Competency Goal 4 In some landslides, the material breaks apart and slides down as one block…with little interest in mixing with other materials. Common Types of Mass Movements Slide (continued)

NC Competency Goal 4 Common Types of Mass Movements Water plays a key role in “mass movements”……. Water can hold soils together…..but too much water can get between grains of sediment and reduce friction. This may produce a landslide or “mudflow”. In other cases, a reduction in friction is needed for massive blocks of Earth to move.

NC Competency Goal 4 Common Types of Mass Movements 2- Flow …movement that involves mixing of particles within a moving mass Mass Movements at Earth’s Surface

NC Competency Goal 4 Flows can move extremely fast or very slow. Example: Mudflows (mixtures of mud and water) Mass Movements at Earth’s Surface Common Types of Mass Movements Flow (continued) Video of Mudflows Click on the link above to see a short video on mudflows.

NC Competency Goal 4 Mass Movements at Earth’s Surface Common Types of Mass Movements Flow (continued) Click here to watch a movie on mudslides on the USGS Website ( approximately 1 hr). Title: Riding the Storm

NC Competency Goal 4 Mudflows can be triggered by an earthquake or volcanic activity. They often occur where there is little vegetation. The eruption of Mt. St. Helens in 1980 triggered mudflows that traveled as fast as 30 km/h. Mass Movements at Earth’s Surface Flow (continued) Common Types of Mass Movements Video of Mt. St. Helens

NC Competency Goal 4 3 – Rock Falls Usually occur at high elevations on high cliffs. Rock falls are less likely to occur in humid regions, where the rock is typically covered by a thick layer of soil, vegetation, and loose materials. Mass Movements at Earth’s Surface Common Types of Mass Movements

NC Competency Goal 4 Common Types of Mass Movements 3 – Rock Falls Fall is a term that describes the “free fall” of Earth’s materials due to gravity. Mass Movements at Earth’s Surface

NC Competency Goal 4 4- Creep Similar to landslides, but much slower. The creep is the slow steady flow of soils and weathered particles downhill. 1 Mass Movements at Earth’s Surface Common Types of Mass Movements

NC Competency Goal Common Types of Mass Movements Mass Movements at Earth’s Surface Creep (continued) -Loose materials on almost all slopes undergo creep.

NC Competency Goal Slumps A slump occurs when Earth Materials in a landslide rotate and slide along a curved surface. Mass Movements at Earth’s Surface Common Types of Mass Movements

NC Competency Goal Avalanche Avalanches occur in areas where there are mountains and thick accumulations of snow. About 10,000 avalanches occur each year just in the western United States. Mass Movements at Earth’s Surface Common Types of Mass Movements

NC Competency Goal 4 Avalanche (continued)… Common Types of Mass Movements

NC Competency Goal 4 Avalanche (continued)… Common Types of Mass Movements Melted ice Freezes and provides less friction

NC Competency Goal 4 How Mass Movements Affect People Mass movements are natural processes, however, humans contribute to mass movements by: Constructing Heavy Buildings Making roads on steep slopes Poor maintenance of septic systems which can leak and trigger slides. Mass Movements at Earth’s Surface

NC Competency Goal 4 Q: Identify and describe one type of rapid mass movement and one type of slow mass movement. Answer: A rapid movement is a landslide, which occurs when Earth material moves rapidly downslope. A slow movement is creep. Creep occurs when very fine sediment becomes filled with water and slowly moves downslope. Mass Movements at Earth’s Surface Assignment:

NC Competency Goal 4 Q: Describe the underlying force behind all forms of mass movement and explain its role in the process of mass movement. Answer: Gravity is the underlying force behind ALL mass movements and pulls all material to the lowest level on Earth’s surface. Mass Movements at Earth’s Surface Assignment:

NC Competency Goal 4 Q: How does water affect the process of mass movement. Answer: Water contributes to mass movement by adding weight and filling the spaces between sediment particles, thereby allowing the particles to more easily slide over one another as they slide downslope. Mass Movements at Earth’s Surface Assignment:

NC Competency Goal 4 Q: What precautions can humans take to avoid the dangers associated with mass movements? Answer: If you’re going to build a structure in an area where there are known mass movements, build that structure so that it can withstand the changing landscape. Mass Movements at Earth’s Surface Assignment:

NC Competency Goal 4 Question: Can you think of one MAJOR difference between wind erosion and water erosion? Answer: Unlike water, wind can carry sediments uphill as well as downhill. Wind

NC Competency Goal 4 Winds transport materials by causing their particles to move in different ways: 1 – Wind can cause sand particles to move in a rolling motion. Strong winds can cause these particles to stay airborne for long distances. This method of wind transport is called suspension. Wind Erosion And Transport

NC Competency Goal 4 Most areas where wind transport occurs experience very little precipitation. Deserts Arid Areas Seashores Some lakeshores Wind Erosion And Transport

NC Competency Goal 4 The lowering of land surface that results from wind’s removal of surface particles is called deflation. Wind Sediment After the wind stops, a coarse surface is left behind. This is called desert pavement. Wind Erosion And Transport (photo of desert pavement)

NC Competency Goal 4 Wind Erosion And Transport U.S. Map of Wind Erosion Whiteville, NC Wind Erosion Areas

NC Competency Goal 4 Another form of wind erosion is called abrasion. “Abrasion is basically natures sandblaster”! Wind Erosion And Transport The picture above shows a conglomerate rock called the Baja Mushroom, located in Mexico. Wind abrasion carved this rock!

NC Competency Goal 4 Windblown sand particles can form pits and grooves in rocks. Continual wind abrasion produces a polished smooth stone. Wind Erosion And Transport Rocks shaped by windblown abrasion are called ventifacts.

NC Competency Goal 4 Wind Deposition Wind speed slows down Sand As wind speed slows down, sand and other materials carried by the wind can no longer stay in the air. They soon drop from the air to form a deposit on the ground! … and this is how many dunes are formed! 12 – 25 m

NC Competency Goal 4 Types of Dunes 1-Barchan 2-Transverse 3-Parabolic 4-Longitudinal

NC Competency Goal 4 Types of Dunes Type Shape Size Area of formation Barchan Crescent 30m high Flat areas where there is little sand or vegetation.

NC Competency Goal 4 Types of Dunes Type Shape Size Area of formation Transverse long ridges 25m high Areas of Plentiful sand but little to no vegetation. (Transverse Dunes also form perpendicular to the wind).

NC Competency Goal 4 Types of Dunes Type Shape Size Area of formation Parabolic Sharp Curves 30m high Form between clumps of plants. Common on seacoast.

NC Competency Goal 4 Types of Dunes Type Shape Size Area of formation Longitudinal Tall Ridges 90m high Areas of limited sand but lots of wind. (parallel to wind direction).

NC Competency Goal 4 Assignment Question: What is so important about sand dunes and why should we care about them anyway?

NC Competency Goal 4 Assignment Answer: Dunes provide a home for many shoreline creatures and protect homes and coastal areas from rapid erosion.

NC Competency Goal 4 Dune Migration Migrating dunes can block highways and cover farmland.

NC Competency Goal 4 Glaciers A large moving mass of ice is called a glacier. Glaciers erode, transport, and deposit huge amounts of rocks and sediment.

NC Competency Goal 4 Glaciers Glaciers cover about 10% of the Earth and are found around Greenland and Antarctica. These areas stay cold year round so the snow doesn’t completely melt. The snow accumulates in an area called a snowfield.

NC Competency Goal 4 Glaciers Eventually, a glacier will form from a snowfield.

NC Competency Goal 4 Glaciers 2 Types of Glaciers 1 – Valley Glacier The sides and bottom of a valley glacier are in contact with the ground. Because of friction with the ground, the sides and bottom will move slower than the middle. Typically, valley glaciers are slow and move only a few millimeters a day.

NC Competency Goal 4 Glaciers 2 Types of Glaciers 2 – Continental Glacier Cover broad “continent-sized” areas. They form the same way as valley glaciers… but move differently. Continental glaciers are the thickest in the center. The weight of the center causes the glacier to flatten out in all directions. Continental glaciers are also called ice sheets.

NC Competency Goal 4 Glacial Erosion

NC Competency Goal 4 Glacial Erosion Cirque – deep depression carved out by valley glaciers. Arete – sharp steep ridge formed by the meeting of two cirques. Horn – steep ridge formed at the mountain TOP by glaciers on three or four sides of a mountain.

Glacial Deposition Glacial Till – mixed debris that glaciers carry. NC Competency Goal 4 When a glacier melts, glacial till is left behind. Mountain ridges consisting of till deposited by glaciers are called moraines.

Glacial Deposition NC Competency Goal 4 Sometimes a large block of a glacier breaks off…..and forms a depression in the ground. This depression is called a “kettle”. In time, the kettle will fill with precipitation and form a kettle lake.