Erosion and Deposition Part 2 Wind, Waves, Glaciers, & Mass Movement NAME: __________________________

Wind Erosion Wind has the power to pick up and move loose sediments the size of sand and smaller. Wind ERODES in two ways: Deflation and Abrasion How Wind Moves Sediment

VIDEO – Wind Erosion (click here if video does not play below)

Wind Deflation As the loose sediments are blown away, the surface of the Earth is lowered forming desert pavement, a thin, harder surface layer made of larger sediments.

Wind Abrasion Wind can only lift sand grains about 1 meter into the air, so only the bottoms of rocks are eroded away. This creates a “mushroom rock.” Because windblown sediments abrade each other they may become scratched and pitted. Wind eroded rocks are called ventifacts.

Wind Deposition  Loess  Sand Dunes • Well-sorted deposit of windblown silt. • Main sources are deserts and glacier-produced silt.  Sand Dunes • Well-sorted deposits of sand in mounds or ridges. • Characteristic Features - Side of dune with gentle slope faces into the wind. - Cross beds are the sloping layers of sand in the dune.

Major Loess Deposits in USA Cross Bedding in Sandstone These patterns in the sandstone were created by winds blowing sand around in an ancient desert much like the Sahara today.

What type of sand dune is shown in the picture above? Types of Sand Dunes What type of sand dune is shown in the picture above? __________________ DRAW an arrow on the picture showing the direction the wind is blowing.

VIDEO – DUST STORM TIME LAPSE (click here if video does not play below)

Complete the WIND SUMMARY CHART in your notes and CHECK with the teacher before you move on.

Waves (Shoreline Erosion and Deposition) Like running water, waves create relatively well-sorted deposits like sandy beaches or pebbly shorelines. Wave abrasion smooths and rounds rocks.

(The ones with a + are depositional and the rest are erosional) Take a look at the different erosional and depositional features created by waves on a shoreline. (The ones with a + are depositional and the rest are erosional)

Barrier Islands Barrier islands are also depositional features that can form from waves. Long Island Barrier Island

Shoreline Sediment Transport Longshore Drift Because waves usually strike the shore at an angle, water is pushed along the shore in one direction. This creates a longshore current. Longshore currents move material in the same direction which creates a longshore drift of sediment.

CLICK: Longshore Drift Animation :CLICK Watch longshore drift in action by clicking the link below. CLICK: Longshore Drift Animation :CLICK

Reducing the Effect of Longshore Drift To prevent erosion from longshore dirft, beach jetties or groins are installed to stop sand movement. (click the image for an animation)

VIDEO – Example of Coastal Erosion (click here if video does not play below)

Complete the WAVES SUMMARY CHART in your notes and CHECK with the teacher before you move on.

Glaciers Glacier – A large, long lasting mass of ice which forms on the land and moves because of gravity. Two types of glaciers exist: Valley (Alpine) glacier - A mountain glacier moving downhill at HIGH ELEVATIONS. Continental glacier - Large and thick, covering a landmass at HIGH LATITUDES. Glacier formation – Snow accumulates over many decades. At a depth of about 30 meters, the snow is compressed and recrystallizes into glacier ice.

Glacier Movement Glaciers flows like “Silly Putty” (plastic flow) downhill because of gravity. Valley glaciers – Move like running water in a valley; the greatest velocity is found in the center. Continental glaciers – Flow out in all directions from a central point. Glaciers can move from just a few mm/day to more than 15 m/day.

VIDEO - Glacier Movement Time Lapse (click here if video does not play below)

VIDEO - Underneath a Glacier (click here if video does not play below)

Alpine (Valley) Glacial Erosion and Landforms U – shaped valleys are eroded by glaciers!

Only two continental glaciers exist today: Greenland (10%) and Antarctica (90%).

Continental Glacier Depositional Landforms drumlin Drumlin – Long, narrow hills (tear drop shaped) – steep side faces where the glacier came from. Moraine - Sediments pushed or dragged that form unsorted piles at the edge of a glacier. Kettle or Kettle Lake - Depressions made by glacier ice chunks. Ex. Devil’s Bathtub at Mendon Ponds Park Ice Chunk

DRUMLIN BASED ON THE DRUMLIN’S SHAPE, DRAW AN ARROW BELOW SHOWING THE DIRECTION THE GLACIER MOVED THROUGH THE PICTURE.

Continental Glacier Depositional Landforms Esker - Long, narrow, snake-like hill made from a river flowing through a glacier. Kame - Circular hill of sediment deposited by running water. Outwash Plain – Wide, flat plain of sorted and layered sediment formed from glacial melt water.

View the Continental Glacial Landforms

Other Glacial Features Glaciers pick up and drag rocks along the ground. This results in erosional grooves and striations (parallel scratches ). The direction of the scratches shows the direction the glacier moved in. Erratic - Large “out-of-place” boulder carried by a glacier and deposited hundreds of miles from where it formed. Often doesn’t match the underlying bedrock.

Glacial Sediment Glacial till is unsorted and unlayered sediment deposited directly by a glacier. When a glacier melts, the different sizes and compositions of sediment are deposited together. Glacial till often shows the affects of abrasion: rounded and scratched

VIDEO - A Glacier Melting and Depositing Sediment (click here if video does not play below) Look at the dark sediment carried in and on the glacier!

The Finger Lakes in NYS are U-shaped valleys eroded by glaciers that have filled with water.

Complete the GLACIER SUMMARY CHART in your notes and CHECK with the teacher before you move on.

Gravity or Mass Movement Any time gravity acts on its own to pull rocks or sediment downhill is considered mass movement. Rock slides, landslides, avalanches, mudslides, and debris flows are all types of mass movement erosion. Mass movement sediments are angular and dumped together in a random deposit that is unsorted and unlayered.

VIDEO - Mass Movement in Action (click here if the video below does not play)

Examples of Mass Movement

Human Erosion Human activities such as construction, road building, mining, deforestation, and poor farming practices can also contribute to erosion.

Complete the GRAVITY SUMMARY CHART in your notes and CHECK with the teacher.