Wind and Wave erosion

1. Wind and Wave erosion Vocabulary ventifact deflation windward leeward dune saltation fetch swash backwash longshore drift sandbar spit sea stack sea arch

2. Wind and Wave erosion Erosional forces are more than just flowing water. Wind as an erosional force. Wind can carry sand in enormous volumes for long distances.

3. Wind and Wave erosion A ventifact Rock that is eroded by sediment carried by the wind is called:

4. Wind and Wave erosion Wind erosion...

5. Wind and Wave erosion Wind erosion Deflation: is the removal of top, loose, smaller layers of rock and sand exposing a harder more dense layer of “pavement” that does not erode easily.

6. Wind and Wave erosion Dunes: Mounds of sand that are deposited by wind are called “dunes”. They exist most commonly in deserts and on beaches. Windward: This is the side that receives the wind. It is a longer, gentler slope Leeward: This is the side opposite the windward side. This is a shorter,steeper slope Wind direction Leeward Windward

7. Wind and Wave erosion Dunes Different kinds Barchan Form from wind blowing over a limited amount of sand. Tips of the barchan curve point downwind Form in large sand fields. Parabolic The open end of the parabolic dune face into the wind

8. Wind and Wave erosion Moving sediment by wind is called Saltation. Sand particles lift off, bounce break and scatter. Dune Migration In areas where dunes have no natural protection (like plants) to stay in one place, the wind will move dunes. Wind carries sandup the windward side and over to the leeward or “slipface” side.

9. Wind and Wave erosion Waves The rise and fall of the water surface. As wind blows over open water it creates motion to form waves. The distance that the wind travels over open water is called fetch. Wave features: Crest wave length wave height trough

10. Wind and Wave erosion Wave features Wave period is the length of time it takes a wave to pass a certain point Wave refraction is how a wave bends as it moves and approaches a shoreline. It is caused by the front end of the wave touching bottom before the back end. This process causes wave to approach the shore at an angle. It also causes shorelines to be uneven. This is how we get “headlands” and “coves”.

11. Wind and Wave erosion Wave features Breakers Breakers are powerful agents of erosion, shaping shorelines and moving sand...

12. Wind and Wave erosion Swash and Backwash When waves strike the shore they carry sediment in two parts. 1. Swash - this is the wave part that carries the most energy and delivers sediment to the beach. The swash strikes the beach at an angle delivering the largest particles at its front to the highest point on the beach. 2. Backwash - is the gentler wash of the wave back to sea. Moving straight down, it helps sort sediment and drags some right back to the ocean. This process creates an erosional force known as “longshore drift”. This is a movement of shoreline sediment the continually reshapes beaches and 24/7/365. Longshore drift creates sandbars and spits

13. Wind and Wave erosion

14. Wind and Wave erosion As longshore drift carries sand along a shoreline, one of the formations that can occur is a sand bar. This an area where enough sand and pebble is deposited to rise above sea level. In some cases sand bars can be inhabited. But they are still temporary formations and will move...

15. Wind and Wave erosion Spit - a sand bar attached at one end to shore. The Florida Key are an example of a spit...

16. Wind and Wave erosion Shoreline features Sea Cliff - this a formation caused by wave action on a deepwater headland. Sea cliffs erode quickly and those that have a hard bedrock base leave distinct landforms...

17. Wind and Wave erosion Shoreline features When waves cut through the bedrock it can form arch ways in the rock, this is called a sea arch. When a section of land or rock is separated from shore due to wave erosion it is called a sea stack. Sea arch Sea stack (and arch)