A spit is a type of sand bar or beach that develops where a re-entrant occurs, such as at cove's headlands, by the process of longshore drift. Longshore drift (also called littoral drift) occurs due to waves meeting the beach at an oblique angle, and backwashing perpendicular to the shore, moving sediment down the beach in a zigzag pattern.
Spits are long narrow ridges of sand and shingle which project from the coastline into the sea.
During a hurricane in 1749, the Chesapeake Bay rose 15 feet (4.6 m) above normal, and a sand spit was washed up at Sewells Point. With the help of the Great Coastal Hurricane of 1806, Willoughby Spit was formed.
Over the course of the next centuries, general westward movement of sand was compounded by extensive erosion of the 7.3-mile (11.7 km) long beach of Willoughby Spit and the rest of Ocean View. Homes and businesses built too close to the water were routinely threatened by coastal storms, and recreational use was limited because of the narrow width of the beach. The City of Norfolk began implementing a "beach nourishment" construction project, which included the installation of breakwaters to reduce beach erosion and protect the shoreline. The coastline has been improved to provide more beach for recreation, and a buffer from the power of a storm-driven oceans and hurricanes.
The breakwaters are not a permanent fix and create problems of their own, because they influence the movement of sand. Beaches and coastal areas are by nature unstable. After Hurricane Isabel pounded on the coast of Norfolk in late 2003, Norfolk had to replenish the shore with 428,000 cubic yards (327,000 m3) of sand, costing the city around $3.8 million. Despite the costs of maintaining the coastline, renewed growth around the area and increased tourism have generated revenue that the region depends upon.
A SPIT
A spit or a sandspit is a deposition landform found off coasts.
The formation of a spit begins due to a change in the direction of a coastline - the main source of material building up a spit is from longshore drift which brings material from further down the coast.
Where there is a break in the coastline and a slight drop in energy, longshore drift will deposit material at a faster rate than it can be removed and gradually a ridge is built up, projecting outwards into the sea - this continues to grow by the process of longshore drift and the deposition of material.
http://oceanica.cofc.edu/An%20Educator%27sl%20Guide%20to%20Folly%20Beach/guide/driftanimation.htm
A change in prevailing wind direction often causes the end of spits to become hooked (also known as a recurved lateral).
On the spit itself, sand dunes often form and vegetation colonises.
Land is formed where the sand and shingle are finally deposited. The form of the spit is always changing, depending on weather conditions. The wind blows up sand to create dunes along the ridge of the spit.
Mud is deposited behind the growing spit which is eventually only covered with water during high tide. Plants begin to grow and thus stabilize the mud. Homes or tourist facilities are often built on sand spits. Spits have notoriously small beach areas.
Water is trapped behind the spit, creating a low energy zone, as the water begins to stagnate, mud and marshland begins to develop behind the spit;
Spits may continue to grow until deposition can no longer occur, for example due to increased depth, or the spit begins to cross the mouth of a river and the water removes the material faster than it can deposited - preventing further build up.
Longshore drift is caused by wave and current action. It is the primary method of sediment transport along the beach. The direction of this motion is always parallel to the beach face. Islands along the southeastern coast, the longshore drift most often moves in a north to south direction. This occurs because most of the wave hit the beach at an angle. In the picture below notice how the waves are approaching the beach at an angle. The yellow line represents the angle of the approaching waves. The orange arrow shows the direction of the longshore current.
What you need to do to claim this Earthcache
1. There are two different types of items in the water. What are they and why do you think they were placed there 2.Place your GPS on the sand. What is the elevation here? How could this be relevant to the development of the spit?
3. At this point what direction is the wind blowing.In your opinion is todays wind detrimental or beneficial and why?
We would love a picture of you on the steps with the sea in the background, this is not necessary to log a smiley!
DO NOT POST YOUR ANSWERS ON THE EARTHCACHE LOG PAGE!! If you do it will be deleted
Send your answers to the Adventure Stones through Geocaching.com
| I am a proud |
 |
| I am a proud |
 |