Sandspit EarthCache
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Directions to the site:
Go south on Highway 101 17.7 miles, turn right on Requa Road, follow uphill 2.3 miles to the Overlook.
At the posted coordinates you can see an excellent example of a sandspit.
A sandspit (sometimes called spit) is a deposition landform found off of coasts. At one end, the sandspits connect to land, and extends into the sea. A sandspit is a type of beach that develops where reentering occurs by the process of longshore drift.
Where the direction of the shore inland reenters, the longshore current spreads out or dissipates. No longer able to carry the full load, much of the sediment is dropped or deposited. This submerged bar of sediment allows littoral drift to continue to transport in the direction the waves are breaking, forming an above-water sandspit. Without this complementary process, the bar would not build above the surface of the waves becoming a sandspit and would instead be leveled off underwater.
Sandspits occur when longshore drift reaches a section of headland where the turn is in excess of 30 degrees. They will continue out into the sea until water pressure (i.e. a river) becomes too much to allow the sand to deposit. The sandspit may then be grown upon and become stable and often fertile. Wave refraction can occur at the end of a sandspit, carrying sediment around the end to form a hook or recurved sandspit. Wave refraction in multiple directions will cause a complex sandspit to form. Incoming waves that come in a direction other than obliquely along the sandspit will halt the growth of the sandspit, shorten it or eventually destroy it entirely.
The sediments that make up sandspits come from a variety of sources including rivers and eroding bluffs, and changes there can have a large impact on sandspits and other coastal landforms. Logging and farming upstream, for example, can increase the sediment load of rivers, which in turn, may hurt the intertidal environments around sandspits and stifle the delicate habitat. Roads or bulkheads built along bluffs, on the other hand, can drastically reduce the amount of sediment being eroded; and as a result, does not allow enough material to be pushed along to maintain the sandspit.
To log this as a find, please e-mail me the answers to the questions below. Do not post them in your log. Also, posting a picture of you or your group would be appreciated but not required.
Name the river source for this sandspit.
What shape is the sandspit?
At the parking area, the signs talk about 3 things. What are they?
Additional Hints
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