Black Sand Beach (St. Vincent) EarthCache
Hidden : 3/8/2019
Difficulty:
3 out of 5
Terrain:
2 out of 5

Size: Size: other (other)

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Geocache Description:


Black Sand Beach (St. Vincent)


Black sand
Black sand is sand that is black in color. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands, found as part of a placer deposit. Another type of black sand, found on beaches near a volcano, consists of tiny fragments of basalt. While some beaches are predominantly made of black sand, even other color beaches (e.g. gold and white) can often have deposits of black sand, particularly after storms. Larger waves can sort out sand grains leaving deposits of heavy minerals visible on the surface of erosion scarps.

There are two common ways black sand beaches can be formed:

Lava
Hot lava causes explosions when it runs into the cold water of the ocean. These explosions shatter tiny fragments of volcanic sand around. The size of these fragments can be anything from small boulders to very fine sand. It depends on the temperature of both lava and water. The color of the sand comes from a mixture of minerals (mostly iron oxides) inside the lava which darkens the sand. In this case the grains will be very sharp.

Erosion
Erosion of black volcanic rocks by rivers which cut through the rock and erode it. The black grains of sand are then carried down to the ocean, forming a beach. Erosion is like sandpaper grinding off the sharp corners of the grains. Depending on which other types of rock the rivers flow over, other minerals will be added. This results in sand colored in different colors like black, dark brown beige or green.

Logging this Earthcache
To log this earthcache, please answer the following questions and send them to me (Email or Messagecenter):
1. As described above there are two common types of black sand. Which type is the one you are standing at? Give reasons for your answer.
2. Examine the black sand. Is it coarse or fine?
3. Do you think this beach was formed by lava or by erosion? Explain why.
4. Take a stone off the ground and look at its texture. Explain it in your own words: Why do you think does the stone have this texture?
5. Optional: If you want to, you can add a picture of you at the coordinates to your log.

You can log immediately. You don't have to wait for an answer. Please send the answers in English or German.

References
Sandatlas: What is black sand?
Wikipedia: Black Sand

Additional Hints (No hints available.)



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