GC41XZN Black Beach (Earthcache) in Islas Canarias, Spain created by Bitola

GC41XZN ▼

A cache by Bitola Message this owner

Hidden : 12/31/2012

Difficulty:

Terrain:

Size: Size: other (other)

Join now to view geocache location details. It's free!

Watch

How Geocaching Works

Please note Use of geocaching.com services is subject to the terms and conditions in our disclaimer.

Geocache Description:

There are more than 100 different beaches on the third largest island of the Canary Islands, Gran Canaria.

Along the 236km of coastline you will find sandy beaches, pebble beaches and rocky surfaces....
But on the total of 60 kilometers of beaches there's a beach, we want to show you and bring it closer to you.

Black sand beach

There are two types of black sand beaches; one where the grains are very sharp and one where the edges have been rounded over.

Black sand beaches which store the sun´s heat very well can form in a similar way from erosion of volcanic rock. The rivers cut through the black volcanic rock and erode it. As the eroded rock is carried toward the ocean it breaks up and forms small sediments by the time it reaches the ocean. These pieces of black sand have been rounded by erosion and the grinding with other sediments on their way to the ocean.

Another way that black sand beaches can form is from the hot lava hitting the cold ocean water in certain conditions. It's how the lava enters the water that causes the different beach types. When it flows directly into the water it is still very hot (anywhere from 750 to 1,250 degrees Celsius). Contact with the cold water shatters it into small shards. These shards are originally very sharp (like broken glass), black in colour and glossy like glass, but will become more rounded as the ocean waves erode them. So these pieces are either deposited right where the lava stream hit the ocean, or are carried, for a short distance, along shore by the currents and then deposited. In this case the grains will be very sharp.

Most of the black sands, which are volcanic in origin, are high in Iron and Aluminum, since these elements are found in volcanic produced materials (lava, etc.).

On continents, sand is largely comprised of quartz grains because quartz is more resistant to weathering than most of the other abundant rock-forming minerals. As a result, most sand is white to tan. In tropical and sub-tropical areas, much of the sand is derived from corraline material, and again is white to tan.
Where the "parent material" is basalt, there is little quartz and the weathering results in black sand. This is generally only found in areas with relatively recent lava flows where coral hasn't had a chance to build reefs nearby - like in Gran Canaria. Once reefs build and corraline sand begins to form, the basalt sand is often washed away and/or removed by weathering processes because it is less resistant.

Therefore, worldwide, black sand beaches are a relatively rare phenomenon.

There are many types of sands; bright lime sand consists of crushed shells, snail shells, corals and fossils. It weathered ages ago and fell apart. Black sand was made of lava stone, granite sand, were placed in the quartz and mica.
Sand can formed by water, heat and pressure again to stone. Also concrete needs sand, otherwise you aren´t able to build houses or bridges.
And glass? It consists mainly of quartz sand, which is heated for twelve hours at 1500 degrees, until it melts.

Nowadays a very important sand is the very fine one in computer chips. In tiny blocks from sand data, programs and circuits are stored electronically. Without the sand, there were no computer games, no world wide web and no Geocaching.
Well, sand is more than just building sandcastles....

ATTENTION: the black sand is best viewable if there is low tide. At high tide the beach is hardly accessible. Check the tide here: Click!

Please send us your answers to the following tasks. Don't give any hints in your log!

1. Describe the type of sand you find at this beach. Use the information mentioned above.
2. Describe the difference between wet and dry black sand.
3. What do you think? Is the sand magnetic? Tell us why.
4. How was this beach formed?
5. What do you find at waypoint two? Is there a special item attached which doesn't belong here?

Optionally:
Write ur GC - nickname in the sand and take a picture.

You can log immediately. If your answers are incorrect we will contact you.

Additional Hints (Decrypt)

Nhpu jraa qre Fnaq qnmh ireyrvgrg. Qvrf vfg xrva Fbhiravefubc. Ovggr aruzg qra Fnaq avpug zvg. Erzbiny bs fnaq vf cebuvovgrq. Yn ryvzvanpvóa qr neran fr cebuíor.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)