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A Volcano-ful of Salt EarthCache

Hidden : 04/24/2008
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Geocache Description:

Naturally-occurring salt pans in the crater of an extinct volcano.

This cache involves a short walk and a swim if you like. Don't forget your sunscreen, drinking water and a hat!

I've been informed that there is now an entry fee of 5.5 Euro. And if you want to shower off the salt, take another Euro for that. (Thank you btrodrigues for the information)

In the late 18th Century, salt was so important to the local economy here in Cape Verde that this island itself was named after it - Sal.

To get to these Salinas, you need to be driving a 4x4. Head into the village of Pedra de Lume and turn left off the road by the little church, turning back on yourself to follow the old wooden pylons. Park at the entrance to the tunnel (N16 46.082, W022 53.769)

All the day and half-day tours of the island will stop here too, and should give you enough time to complete the cache if you don't want to drive yourself.

The crater of an extinct volcano forms a natural shallow basin. The bottom of the crater is below sea level and salt water reaches it naturally with no assistance from pumps, through channels beneath, to lie in shallow pans (which have been improved by man-made levees) and evaporate in the tropical sun.

As the water in each pan evaporates, the concentration of salt becomes higher. Algae in the water change colour depending on the concentration, giving some spectacular effects.

The salt is harvested and packaged at the small factory, before being carried away on an ancient tractor and trailer, out through the tunnel and down to the village and roads to the rest of the island.

Back in the C18th when the site was first industrialised, the salt was loaded onto mules, and later a cableway was built to carry it up out of the crater and down to the then prosperous port, where now only hulks of the transport ships still sit, rusting away to nothing. Currently there is no salt exported, and the tiny amounts mined now are taken by road the 5km to island's capital, Espargos.

You may bathe in the salt pans, but be very careful not to let the salty water into your eyes or mouth.

To log this cache you will have to make some observations, perform a short experiment and post a photo of yourself at the site, in "Dead Sea" pose with a newspaper if you like, or standing in front of one of the pans.

Contact me through my caching profile with the answers to the following:

Firstly, observe how many different colours of salt pans there are when you visit, and send me a list of the colours.

Secondly, choose two pools of different colours, and find out which has the higher concentration of salt, by floating something in them and seeing in which it floats higher. This can be yourself, if you like; if you don't want to get salty use another buoyant object instead, but be careful not to introduce anything that might pollute the salt pans! You will have to bring whatever "scientific equipment" you use with you, there's nothing you can find at the site that will help you. Let me know your findings. If you can't tell by observation which is saltier, you may have to do a little general research into salt pans to get an answer.

The Island of Sal was discovered on December 3, 1460 and named Llana before being renamed after the salt. The volcano has not erupted in known history but was responsible for creating the island originally, 50 million years ago. Only one island in the archipelago of Cape Verde has an active volcano, Fogo, some 250km away, which last erupted in 1995.

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