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Minas de San Jose

A cache by Três Marias Send Message to Owner Message this owner
Hidden : 06/04/2010
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Geocache Description:

Teide National Park

Teide National Park (El Parque Nacional del Teide) is a World Heritage site located in the Canary Islands of Spain from 28° 09' 00" to 28° 20' 00"N by 16°29' 00" to16°44' 00"W. Teide on the island of Tenerife is the highest mountain in Spain and at 7,500 meters (m) above the sea floor, is the world's third largest volcanic structure. It is a shield volcano that combines a severely beautiful landscape, often wreathed in cloud, with a great variety of volcanic features with uncommon altitude-adapted endemic flora and invertebrate fauna. It has been long studied. The high unpolluted location makes it a natural laboratory for astrophysical research, for monitoring climatic change and global atmospheric pollution in addition to the study of the geological processes which created it.

1,650 m-3,718 m (Teide, 3,134 m Pico Viejo).

Physical Features
Teide is the highest mountain in Spain, an impressive stratovolcano in the center of the island of Tenerife, the largest of the Canary Islands, a chain formed like the Hawaiian Islands by the passing of the under-lying lithospheric plate across a magma plume. The nominated core and associated protected areas cover over a third of the island. Its peaks of Teide and Pico Viejo rise 1,700 m and 1,340 m respectively from the encircling 16 km-wide caldera of the huge ancient Las Canadas volcano, which erupted violently 200,000 years ago. The present volcano which is the third highest in the world after Mauna Loa and Mauna Kea, rises 7,500 m from the ocean floor and was created over a long period by a low-intensity magmatic hot spot beneath an almost stationary tectonic plate. It is of great scientific interest because it concentrates in a palimpsest of successive eruptive and effusive landscapes a wide range of geological and magmatic features characteristic of such mid-plate oceanic islands. Most notable is the vast caldera of Las Canadas (the springs) created by a landslide, floored at the 2,000 m level by lava fields, walled by a 600 m escarpment of multicolored rocks, overlaid on the north side by the high volcanic summits rising out of it. The crescent-shaped floor of the caldera teems with a network of smaller volcanic mouths, cones, domes, lava channels, dikes, lavas from light felsic flows to viscid red lavas and black obsidian blocks, ochre plains of sandy alluvial deposits and red and black volcanic ejecta, scoria, lapilli and pumice, from a long series of basaltic effusions. They form the most varied collection known of volcanic structures, forms and detritus. The rocky soil is droughty but nutrient- and mineral-rich, and of many colors, in one place, Los Azulejos, greenish in cast. Under the intense sunlight the harsh red-brown desertic coloring streaked with basalt and, in season, bright with flowers, are very striking.

Visitors and Visitor Facilities
In the last decades of the 19th Century Teide became one of the first nature geo-tourism centers with the construction of the Altavista Refuge at 3,270m specifically for ecotourism (now reconstructed, with 60 beds). Now, there are about 3.5 million tourists a year, making it one of the most visited volcanoes in the world. Visitors are channeled through two educational programs: a Regulated Education program for scientists and a Public Use program served by a network of facilities and equipment, with guided tours for the public, educational lectures and school tours, training tours and environmental workshops. There are visitors' centers at the Parador de Las Cañadas del Teide hotel (Cañada Blanca) and at El Portillo which has a botanic garden of endemic plants and a fire and first aid station. There are also mountain refuges, several restaurants, a cable car with stations at 2,350 m and 3,550 m and a communications relay station. In addition to hiking, there are camping, climbing, caving and bike tours. The Park Service runs the educational Muñoz Nature Activities center just outside the Park.

This is an extract from the information on "The Encyclopedia of Earth" Website. For further reading please see the full article here.

Minas de San Jose

The pumice banks at Minas de San Jose come from the Montaña Blanca volcano, located to the southeast of the Teide-Pico Viejo complex. Its eruptions, very violent at first, sent fragments of pumice stone flying to great altitudes. It was then deposited in the surrounding area or blown by the wind to other areas, depending on its weight.

In the middle of the 20th Century the roads to the mines were asphalted, which allowed for a more intensive exploitation of the natural resources. Various open air mines were created to extract pumice stone which, due to its characteristics, has many applications like construction, cosmetics, dentistry and various chemical processes. In horticulture it is used in diverse crops, as well as in green houses, golf courses, gardens, etc.

These mines, however, had a heavy impact on the terrain. The legal reclassification of the National Park in 1981 led to a greater focus on conservation and the enormous public pressure forced the suspension of the mining activity and  the restoration of the environment of the area, as well as that of Montaña Blanca.

Pumice is composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls of extrusive igneous rock. It is commonly, but not exclusively of silicic or felsic  to intermediate in composition (e.g., rhyolitic, dacitic, andesite, pantellerite, phonolite, trachyte), but basaltic and other compositions are known. Pumice is commonly pale in color, ranging from white, cream, blue or grey, to green-brown or black. It forms when volcanic gases exsolving from viscous magma nucleate bubbles which cannot readily decouple from the viscous magma prior to chilling to glass. Pumice is a common product of explosive eruptions (plinian and ignimbrite-forming) and commonly forms zones in upper parts of silicic lavas. Pumice has an average porosity of 90%, and initially floats on water.

At the published coordinates, you can see Pumice and also other rocks corresponding to different stages of the eruptions:

The Rocks Comprising the Wall
Pumice layers
The layers of pumice are made up of fragments of very porous lava that were hurled very high into the air during eruptions with a high gas content.
When the magma contains less gas and the eruption is less violent, the lava is no longer porous, rises less high and is still molten when it falls and welds together.
Lava flows
Finally, when practically no gases remain, the lava flows over the erupting vent like an incandescent river.

Logging Requirements

Before logging, take a look at the info boards in the posted Earthcache and Parking coordinates and send us an e-mail with the answers to the following questions:
  • On your way to the Earthcache location you walk on pumices. What is the average dimension of these pumices? (If you're not good at estimating dimensions, look at the pumice depicted in the lower left corner of the infoboard at the Parking location)
  • On the infoboard at the Earthcache location, what's the name of the Mountain that is furthest to the right?

The above information was compiled from the following sources:

Additional Hints (No hints available.)

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