Cotopaxi

Cotopaxi is the sight to behold. Towering above the neighboring Andean peaks in north-central Ecuador, South America, it is an almost perfectly symmetrical volcanic cone. Dominating the capital city of Quito skyline to the south, 19,348 feet in elevation, Cotopaxi is the second highest peak in the Ecuador and the highest continually active volcano in the world. Its flanks are largely covered by permanent fields of snow and ice. And it is the snow that presents the greatest peril when the volcano intermittently erupts. Cotopaxi means "Smooth Neck of the Moon" and the native people have worshiped the mountain for centuries.
Cotopaxi's shapely profile was a long time in the making, for it is actually composed of two volcanic structures, with the newer one superimposed on its ancient ancestor. The older volcano called Picacho, was formed long before any of the neighboring extinct volcanoes in this area of the Andes. Traces of its caldera (a giant crater like cavity formed when a volcano's top collapses in an explosion.) are still visible on Cotopaxi's flanks.

Cotopaxi is known as a Stratovolcano: built up with lava flows alternating with layers of ash and other volcanic materials that were exploded from its vent. But the most deadliest effects of its eruptions result from Lahars - gigantic avalanches of mud and meltwater that periodically come flooding down its flanks. The first recorded eruption of Cotopaxi was in 1533. Of the many that have occurred since then, the worst took place in 1877. The explosions were heard over a radius of more than 200 miles, clouds of ash and pumice completely darkened the midday sky and the accompanying lahars killed thousands of people. Evidence of that catastrophic flow can still be seen throughout much of the countryside of the Sierras. Though Cotopaxi remains active, it has been long since the last large eruption.

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Wind Cave

Wind Cave, located in the rugged Black Hills of South Dakota is one of the world's longest and complex cave. It was named for its very strong air currents that pass in and out of its entrance. Changes in barometric pressure rises apparently trigger these eerie winds. When the atmospheric pressure rises outside the cave, wind rushes in; then when the outside air pressure drops, the air rushes out again.
Wind Cave is remarkable for its unrivaled displays of the delicate rock formation known as Boxwork - The nature's intricate art wonders!. Boxwork is found in small amounts in other caves, but perhaps in no other cave in the world is boxwork so well-formed and abundant as in Wind Cave. [Boxwork is made of thin blades of calcite that project from cave walls and ceilings, forming a honeycomb pattern.] When the limestone containing the cave was uplifted some 60 million years ago, it was broken up by networks of intersecting cracks. Over long periods of time, seeping water deposited veins of the mineral calcite in the cracks. Later, when the cave was formed, the enveloping limestone was eroded away, while the more resistant calcite in the cracks was left projecting from the ceilings and walls in fragile, beautifully intricate patterns.
The Wind Cave National Park has a number of unusual attractions above the ground as well, 28,295 acres of mixed-grass prairie, ponderosa pine forest, and associated wildlife are the main features of this park.

Torcal De Antequera

Torcal de Antequera is a limestone plateau in the mountains about 20 miles north of the port city of Malaga (Spain) on the mediterranean sea. All across the surface of the plateau, strangely eroded rock formations suggest the ruins of an ancient city. Oddly realistic sculptural forms and huge bastions that resemble ruins are seperated by labyrinths of alleys and rubble-strewn trenches.
No city ever rose on this site, however the ruins, in fact are the typical remnants of erosion in a limestone landscape. The limestone here, more than 2000 feet thick, was long ago broken up by vertical and horizontal fractures. At a time when the water table was high, the underground streams coursed through the fractures. The water dissolved the limestone and gradually enlarged the openings into a maze of galleries and chambers. Eventually the roofs of the tunnels caved in, forming the trenches - the streets and plazas of the ruined city. Ever since they were exposed, the rocky bastions that were left standing between the trenches have been attacked by wind and weather, which have gradually softened and reshaped their contours.
Meanwhile the water continues to work its way through the limestone that makes up the Plateau. Seeping through fractures at lower levels beneath the eroded surface, it is carving out new networks of channels, chasms, and caves. In time the ceilings may once again collapse, thereby revealing another, presently hidden underground landscape.

Dolomites

The Dolomites are a series of mountain groups in north-eastern Italy, in the Italian Alps.

The Dolomites' cliam to fame is not great height: the tallest peak in this part of the Italian Alps, Monte Marmolada, reaches up only 10,964 feet. What makes Dolomites memorable is their incredibly bold contours, with stark, sheer-walled massifs rising straight up from gently inclined lower slopes. The contrast is especially striking in winter, when snow blankets the valleys and slopes but not the somber walls of stone. Looming against the horizon are massive rock formations that resemble needles, spires, castles, and fortresses. Saw-toothed ridges tower over distant valleys, while vertical walls rise straight up for 3300 feet and more. Dolomites are actually originated in a warm, shallow sea. Some 200 million years ago water covered the region, and a coral reef developed atop much older beds of shale and marl. Over the millennia the coral was compressed into a distinctive type of limestone that contains magnesium. Known as Dolomite, it was named after the 18th century French geologist Deodat Dolomieu, who first described the rock. During the period of mountain building that began 65 million years ago, the Dolomites were uplifted along with the rest of the Alps. As the mountains were rising, the forces of erosion began their work of wearing down. Valleys developed where the softer, more easily eroded shale and marl were exposed. The harder Dolomite, in contrast, wore away much more slowly. As a result, great mass of Dolomite remain more or less intact, forming the stark massifs that now typify this part of Alps.

Eyjafjallajokull Glacier

Iceland is the best place to study about Glacier and glacial landforms. Almost all types of Glaciers are found here, ranging from the small cirque glaciers to extensive glacier caps. Glaciers are classified based on their size and relationship to topography. The smallest glaciers are confined to mountain valleys. These are called Valley glacier or Alpine glacier. Larger masses of ice cover an entire mountain range or volcano. These glaciers are called Ice caps and most glaciers in Iceland classify as Ice caps.
Eyjafjallajokull is the fifth largest glacier in Iceland. It is situated to the north of Skogar and to the west of Myrdalsjokull. The ice cap of the glacier covers an active stratovolcano with a summit elevation of 1666 meters, and a crater of 3 to 4 Km in diameter and has erupted rather frequently since the ice age. The last eruption was in 1821 - 1823, causing a fatal glacier run. And most recently erupted again in 2010. This recent eruption is thought to have begun on 20th march 2010, about 8km east of the top crater of the volcano. This first eruption in the form of a fissure vent (a linear volcanic vent through which lava erupts, usually without any explosive activity) did not occur under the glacier and was smaller in scale than had been thought by some geologist. On April 14th 2010, Eyjafjallajokull resumed erupting after a brief pause, this time from the top crater in the center of the glacier, causing meltwater (water released by the melting of galcial ice) floods to rush down the nearby rivers, forcing 800 people to be evacuated. This second eruption threw volcanic ash several kilometer up in the atmosphere and also has created a rare electrical storms.
Nature is admirable, peaceful and pleasant when it is silent but once active it is disastrous!

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