The Earth Story

Colca Canyon, Peru This is one of two gigantic canyons found on the western side of the Andes Mountains of Peru. Colca Canyon reaches depths of over 3 kilometers beneath its rim, more than twice the depth of the Grand Canyon in Arizona.

Laguna Colorada In this image captured by an astronaut on the International Space Station, Laguna Colorada stands out as a smear of rusty red among the burnished peaks of the Andes, with snow-capped volcanoes to the north and southwest of the lake. At 4,300 meters above sea level and located southwest of the Altiplano of Bolivia, Laguna Colorada and the surrounding salt deposits and desert rocks usually unfettered by cloud cover, allowing satellites an extremely clear view of the rugged landscape. Laguna Colorada is incredibly shallow — a mere meter and a half deep — but more than 10 kilometers long. The lake is also known as the Red Lagoon, due to the red algae on the lake’s surface that flourish in the lake’s salty waters. The white spots on the lake's surface, meanwhile, are borax deposits that had crystallized out from the lake's highly saline waters.

Atacama from above Looking southeast from near the Chilean coast, the structures of the Andes are obvious from the space station. The Altiplano (aka Puna), sitting between 3 and 5,000 metres is visible in the foreground, graced by a line of young volcanoes. Between the upthrust blocks of the mountains gleam the salty white salares, seasonal salt lakes where rain gathers in outlet free basins and evaporates, leaving its cargo of minerals dissolved from the mountains behind. Near the centre of the picture a geological transition between the Altiplano and the lower altitude Sierras Pampeanas is visible. Far away to the upper left, the Atlantic coast, near Buenos Aires in Argentina. The colours reflect climate, with the nearby red-brown deserts of the western coast contrasting with the green agricultural plains of the distant pampas. The salares between them indicate a semi arid region between the two. Loz Image credit: NASA

El Cono de Arita

Rising up out of the barren salt plain of the Salar de Arizaro in Argentina's Salto province is a peculiar cone whose shape and location made many to take it for a volcanic cinder cone, though this is disputed as some sources label the lithology as sandstone and black salt. Its existence is probably linked to volcanism however due to an buoyant intrusion below making it poke out though it only pushed up a pustule rather than managing to burst its lava through the last metres of crust and so froze underground. Some 120 metres in height its name comes from the word for sharp in the local Aymara language. It was a ceremonial centre in Precolombian times, as attested by excavated artefacts.

These salares are found in one of the world's driest areas at the border between Argentina, Bolivia and Chile, near places have never seen recorded rainfall. These free standing lakes dot the landscape of the altiplano. Having no exit, they concentrate the salts leached out of the surrounding Andes by orographic rainfall as the lakes evaporate in the arid climate. They vary considerably in size depending on the amount of rain in the catchment area, though this one is the 6th largest salt flat on Earth. The area is geologically dynamic, combining active volcanoes such as Licambur (see http://bit.ly/2CrlD8j), continued Andean uplift, and occasional floods from the surrounding mountains. The salars are a source of salt for the remote communities of the altiplano, many also contain valuable lithium deposits. and Arizaro is mined for salts, marble, iron, copper and onyx (a form of travertine precipitated from volcanic hot springs) .

Loz

Image credit: 1: Ottone Scammacca via EPOD 2/3: Rodoluca88 4: Ben Stubbs

http://bit.ly/1r5exYX http://bit.ly/1GVO9YS http://bit.ly/1r5exYX http://bit.ly/1SYVFaJ http://www.rutasadventure.com/tag/geology/

Smoke in the Andean vales

Snapped from the International Space Station we have an image taken from the east over the 4000 metre Altiplano of Bolivia, with Lake Titicaca's (see http://bit.ly/2sMekny) southern tip poking into the image at the bottom left with the barren plateau in the foreground (a consequence of the rain shadow. This phenomenon is caused by the dominant trade winds blowing across the continent from the Atlantic coast, bringing the moisture that feeds the Amazon and other rivers. The air hits the Andes, rises and cools, precipitates into moisture and rains, and then, thoroughly dry hops over the mountains to desiccate the coastal strip of Chile and Peru beyond. The phenomenon is known as a rain shadow (see http://bit.ly/1I1OPAh). In the lowlands below the mountains there are dark green jungles part covered in cloud, feeding off the stream of nutrient laden water washing off the peaks. Here several forest fires are burning at the top edge of the photo, and their smoke is being drawn up the valleys, in one case passing through the 6000 m Cordillera Oriental (the chain of snow capped peaks in the centre of the image) up a river valley that has eroded headwards into the chain.

. Loz

Image credit: NASA

https://go.nasa.gov/2GvnrLd

La Laguna Colorada The altiplano landscapes of South America contain may salars, in which salt eroded from the surrounding mountains gets concentrated into closed (endorheic, meaning within flow) basins forming a unique ecosystem. This example lies in Bolivia, on the edge of the 2 million year old products of a catastrophic explosive volcanic eruption. The red colour is caused by both sediments and algae, on which the endangered flamingos that grace these wild and remote lakes graze. It is listed as a wetland of international importance and part of the Eduardo Avaroa Anean faunal reserve. Loz Image credit: Valdiney Pimenta http://www.atlasobscura.com/places/laguna-colorada http://volcano.oregonstate.edu/book/export/html/590

Sunset and night sky in the Chilean Altiplano Plateau, volcano Cerro del Leon in the background

The super-eruption that fizzled

Subduction creates powerful volcanism, reflected in the Rim of Fire surrounding the Pacific Ocean as it passes back into the mantle under the surrounding continental plates. All down the west coast of the Americas a variety of volcanic events large and small has characterised the geological history of the area for a very long time, including the super eruptions associated with the Yellowstone hotspot, and several historical ones in various parts of the Andes. Such eruptions are vast and explosive, pumping out huge layers of hot burning ash (over a thousand cubic kilometres) in repeated bursts and forming calderas as the rocks collapse into the emptied magma chamber beneath.

The lava ponds and accumulates for a long time between outbursts, sometimes millions of years, and much of it crystallises as granites without ever reaching the surface, as evidenced by the batholiths that line the entire western American coast. These were once magma chambers, bubbling and fizzing with heat, crystallisation and chemistry, though the volcanoes they once fed are now eroded, replaced by younger siblings. Many of the metal riches of the strip come from this volcanism, the granites spitting out fluids charged with metals that don't fit into the crystal structures of the rock's standard minerals, including the gold of Alaska and California and the copper that keeps Chile and Peru economically afloat.

A recent study reveals that a large accumulation of this nature happened in the Altiplano of the Andes after the last super eruption some 3 million years ago, but the ambient conditions meant that it froze in place in the crust rather than fizzing out to the surface as an eruption.

The team sampled small lava domes in northern Chile and Bolivia investigating the most recent minor eruptions, whose products share a chemical composition with the region's past supereruptive ones. They also found zircon crystals, that ever present found of multi layered geological knowledge and dated them, finding that their crystallisation spans the entire range from the last supereruption and the extrusion of the lava domes some 75,000 years ago. Modelling shows that large volumes of continually refreshed magma are necessary to produce this signature, showing that vast volumes of fresh granite must be present at depth and have fed the lava domes.

Seven such eruptions have occurred in the area in the last 10 million years, but why the latest rising batch of magma froze rather than erupting remains unknown (though it could be a lowering in flow rate from the deep crust below), as does whether the region can now be considered inactive for monitoring purposes and resources shifted elsewhere.

Loz

Image credit: Robert Morrow

http://bit.ly/2ax41Jl

Original paper, paywall access: http://bit.ly/2anSBsj

Shadowy figure dancing on the salt flats of the Bolivian Altiplano Desert.

Flowing within

The great saline lakes and salt flats that litter the high Andean Altiplano and shelves that climb up step like from the Pacific coast are endorrheic basins (from the Greek for flows within). Such rainfall as they get is seasonal, so they wax and wane, fill and evaporate as the year flows by. Some never dry out, while others such as Uyuni, the largest in the world (the size of Hawaii's big island) go from being highways with cairns marking the road to a full on lake, depending on the time of year.

The salts are dissolved from the rocks of the mountains, but since they do not flow into the sea but remain in the basin, they build up gradual thick layers, known as evaporite rocks. In this case a combo of rock salt and gypsum are ever growing over the basin floor. In an amazing photo from the space station taken as dawn is rising over the Atlantic, the shadows of the surrounding peaks are cast for many kilometres onto the gleaming white expanse of the salar. The lakes were full once upon a time, some thousands of years ago, but have been drying up since the end of the last ice age. The salar is used to calibrate satellite instruments, since its reflectivity has been well established through field work.

Loz

Image credit: NASA

http://earthobservatory.nasa.gov/IOTD/view.php?id=84853&src=fb

Hot springs, Fumaroles, Volcanoes, saline lakes, eroded sediments, yardangs, cactii, and the mirror surface of the lake in Uyuni, Bolivia (alitplano plateau)

Laguna Colorada

This mysterious looking lake is called Laguna Colorada and can be found in the southwest of the Altiplano plateau of Bolivia. It lies within the Eduardo Avaroa Andean Fauna National Reserve and close to the border of Chile. The lake is situated at 4300 meters above sea level on a plateau created through subduction-related volcanic activity. Apart from the Laguna Colorada the Altiplano hosts several other lakes, many of which are named for their colorations.

The Laguna Colorada is a shallow salt lake which owes its unusual color to red sediments and pigmentation of different algae and other microorganisms. The lake is dotted with white islands caused by massive borax deposits which represent a nice contrast to the strangely colored water.

With a length of more than 10 kilometers but a depth of only a meter and a half the lake is home to a wide variety of indigenous birds and animals including three different species of flamingoes. One of them is called the James’ Flamingo and although they appear plentiful on the shores of the Laguna Colorada they are in fact very rare and classified as an endangered species. They were believed to be extinct in the 1950’s until a small flock was discovered and they were reinstated. The flamingoes are most abundant during the summer months and migrate to warmer regions when the Altiplano’s temperatures drop during winter.

Xandi Image Credits: http://bit.ly/1VxWxDO http://bit.ly/1UlWD39 http://bit.ly/1R11uRX http://bit.ly/1QxIbiu

Sources: http://bit.ly/1RmS465 http://bit.ly/1PZsfIN http://bit.ly/1g0pp8Z http://bit.ly/1drBfHz

Salvador Dalí Desert

You might be familiar with the surreal and imaginative paintings by Salvador Dalí. His unique style and bizarre images like, for example, the famous “melting watches” inspired the name of a desert in southwestern Bolivia. It is called the “Desierto de Dalí” or “Salvador Dalí Desert” and can be found within the Eduardo Avaroa Andean Fauna National Reserve.

The desert is an extremely barren valley which shows a beautiful play of colors and strange rock formations. It has an area of 100 square kilometers and owes its colorful appearance to its volcanic origin. Different minerals cause the various shadings of the hills and mountains and the occasional rock formations result of wind erosion in this harsh environment.

Located in the central Andes on the Altiplano the Desierto de Dalí is one of many deserts of this area. The Altiplano was created by subduction-related processes and is the most extensive area of high plateau on Earth outside of Tibet. It comprises several active volcanoes, deserts, salt flats and lakes. The most known features of the Altiplano are, for example, the Lake Titicaca or the Salar de Uyuni.

Xandi

Image Credits: http://bit.ly/1UYpU1Z http://bit.ly/1Px4aXq Sources: http://volcano.oregonstate.edu/geology

Atacama from above

Looking southeast from near the Chilean coast, the structures of the Andes are obvious from the space station. The Altiplano (aka Puna), sitting between 3 and 5,000 metres is visible in the foreground, graced by a line of young volcanoes. Between the upthrust blocks of the mountains gleam the salty white salares, seasonal salt lakes where rain gathers in outlet free basins and evaporates, leaving its cargo of minerals dissolved from the mountains behind. Near the centre of the picture a geological transition between the Altiplano and the lower altitude Sierras Pampeanas is visible. Far away to the upper left, the Atlantic coast, near Buenos Aires in Argentina. The colours reflect climate, with the nearby red-brown deserts of the western coast contrasting with the green agricultural plains of the distant pampas. The salares between them indicate a semi arid region between the two.

Loz

Image credit: NASA