Salar de Uyuni in south-west Bolivia was once part of a massive prehistoric lake but today is the world’s largest salt flat. When dry it’s a barren landscape, so featureless that it’s great for perspective tricks – but during the wet season it becomes a spectacular giant mirror.

Salar de Uyuni is estimated to contain as much as 10 billion tonnes of salt, and about 25,000 tonnes is collected here each year, using the traditional method of sweeping the salt up into neat piles to dry before being carted away.

However, salt is not Salar de Uyuni’s only valuable mineral: it also contains an estimated 5.4 million tonnes of Lithium, which is estimated to be between 50% and 70% of the world’s entire lithium supply! As a vital part of many electric batteries demand for lithium is on the increase, but Bolivia has been reluctant to let foreign mining companies onto the flat, instead opting to build their own modest plant which should be operational by 2012.

In the meantime, Salar de Uyuni still helps the economy through tourism. Hotel de Sal Playa Bianca, or “The White Beach Hotel” was built right in the middle of the salt flat and constructed from the very same salt. Unfortunately, due to the difficulties in sanitation, it was closed down in 2002.

Thankfully tourists can still experience living in a house of salt at either Hotel Luna Salada or the newer Palacio del Sal, both of which are built just on the edge of the salt flat. In an effort to protect their building from degradation, the Palacio del Sal enforces a strict “no licking the walls” policy.

Tourists to the area may also take a visit to Incahuasi island, also known as Island of the Fish. Located within the salt flat it is technically not an island, and is home to no fish. If that doesn’t tempt you, you could always visit the nearby town of Uyuni, which has a massive train boneyard.

While history is full of conflicts waged between countries over territories large and small, there is one place on earth¹ that is specifically not wanted by countries which border it, who in fact are convinced that this place should belong to their neighbour rather than themselves.

The distinctly non-triangular Bir Tawil Triangle is an area on the border between Egypt and Sudan, unclaimed by either nation, and identified by the dotted border lines in Google Maps.

Given that this is pretty much just 2,000 km² of sand and rocks, it’s perhaps not surprising that neither country is particularly attracted to it, but what causes it to be so undesirable? The secret lies in the continuation of the dotted border lines to the east and north-east, which encompass a much larger area (almost 6,500 km²) known as the Hala’ib Triangle², though it is only vaguely more triangular in shape than Bir Tawil.

Note that the border to the west of the Bir Tawil Triangle is shown as a solid line. This is 22° latitude, the political border between Egypt and Sudan as defined in 1899. Egypt claims that this border should run all the way to the Red Sea, giving it control of the Hala’ib Triangle, while Sudan would get the smaller Bir Tawil Triangle.

Sudan, on the other hand, prefers the more complicated administrative border established in 1902 which would reverse the ownership of these two parcels of land. This boundary was originally established because tribes in the Bir Tawil area were of Egyptian origin, while those in the Hala’ib area were of Sudanese descent, including those in the town of Hala’ib, the only settlement of any size in the area.

Essentially, neither country claims the smaller Bir Tawil Triangle as it would mean losing control of the larger Hala’ib Triangle, the access it has to the Red Sea, and potential oil fields. In a no-doubt complicated and tense situation, Egypt has administered the larger area since 1990, but Sudan kept armed forces there until 2000, and continues to claim the area even after their withdrawal.

This has resulted in a border post on the 22° latitude border where it is crossed by a major road, but none where that road crosses the other border further north.

The Bir Tawil Triangle has no roads, but the high-res images show that at least some vehicles pass through, with tire tracks clearly visible in the sand – these appear to be areas where water gathers, with trees growing sporadically, so may be the ‘Water Well’ from which the area is named.

More information at Strange Maps.

Using the heat from the Earth’s interior to generate electricity is known as the creation of geothermal power, and in the examples featuring 2000-metre boreholes, it’s correctly believed to be a fairly recent development. In some places however, the energy from the hot parts of the Earth’s inner layers can be harvested with little more than a spade.

The area around Larderello¹ in Tuscany’s Cecina valley has an abundance of hot wells (lagoni) and natural steam fountains (sofioni), where the escaping steam leaves the ground under very high pressure at temperatures of over 200°C; making it ideal for power generation.

The gases released here also smell strongly of sulphur, which is why this is known as Valle del Diavolo – “The Devil’s Valley”.

A working geothermal generator (using a steam-powered piston engine) was demonstrated² here as early as 1904, and Larderello actually became the location of the world’s first geothermal power plant all the way back in 1913! Today, over one third of the electricity consumed in Tuscany is produced by local geothermal plants.

The whole countryside around the town is criss-crossed by large insulated pipelines transporting superheated steam from the wells to the power station.

In 2005, nearly 10% of the world’s geothermal electricity was produced in Larderello, but as more, high-tech geothermal power stations have been built around the world, this proportion has shrunk dramatically.

You can take a guided tour if you’re in the area, of which one of the highlights is a steam outlet that the tour guide opens with a remote control to create a deafeningly loud, and very impressive-looking column of steam:

You can read more about Geothermal power at Wikipedia.

If you ever need reminded of just how powerful Mother Nature can be, look no further than the city of Greensburg, Kansas.

A small community in the heart of the United States, Greensburg has had its share of severe conditions over the years. Now, thanks to the differing image capture dates, we’re able to see a dramatic before and after comparison of the most extreme weather to hit the town in its history.

The aerial view of the city shows a community very similar to many other towns scattered across the Kansas countryside. Switching to street view however is an entirely different story. On May 4, 2007, over 95 percent of the city was destroyed when a 2.7 km (1.7 mile) wide EF5 tornado¹ ripped through town. The National Weather Service recorded 330km/h (220mph) winds during the storm, which sadly killed 11 people.²

Driving around town in the virtual street car, it’s hard to find a single thing built before the tornado that remains standing today. Most of the structures visible in street view, including the water tower, were subsequently rebuilt.

Greensburg is home to the world’s largest hand dug well, which is 33 m (109 ft) deep and nearly 10 metres (32 ft) across.³ Known as the “Big Well”, its associated museum was completely destroyed by the winds, but a 450 kg meteorite stored in the museum survived, and was found a few days later in amongst the rubble⁴.

Greensburg today is rebuilding as a “green” town. Reconstruction is being accomplished with ecologically-sound building supplies. A new factory is being built near town to manufacture ultra-green modular homes, and the city will be breaking ground on a facility for four 2.5-MW wind turbines to handle all their power needs. Maybe the city’s name is a coincidence, but Greensburg may soon be the greenest town in America.

Information about the Greensburg tornado can be found on Wikipedia, and you can read about Greensburg’s rebuilding effort on their website.

Continuing our exploration of the work of Santiago Calatrava, we visit some of his more notable buildings, beginning with an in-depth look at the magnificent Ciutat de les Arts i les Ciències – the City of Arts and Sciences in his home town of Valencia.

With construction ongoing since 1996, the complex consists of five main areas, of which one (L’Oceanogràfic aquarium) was designed by a different architect.

The Palau de les Arts Reina Sofia contains 4 performance halls for music, theatre and opera in a building that many would consider designed for inter-galactic travel.

Resembling an immense eye to represent visual arts, L’Hemisfèric houses an IMAX theatre, planetarium and Laserium.

Rising behind is the skeletal form of El Museu de les Ciències Príncipe Felipe, a hands-on science museum.

Bordering the decorative pools is L’Umbracle, a landscaped park and sculpture gallery under a network of white arches.

Calatrava’s contributions also include a bridge and central plaza, both of which are currently under construction. However, apartment buildings that were supposed to have been developed in the area have been put on hold for financial reasons.

The forms seen above are reflected in two important buildings on the Atlantic island of Tenerife. The Auditorio de Tenerife on the waterfront of Santa Cruz features a 1600-seat main hall with a pipe organ and a smaller chamber hall, all contained within one of the most amazingly-shaped buildings ever seen.

Also in Santa Cruz, the Tenerife International Centre for Trade Fairs and Congresses features 40,000 square metres of exhibition and meeting space. Thanks to this week’s Street View update, we can also now see it from ground-level.

Another waterfront building can be found by Lake Michigan in the form of the Milwaukee Art Museum which was the first of Calatrava’s projects to be completed in the US. The museum’s main feature is a movable sunshade which can retract in poor weather and at night; it also has a signature cable-stayed bridge.

As with his bridges, not all of Calatrava’s buildings have been popular. The visually stunning Gare do Oriente train station in Lisbon has been criticised for cutting off the city centre from the river, and for not protecting waiting passengers from the elements.

Thanks to the many people who suggested the CAC … paco, Eduardo R. de Lima, Stolz, Arrianus, Carlos Urena, javier, Simone, antonio waller, Sebas Font, Trompie, Michael Zacherl, Pablo, andysamp, Ximet, Andros and Martin.