The Eye of the Sahara and the Siberian Eye
There is a place in the western part of the Sahara Desert that many travelers would dream of visiting. Among the monotonous desert landscape stand out circles, as if drawn by someone’s giant unknown hand. This place has many names: the structure of Rishat, the Eye of the Earth, the Eye of the Desert, the navel of the Earth. This is explained by the fact that the complex of giant rings is very similar to the pupil of a human eye, framed by the contours of the eyelids.
The Rishat structure was discovered about half a century ago, in 1965, during the first space missions. Nothing surprising that before the space age, the Eye of the Sahara was not seen, because the diameter of its outer contour is about 50 kilometers, so the rings can be seen only from a considerable height. On the ground, however, everything looks like a stony desert with a succession of different lowlands and highlands. The structure was formed gradually, ring by ring. In the process of research, scientists have been able to establish the age of this geological formation of 600 million years, that is, it exists since the Proterozoic period.
The nature of the rings has long been a mystery to geologists. If you look from a distance, the picture opening to the eye seems like a destroyed volcano or a crater left by a meteorite.
There are many versions of the origin of the Lake, but we can say for sure that no volcanic rocks have been found in these places, nor any trace of a powerful impact. Scientists have found that the structure of Rishat has the shape of a truncated tectonic dome. At the time of the dinosaurs, i.e. in the Cretaceous Period, there was a dome-shaped uplift of the Earth’s crust, and then, under the influence of precipitation and winds, the above-ground part was cut off to the ground. The circles we see today are strata of solid quartzite. They form ridges about 100 meters high with steep bluffs to the center of the Oka and gentle slopes on the outer side.
Because of its huge size and clear outlines against the endless sands of the Sahara, the Eye of the Earth serves as a kind of reference point for astronauts. Thus, Valentin Lebedev, looking through a wonderful round in shape and unusual in structure geological object from a window of Salyut-7 station, realized that he associated it with a child’s pyramid, assembled from rings of different colors.
It would seem that such lifeless and mysterious landscapes should cause human fear and dread. Nevertheless, several one-story buildings, serving as a kind of hotel for thrill-seekers, have already been built here, and they are not empty.
The meteorite is to blame.
As for scientists, they still can not come to a consensus about the cause of this geological formation.
The very first hypothesis expressed by researchers was that the Eye of the Earth was a crater formed at the site of the fall of a giant meteorite. However, attempts to gather evidence were unsuccessful. Scientists have not been able to find any trace of the impact of a space body on the ground, or the consequences of this impact. The bottom of the circular formation is flat, there are no depressions, no signs of the impact wave on the rocks surrounding the Eye. In addition, supporters of the crater version failed to explain the presence of not one but several rings, perfectly embedded in each other. After all, to achieve such a pattern, several meteorites of different sizes must fall into this place with high accuracy, which simply can not be.
An extinct volcano
For a long time, the volcanic version of the formation of the rings looked the most plausible. It was based on images of ring structures found on Mars, the Moon and Mercury.
In 1985 in the textbook General Geotectonics there was even a section devoted to this phenomenon. The authors explained the origin of the ring structures as a result of an ancient volcanic eruption many centuries ago. But there is a mishap The Eye consists mainly of sedimentary dolomitic rocks, it has no volcanics at all and no traces of volcanic dome. Therefore the volcanic theory does not stand up to any criticism, despite the fact that it fits perfectly well with a perfectly round shape of mysterious rings.
When something cannot be explained, the most fantastic assumptions arise. And in the case of the Eye there was immediately a version that here millions of years ago, a spaceship of aliens landed, and the rings is a trace of it. There are even those who assure that Atlantis was here, but no one has any proof of these versions. And there are no anomalies in this region. The shepherds live quietly and feed their camels. In a word, everything is quiet in Sahara.
The version that the Eye of the Sahara has been formed in a natural way as a result of ongoing geological processes has turned out to be the most provable. According to the scientists who have put forward this hypothesis, the platform in this place has risen and fallen and has been affected by wind and water currents. After tens of millions of years of erosion, the water has washed away the soft limestone, leaving a much harder and more resistant quartzite which has created this layered formation.
But even this plausible theory does not fully explain how rings of such regular shape appeared in the middle of the desert. Which means that the question remains open for now.
The twin brother
Very similar to the Eye of the Sahara, the Siberian Eye is the Condor Range, the only ring-shaped mountain range in the world. Looking at this natural wonder, involuntarily recalls “The Lost World” by Conan Doyle. The ridge is located 1,000 kilometers north of Khabarovsk. Of course, it is much smaller than the Rishat structure – only eight kilometers in diameter, but it looks no less impressive. The ridge rises above the surrounding landscape by 800 meters and on the pictures taken from space looks like a lunar or a Martian crater.
The Evenks and Yakuts consider Kondor a sacred mountain and call it Urgula. In the northern part of the range there is a place where it splits, from here the river Kondyor flows out. This is the name given to it by the discoverers, who, apparently, compared it to camping soup (kondyor is a liquid porridge, a stew of millet with lard and onions).
Those who have been inside the ring said that the vegetation there is richer than on the outside, the fruits and berries are much larger. In addition, Condor proved to be a treasure trove of minerals, precious metals, and the world’s largest deposit of alluvial platinum. The largest platinum nuggets on the Earth weighing up to 3.5 kilograms were found here. And some of them have a crystalline form.
Since 1984 more than 50 minerals, elements of the platinum group, as well as gold and silver have been discovered at Kondyor. The ridge is in a hard-to-reach place; miners get here only by air or by winter roads. Each season more than 300 miners work in the mines, and 14 machines wash the rock, extracting a large quantity of precious metal. The infrastructure that exists here (houses, stores, sports fields, and the Platinum Palace) is only for the miners. The area is closed to tourists. What can you do, the deposit is of national importance.
Despite the active development in the area, scientists still have doubts about the origin of the Siberian Oka. There is a version that the ridge owes its appearance to a magmatic intrusion. Due to volcanic activity, molten masses fell from the deep into the upper layers of the Earth’s crust. Because the magmatic masses were pushed to the surface with insufficient force, they only blew up the surface clay shales, thus forming a round ridge. But this, alas, does not explain its perfectly ring-shaped shape…
The mystery of the “Eye of the Sahara” – Rishat structures
Among the list of the hottest places on Earth, the Sahara Desert in Mauritania, Africa is definitely on the list where the temperature can reach 57.7 degrees Celsius. Harsh and hot winds ravage a vast area throughout the year, but there is also a mysterious place in the desert; and it is known worldwide as the “Eye of the Sahara.”
“The Eye of the Sahara – Rishat Structure
The Eye of the Sahara is a stunning structure of bare rock peeking out of a sandy sea in the Sahara Desert.
The Rishat structure, or better known as the Eye of the Sahara, is a geological dome containing rocks that predate the emergence of life on Earth. The Eye resembles a blue apple and is located in the Western Sahara. Most geologists believe that the formation of the Eye began when the supercontinent Pangea began to break up.
The discovery of the “Oka Sahara.”
For centuries, only a few local nomadic tribes knew about this incredible formation. It was first photographed in the 1960s by Project Gemini astronauts, who used it as a landmark to track their landing progress. The Landsat satellite later took additional images and provided information about the size, height and extent of the formation.
Initially, geologists believed that the Eye of the Sahara was an impact crater formed when an object from outer space crashed into the Earth’s surface. However, long studies of the rocks inside the structure show that its origin is entirely Earth-related.
The structural details of the Eye of the Sahara
The blue eye of the Sahara seems surprising because it is the main prominent feature of the vast giant desert.
“The Eye of the Sahara”, officially known as the Rishat structure, is a very symmetrical, slightly elliptical, deeply fractured dome 25 miles in diameter. The age of the sedimentary rocks exposed in this dome ranges from Late Proterozoic in the center of the dome to Ordovician sandstone along the edges. Differential erosion of resistant layers of quartzite has created circular cuestas with high relief. Its center consists of siliceous breccia covering an area at least 19 miles in diameter.
A variety of intrusive and extrusive igneous rocks are exposed within the Rishat structure. These include rhyolitic volcanic rocks, gabbro, carbonatites, and kimberlites. The rhyolitic rocks consist of lava flows and hydrothermally altered tuffogenic rocks that are part of two separate eruptive centers, which are interpreted as eroded remnants of two maaras.
According to field mapping and aeromagnetic data, the gabbroids form two concentric circular dikes. The inner ring dike is about 20 meters wide and is located about 3 km from the center of the Rishat structure. The outer ring dike is about 50 meters wide and is located about 7-8 km from the center of the structure.
Thirty-two dikes and sills of carbonatites have been mapped within the Rishat structure. The dikes are generally about 300 meters long and 1 to 4 meters wide. They consist of massive carbonatites mostly devoid of bubbles. The carbonatite rocks are thought to have cooled from 94 to 104 million years ago.
The mystery of the origin of the “Eye of the Sahara”
The Riche structure was first described between the 1930s and 1940s as the Riche Crater or Riche Loop. In 1948, Richard-Molar believed it was the result of a laccolithic thrust. Later, its origin was briefly considered as an impact structure. But a more thorough study between the 1950s and 1960s showed that it was formed by terrestrial processes.
However, after extensive field and laboratory research in the late 1960s, no credible evidence was found for the existence of shock metamorphism or any type of deformation indicating hypervelocity of extraterrestrial influence.
Although coesite, a form of silica considered an indicator of shock metamorphism, was initially reported as present in rock samples collected from the Rishat structure, further analysis of the rock samples showed that barite had been misidentified as coesite.
Work to date the structure was carried out in the 1990s. A new study of the formation of the Rishat structure by Matton et al. from 2005 to 2008 confirmed the conclusion that it was indeed a non-impact structure.
A 2011 multi-analytical study of the Rishat megabreccia concluded that the carbonates in the silica-rich megabreccia were created by low-temperature hydrothermal waters, and that the structure requires special protection and further investigation of its origin.
A convincing theory of the origin of the “Eye of the Sahara”
Scientists still have questions about the Eye of the Sahara, but two Canadian geologists have a working theory about its origin.
They think the formation of the Eye began more than 100 million years ago, when the supercontinent Pangea was torn apart by plate tectonics, and what is now Africa and South America broke away from each other.
The molten rock rose to the surface, but not all the way up, creating a dome of rock layers that looked like a very large pimple. This also created fault lines circling and crossing the Eye. The molten rock also dissolved limestone near the center of the Eye, which fractured, forming a special type of rock called breccia.
A little more than 100 million years ago, a major eruption of the Eye occurred. This partially collapsed the bubble, and erosion did the rest of the work to create the Eye of the Sahara that we know today. The rings are made of different rocks of stone, which collapse at different rates. The paler circle near the center of the Eye is the volcanic rock that formed during the explosion.
“Eye of the Sahara” – a landmark from space
The Eye of the Sahara, more formally known as the Rishat structure, is a prominent circular feature in the Western Sahara Desert in Mauritania that has attracted attention since the earliest space missions because it forms a prominent bullseye in a rather unimpressive expanse of desert. .
Modern astronauts love the Eye because much of the Sahara Desert is a solid sea of sand. The Blue Eye is one of the few ruptures of monotony that can be seen from space, and it has now become a key reference point for them.
“The Eye of the Sahara is a great place to visit.
The Western Sahara no longer has the temperate conditions that existed during the formation of the Eye. However, it is still possible to visit the dry, sandy desert that the Eye of the Sahara calls home, but it is not a luxury trip. Travelers must first access a Moorish visa and find a local sponsor.
After admission, tourists are encouraged to make local travel arrangements. Some entrepreneurs offer airplane rides or hot air balloon rides over the Oko, giving visitors a bird’s-eye view. The Eye is not far from the town of Ouadane, which can be reached by car, and there is even a hotel inside the Eye.