WHAT'S HIDING UNDER THE SAHARA SANDS?

It is the largest and most famous desert on Earth. Only Antarctica is bigger, but we do not think of an ice-covered continent as a desert in the typical sense. Most people associate a desert with the scorching sun, lack of rain, and sand. Lots of sand. Only sand all around. In terms of size, Sahara covers the territory that equals half of Russia or the entirety Do you know that rich deposits of gas and oil are discovered there? The Sahara Desert has sand dunes as high as 160 to 180 meters. They are higher than a building of 70 stories. It is the Sahara Desert. But what is behind the arid, sandy landscape? Why sand? Why so much sand? Where did it come from to begin with? Has the Sahara always been like that? Imagine, not that long ago, relatively recently, these vast territories were booming with life. But then, something went wrong. What's under the sands of the Sahara? To begin with, let's start with the basic information about the Sahara. The desert is really huge, 4,800 kilometers from west to east, and 800 to 1,200 kilometers from north to south. It occupies 30% of the African continent. Its area is 8.6 million kilometers. That's more than the territory of Brazil. Is this whole vast area just sand? No. Many people would be surprised, but sand covers only 20% of the Sahara. In those places, you can observe the typical, well-recognizable landscape with picturesque dunes. The average thickness of the surface sand layer is about 150 meters. There are isolated ridges of up to 300 meters, but the rest of the Sahara is mostly rocks and cliffs. The sand, rocks, and stones hide amazing secrets, which you are about to learn. The desert is much more interesting and mysterious than it may seem. Long ago, scientists hypothesized that in the past, the Sahara was not a lifeless desert as it is now. It used to be a beautiful, blooming paradise. However, for the lack of convincing evidence, it remained only a theory until recently. Scientists found something unexpected, hidden right in front of their eyes. Under the sands of the desert, scientists found a huge reservoir, which clearly was not part of any of the ancient seas. It turned out to be left from an ancient paleolake formed about 250,000 years ago when the Nile broke through a low channel in the area of today's Wadi Tashqa Bay on Lake Nasser. The water flooded the eastern Sahara, forming a lake that at its peak covered more than 108,000 square kilometers. The size of the ancient lake was four times bigger than Erie, or two times bigger than Lake Michigan. There was also a smaller lake, about 48,000 square meters, formed at the same time. Traces of both lakes were first discovered in 2010 by U.S. National Air and Space Museum geologist Ted Maxwell and his colleagues, studying data from one of the space shuttle's radar topography missions. Using images of waterborne and windborne sediments, as well as stable rocks visible with radar under the desert sands, geologists could draw contours of an ancient megalake. The extreme aridity of the desert contributed to obtaining precise data on the prehistoric secret beneath the Saharan sands. The low humidity and the uniformity of the geological structure allowed the radars to catch all detailed features of the subsurface. Scientists located fossil fish remains found in the sediments about 400 kilometers west of the Nile River, at about 250 meters above sea level, to mark the lake's highest shoreline. By combining the data into one model, the researchers confirmed that the Nile once flooded the entire Kisiba-Tushka Depression in Egypt, creating a giant lake. The location of Paleolithic human settlements near the Salima and Tarfawi areas of Egypt also points to a presumed lake. The lake existed for many thousands of years, supporting the spread and development of a wide variety of flora and fauna. However, due to its abrupt emergence, it was doomed in the long run. The water was receding and evaporating faster than it could replenish itself. Eventually, the lake dried up, and its bottom was swallowed up by sand. But life continued to thrive in the area. Many scientific studies show that at least 5,000 years ago, the Sahara was covered in lush vegetation and filled with life. Why? In 2015, scientists could provide a comprehensive explanation to answer the question. In 2015, the Nature Communications Journal published an article that stirred up scientific circles with the results of new research. With the help of the radar observation scientific tool PULSAR, phased array-type L-band synthetic aperture radar from the Japanese satellite ALOS, Advanced Land Observing Satellite, scientists discovered the bed of a large river with an extensive network of tributaries. The Taman Rosset River is an enormous paleo-river believed to have flowed through West Africa as recently as 5,000 years ago. Its sources were supposedly in the south of the Atlas Mountains and the Ahager Mountains in modern Algeria. The river was named Taman Rosset after the oasis town in Algeria located in that area. The river, with its numerous tributaries, was over 500 kilometers long and flowed into the Atlantic Ocean in the region of Mauritania. Scientists believed that in ancient times, the Taman Rosset River basin was abundant in animals and plants. It completely dried out over 2,000 years. If the river existed today, it would have been the twelfth longest among the rivers on Earth. There is scientific speculation that the river was impermanent. It may have been appearing and disappearing for the past 245,000 years. The period coincides with the existence of the ancient lake in question. In any case, the river was a valuable water source that made the area in the middle of Africa into a blooming green paradise. Even nowadays, some traces of big water can be found there. They are famous oases of the Sahara fed by currents and underwater reservoirs hidden under the sands. The story of the Sahara is even more interesting and surprising if you dig even deeper into the sands of time, millions of years ago. In prehistoric times, everything was different. During the Mesozoic, the waters of the Tethys Protocean actually covered what is now the Sahara. The ancestors of today's whales, the Bilosaurus, lived there in great numbers. Their huge fossilized remains were discovered during the excavations of Wadi el-Hittan in Egypt. The bones of these animals remained at the bottom of the ocean for millions of years until the ocean gradually disappeared, transforming into early versions of the Mediterranean and Black Seas. The ocean floor rose up and became land. Due to the abundance of identified fossils of the ancient ocean, the Sahara is sometimes called the Valley of the Whale. Believe it or not, you can find not only ancient sea inhabitants under the sands in different places of the Sahara, but also fossilized bones of one of the largest dinosaurs, the herbivorous sauropod, which was a striking finding that generated scientific interest. The giant dinosaur reached 32 meters in length and weighed up to 60 tons. But even that discovery was far surpassed by the discovery of the remains of a previously unknown species of ancient monsters. In 2016, archaeologists made a new impressive discovery in Egypt. Egyptian and American paleontologists, led by Dr. Heshen Salim of Mansour University, dug out the fossilized bones of a creature called Mansurosaurus. Their discovery made a sensation in the scientific world. In 2018, the fossils were finally classified as a new ancient species and genus. It became a holy grail for the world of paleontology. But as amazing as the Sahara's wildlife past has been, the most interesting thing is how humans managed to live in these territories. Let us read amazing stories from dramatic pages in the history books of ancient humanity. We need to look under the sands of the Sahara. People lived on the territory of the modern Sahara for many thousands of years. Because of the variability of the climate, they came and went. They built settlements and later abandoned them. Archaeologists found human remains indicating several different communities. Some groups presumably had a higher level of organization than primitive pastoralism. The lowlands of the Fayyum and the Nabta region, with their large amount of sediment, as well as the oasis of the Bir Keseba, became habitable at a certain point due to increased rainfall. The population migrated down the Nile and from the 10th millennium BC spread across the eastern Sahara. From the 7th millennium BC, large settlements with a high degree of social organization were located there. Pottery was discovered in Nabta with the earliest samples dating to the 6th millennium BC. It is decorated with complex colored ornaments and resembles in style the Nile Valley ceramics near Khartoum. Archaeological findings indicate a higher level of social organization than the one in the Nile Valley. It is important that several ancient megalithic compositions have been discovered at Nabta. Presumably they are archaeoastronomical monuments of antiquity, like Stonehenge. There is a high probability that at least one of these megalithic structures is a calendar circle, one of the first in history. At the same time, scientists, including astrophysicist Thomas J. Brophy, suggest that these structures had applied religious meaning. According to him, the sacred symbols in the archaeological records of Nabta Playa date back to the 5th millennium BC. Their simple meaning conveys topics of great practical importance to nomad life. Earth, cattle, water, death, earth, sun, and stars. There are more man-made structures of historic interest buried under the sands of the Sahara. These are fortresses built by the Garamantes, the ancient people of the Sahara mentioned by Herodotus. They inhabited most of the territory of the Sahara from 200 BC to 700 AD. It was already a desert, but the Garamantes learned how to extract water and built canals that irrigated fields and farms and provided drinking water to towns and fortresses. Three-dimensional satellite images allowed scientists to see the smooth edges of ancient man-made channels hidden under the sands. But the dry climate gradually took over. As the channels dried up, the sand swallowed the settlements. Let us reassure our knowledgeable audience that talks of extraterrestrial creatures belong to science fiction. At the same time, the Sahara keeps evidence of interplanetary events that have survived in its sands. On the lifeless sandy bartions and rocky plateaus, you can find a very rare mineral called Libyan desert glass. This glassy rock is 98% silicon oxide SiO2. At first glance, Libyan glass looks like regular broken bottle glass of yellow-green color with numerous shades. Libyan glass has been known since ancient times. It was used to make the scarab beetle, a symbol of fertility for the ancient Egyptians, which decorated the medallion of Tutankhamen, one of the ancient Egyptian pharaohs. The medallion was first discovered by British archaeologist Howard Carter during the opening of Tutankhamen's tomb in 1916. The question of the origins of the Libyan glass is uncertain. Libyan desert glass has been dated as having formed about 29 million years ago. There is no generally accepted theory of its origin up to date. Most scientists believe that the glass formed during meteorite impact on Earth. The glass has high-temperature minerals such as bataleite, ZrO2, and muocenite, SiC, which require temperatures above 1,600 degrees Celsius to form, hotter than any igneous rock on Earth. Proponents of the comet hypothesis believe that Libyan desert glass is an altered material of comet nuclei. However, there is not enough reliable data to prove the comet hypothesis. That is why it has not yet found broad support in the scientific community. The same could be said about the meteorite hypothesis. There were no meteorite craters located near most of the Libyan glass places. It changed in 2007 when the Kibira crater, with a diameter of 31 km, was discovered 100 km away from the site of glass finds. Perhaps the Kibira crater can explain the origins of Libyan desert glass. The Sahara Desert holds many more amazing secrets. The most amazing fact about it is that it used to be like the blooming green Garden of Eden in the distant past. But the same can be in store for the future. According to Kathleen Johnson, Assistant Professor of Earth Systems at the University of California Irvine, the Green Sahara Period, also known as the African Wet Period, was caused by the Earth's ever-changing orbital rotation about its axis, a pattern which repeats itself every 23,000 years. Hence, in as little as 10,000 years, the Sahara could once again turn into the Garden of Eden. However, those estimations can be off because of anthropogenic emissions of greenhouse gases, which cause climate change. It is unclear when the Sahara will become green again, or if it will happen at all. Once again, we come to the conclusion that it's up to us. It always does.