The Sahara Desert's Scorching Heat | How the Earth Was Made (S2, E4) | Full Episode | History

earth a unique planet restless and  dynamic continents shift and clash   volcanoes erupt glaciers grow and recede  titanic forces that are constantly at work   leaving a trail of geological mysteries behind none greater than the sahara desert the  hottest place on the planet a deadly wasteland   the time forgot or so scientists believed till  they unearthed a series of startling clues the   fossils of sea creatures freshwater shells buried  in sand ancient settlements with human remains   clear evidence that this stark  landscape hides a turbulent past one that would alter the course of  human history and provide a dramatic   new chapter in the story of how the earth was made africa's vast sahara desert  is as big as the united states the sand alone from this giant expanse could  bury the entire world eight inches deep   it's the largest desert and the hottest place  on earth when i first arrived in the sahara i   was just struck by how utterly barren it  was it's like the color green was removed   from the palette when they made this place just  nothing grays and browns and not a scrap of life   smith's mission is to unearth evidence of what  made the sahara into the wasteland it is today   her investigation begins on  the desert's far eastern edge   in egypt not in the sands of the sahara but in  one of the most epic structures ever built by man the great pyramids the building blocks of this ancient wonder house  a remarkable clue to the history of this land   from a time long before the pharaohs even existed so taking a closer look at these blocks making  up the pyramids there's actually these gorgeous   marine fossils in here most obvious are  these flat discs up to about an inch wide   they're called nummy ladies and they're  actually single-celled organisms the name numeulites means little coins in latin   they are some of the largest single-celled  creatures to have ever existed   in ancient times these blocks were  cut from quarries across the country   and dragged to the pyramid site each  block weighed two and a half tons and   it took two million of them and over  20 years to build the great pyramid and incredibly up to 40 percent of each building  block is made up of the bodies of ancient sea   creatures like these what's even more important  about the marine nemulitis is that they date back   40 million years and they only lived in  water it's piece of evidence that this   area now desert was once underneath the  ocean you think about the construction   of the pyramid but not necessarily about  what it's made of in these gorgeous fossils the sahara now is the world's biggest dust bowl  but the tiny numulites fossils suggest that   it was once very different that perhaps there  could have been water in this barren wilderness smith heads further inland to  investigate this extraordinary idea   she travels to a remote desert valley near  where the pyramid stones were quarried it's called wadi al-hitan spread out in the sand lie hundreds  of fossils first excavated in 1983   but these are nothing like the tiny numulities  that's a whale so here's the backbone the   vertebrae here's some ribs shoulder part  of the front fin and there are the jaws   this guy definitely did not live in a  desert this incredible fossil is a doradon   an ancestor of modern whales one that died out  36 million years ago so based on the size of   these vertebrae and how much of the animal  was here it was probably about 21 feet long this guy tells us that we were under  water we were in the middle of an ocean wadi is arabic for valley of the whales   this 12-mile dip in the landscape has the  highest concentration of fossils in the world   some were found in the desert floor others  in the cliff walls the count so far is 400   almost all are marine animals further evidence  that the sahara was once covered by sea so here   we've got the fossil of a baby whale you can  see the lower jaw down here with some teeth   and the shoulder the backbone some ribs  and all curled around actually the tail   comes right back to near the head as if finding  whales in the desert wasn't intriguing enough   there's yet another mystery to be solved a  lot of the fossils are a very young doradons   like this one a delicate mesh of stone helps  explain why so many baby whales died in this place   wow so finding that whale fossil told us we were  in the ocean these rocks actually tell us a lot   more about what type of ocean we were dealing  with these are all fossilized mangrove roots   these roots would have been below water the  mangrove trees would have risen above it since   trees don't grow out of the deep ocean we know  that this area was actually under shallow ocean   at the time these rocks were deposited something  probably that looked like the florida everglades   where there are mangroves growing now smith  has discovered the shoreline of the ancient sea   the shallowness of the water could explain  why there were so many young animals here   so one idea there's a bunch of these baby  whale fossils found in this area and this   would have been a shallow protected bay in that  maybe the whales came just to birth their young   it is absolutely incredible to see a fossilized  whale in a place that right now gets less than   a millimeter of rainfall a year it's as much  convincing evidence for geologic change as i   can imagine the pieces of the puzzle are coming  together to reveal the sahara's watery past so 40 million years ago this desert would  have been covered in the middle of this valley   by a shallow bay probably a brilliant tropical  blue-green color the shoreline would have been   off along the horizon some mangrove trees in  the shallowest parts of it inland would have   been a vibrant combination of rainforest and  swampland the whales would have been drawn   to this ancient shore because of the plentiful  supply of food but their ocean is about to vanish marine fossils found in europe  and africa are evidence that this   ocean stretched almost halfway around the  world and connected asia to the atlantic   it's called the tethys sea and much  of the sahara was submerged under it the mystery is how and when this lush water world  turned into the barren wasteland we see today the answer lies not in climate  patterns but in geology the entire   african continent is underpinned by  a giant piece of the earth's crust   it's called a tectonic plate and 40 million  years ago in what is known as the eocene age   it was on the move so at wariahtan we have  whales swimming around in this eocene ocean   all the while the african plate is moving  to the north africa collides with europe   closing the tethys sea but the african plate keeps  moving so we uplifted the northern part of africa   and so the tethy sea recedes and we've got this  whole area of north africa now emerged it's out   on land the whales of wadi al-hitan are cut off  and trapped in smaller and smaller pools of water   the deadly sahara has claimed its first victims in the quest to discover the history of the vast  sahara desert geologists have so far uncovered two   important clues sea fossils in the great pyramids  of egypt show these building blocks were once   under water whale bones reveal that a sea  submerged much of the sahara 37 million years ago   as the forces of plate tectonics pushed the  sahara out from under the sea it created a   tropical swamp in order to figure out what made it  into the wasteland visible today scientists have   to pinpoint the moment of its birth but the clues  to this mystery turn out to be hidden in the last   place anyone expected 20 million years ago  the sahara desert was a lush tropical swamp   geologists are now piecing together the story  of the next 20 million years today the sahara   lies in what is known as the desert belt  a region of dry air north of the equator   here strong winds clear the sky of clouds  and dry out the land below it stretches   through the gobi desert in china and across  the deserts of the southwestern united states   the sahara is the largest and yet geologists  know next to nothing about when it was created   what we have are just these little bits and  pieces these snapshots of what the sahara was like   because the wind blows away a lot of our record  and what isn't blown away is often covered by   sand so it's kind of hard to find the rocks  we need to tell the story we're trying to tell   one of the few places that shelters a clue  to the sahara's birth is the white desert in   this hauntingly beautiful site dramatic  shapes have been sculpted out of rock   oh this is great let's get that mushroom  shape these structures are called   yardangs and they are a kind of hourglass  that could help measure the age of the desert   this rock is another piece of evidence that this  desert was once under the ocean it's actually   a chalk made up of billions of little marine  microorganisms these chalks are actually really   easy to erode so that's one reason things are so  beautifully sculpted by the wind but the wind is a   brutal creator it picks up sand and hurls it at  the yardang when wind scours or sandblasts the   rocks this is the characteristic shape that we  get this mushroom shape narrower in the middle   that's because the wind goes faster as you move  up from the ground so it can erode harder but   it has less sand in it since it picks up the  sand from the ground so where we get the most   erosion where the rock is narrowest is where  we have the best mix of fast wind and the most   sand 40 million years ago the top of the  yardangs formed part of the solid sea floor   but the wind picked up once the sahara turned  to desert and the process of carving out these   shapes began figuring out how long that took  could help pinpoint the age of the desert   it's hard to say precisely how long it would  take for the wind to carve this all out   something like this about 15 feet high soft  rock you're looking at maybe only tens to a   few hundreds of thousands of years but to carve  out the whole oasis depression you've got to need   at least a million years geologists suspect  the sahara is older than a million years   in their search for a more accurate date  they next turn to its most iconic feature sand dunes here in the sahara sandstorms kick up that  can last for four days the sand is hurled   across the terrain over hundreds of thousands of  years it accumulates into dunes that can tower   50 stories high perhaps these mountains of  sand hold the secret of the desert's great age   as soon as the climate becomes arid you can start  building dunes and if we want to know how long   that took we can try and date the dunes themselves  but that's really hard what's hard is that these   dunes are constantly shifting the wind that builds  them also blows them away moving them an average   of 50 feet a year to get a precise age for the  desert scientists need to follow the sand to the   end of its journey coarse sand travels slowly and  doesn't go all that far but the finer particles   will actually travel further and so dust sized  particles actually can get carried out into the   atlantic the sahara is the largest source of dust  on the planet 500 million tons of it ends up in   the atlantic every year some of it reaches as far  as florida and creates spectacular red sunsets but   much of it settles on the ocean floor a treasure  trove of information about the sahara's past   what's wonderful about working with the  ocean sediments is that they capture   everything they they're this very faithful  recorder of the sediments that are raining   down from the surface in 1995 domenico  drilled down into the ocean floor through   layers of mud dating back millions of years  each layer of sediment is like a time capsule   shallow levels show plenty of this dust  blown over from the desert so domenical   extracted deeper core samples from over a  million years ago still there was desert dust   finally he dug down to a layer that was laid down  three million years ago and there the dust finally   stopped it had taken a voyage to the ocean floor  to uncover the turning point from humid tropical   landscape into searing desert that's a pretty  amazing change you don't think of something as   large and expansive and and fixed as the saharan  desert as being something capable of such profound   changes and yet this is what the geologic  record was telling us domenical had finally   solved the riddle of the sands the sahara has  been a desert wasteland for three million years in the search to discover the age of the sahara  geologists have unearthed two startling clues yardangs show that windblown sand has been  blasting across the desert for at least   one million years deep sea cores give  a more exact date the sahara first   turned from swamp to sand three million years ago from that moment on the sahara became  the searing wasteland we see today   it seemed that geology alone could explain  the creation of the world's largest desert   then a new radar fitted to the space  shuttle revealed a striking clue   that the desert once harbored a slash  of green across its burning sands booster ignition and liftoff in 1981 the space shuttle  made a surprising discovery   using a new type of radar nasa took a  30 mile wide scan of the sahara desert the radar pierced the sand to a depth of 16  feet and revealed what looked like a hidden   network of ancient waterways crisscrossing  the desert this finding stumped scientists   three million years ago the sahara turned  from rainforest into desert now it seemed   that it had been home to a lot of water at  some point in the following 3 million years researchers followed the nasa images north into  tunisia to the edge of a deep depression in the   sahara the site of their first clue this is what  we're looking for some quite intact shells here this deposit is largely composed of intact shells   and these are not shells from the ocean so here  we have half of a cadastral derma glaucoma shell   which is a clear sign of a freshwater  lake this is just one example of   what must be millions of shells we must be  somewhere near the shoreline of the lake here   further shell deposits reveal  that this lake was giant about the size of west  virginia but the shells provide   even more remarkable evidence  the date when this lake existed   carbon dating puts them at 90 000 years old and  leads to one conclusion to have all these shells   here we must have had a lot of rain falling in  the vicinity of this lake and a green sahara scientists fanned out across the sahara to  investigate other satellite images they searched   for any dips in its landscape that looked  like they once held a body of fresh water   so what was really exciting for me about those  radar images produced by nasa we can link this   to the gps and we're finding evidence of lakes  throughout the desert and some of these lakes   are massive three different lake locations were  confirmed by the presence of freshwater shells   the series of ancient lakes were so large they've  been dubbed mega lakes so this is the far shore   of the mega lake there's just one of many lakes  across the green sahara when drake added up the   evidence of all the lake locations he uncovered an  astonishing fact okay so if this is north africa   here and this is the edge of the sahara desert  so we're here in tunisia with a mega lake here   and we know there's another mega lake here in  southern libya an even larger one here in chad they all miss their maximum size  they would have covered 10 the sahara   that would have made them three times larger than  the great lakes what is now the biggest desert   on earth was once home to some of the planet's  largest bodies of fresh water sudden changes in   climate have been connected to everything from  volcanic activity to meteors hitting the earth but climate researcher peter domenical had a  hunch this wasn't the first time it had happened   he turned to his archive of deep ocean cores  our approach was to use deep sea sediments as   this continuous tape recorder if you will of past  climate change in africa by looking at the levels   of desert dust in cores dating back hundreds of  thousands of years he discovered the sahara had   changed more than once when we first collected  these measurements i really kind of almost fell   back in my chair because what we saw was there  are many switches like this in the climate system   to explain these regular dramatic changes  domenical looked beyond the sahara to the   rotation of the earth itself more specifically  small wobbles in the earth's orbit around the   sun the theory is that the wobble causes the  earth to tilt slightly so the monsoons which   drench southern africa today shift up  pouring rain onto the dunes of the sahara   crucially these wobbles occur every 20 000 years  so there's this perfect one-to-one match between   when africa was wet and the stage of the wobble  cycle and when this goes back millions of years   each time the rain belt moves up the landscape  is transformed and the desert turns green   to me the the single most  impressive thing about sahara is how   small fluctuations in something as  simple as a wobble in the earth's orbit   can lead to these really just totally dramatic  changes in the climate of a region that's so large   scientists now had evidence of how and why the  sahara turned green they knew that giant lakes   covered much of the desert but they had no  proof they were connected were these vast   isolated rain pools or part of an interconnected  river system as suggested by nasa's radar images nick drake gets word that in 2009 archaeologists  have made an important discovery that supports   the river theory stone tools found not far  from the site of the mega lake in tunisia   the first step is to identify the shoreline  of the ancient lake now this looks good so we've got some fresh water mollusks these  tiny shells are a good sign of the lake now he   searches for what may have been drinking the water  when the mega lake existed we have a what looks   like a part of a jawbone of a small herbivore  you can see three teeth running along there   some sort of gazelle so animals must have  existed here in the desert when it was green okay so we've got a stone tool here it's become  blunted and they've retouched it with a lot of   very fine flakes off the edge in fact  we've got stone tools and we've got   dead animals to just hunting and this was  the animal that being hunted and then we've   got water so people sitting around a water hole  waiting for animals to come to drink and then   killing them eating them leaving them behind it's an important find a stone age tool   shows people lived on the shore of this  ancient lake and 90 000 years ago was a   turning point not just in the story of the  sahara but in the history of humanity itself we are all descended from one group of people  in east africa the birthplace of humankind   sometime between 80 and 120 000 years ago modern  humans started the long journey out of africa   no one knows for certain what route they took the prevailing view is that the sahara was  impassable so humans left east africa and   traveled to the coast then crossed a  land bridge into the arabian peninsula but drake suspects that if the mega  lakes were fed by a river system   it would have created a green  corridor across the burning sands so our ancestors could have followed  these river systems gone round the lakes   follow the next river system around the next  lake and the next river system in the last lake   and then they've been in north africa  and it'll be simple for them to just   move out the lake is a good story the rivers plus  the lake is a very concrete storm to find proof of   his theory drake heads to one of the few areas  in the desert where water still flows an oasis he finds a small spring that  shelters a valuable clue cool great   cichlid fish nearly all sickly fish  are found south of the sahara desert   this particular type of cichlid is the  only example north of the sahara desert   this cichlid bears a strong resemblance to its  closest relative that lives in lake tanganyika but this lake is almost 3000 miles  away on the other side of the sahara   so the big question is how did he get it  and the most obvious answer is that it   swam across the green sahara modern humans  who could live in lots of different types   of environments would assume you found it  very easy a darn sight easier than this fish these rivers and lakes were not to last the  door slammed shut on the green corridor but   scientists now know that the earth's  wobble makes the sahara like a pendulum   it goes from wet to dry every twenty  thousand years like clockwork the   investigation has now revealed two clues  to how these wobbles affected the sahara freshwater shells dating back 90 000 years proved   the desert was once covered by giant  freshwater mega lakes a cichlid fish   shows the sahara was crossed by a river that  created a corridor of life across the sands but scientists still needed concrete information  about how rapidly these changes occurred   then an egyptian archaeologist made a stunning  discovery in the libyan desert an eyewitness   account of the sahara's last switch the most  dramatic climate change of the last 10 000 years scientists piecing together the history of  the sahara have uncovered a remarkable story   40 million years ago it was covered in ocean three  million years ago the sahara turned to desert   since then it has swung between grassland  and wasteland every twenty thousand years   scientists now turn to the  more recent geological past   the last ten thousand years to discover  how fast this giant desert can change investigators head to a valley  deep in the libyan desert the first clue to unraveling the mystery is  a small circle of stones this is essentially   the foundation of a hut ladies is unimaginable to  see an actual house structure right there next to   what is now nothing hassan's discovery is striking  evidence of human habitation the house structure   consists of this circular foundation with upright  standing blocks which are taken from the local   bedrock it would have made a semi circular  structure with probably skins and branches   and people would have used that as a shelter  hassan believes these huts could have housed   a small community of around 50 people  now he needs to know exactly when they   lived here ostrich eggshell beads these little  ostrich egg beads are clearly human handiwork   they use the eggshells to make ornamental  beads cut into a circle so that the string   can pass through so they string these into  bracelets or necklaces the eggshells the   beads were made from are also here and provide  the next clue the shells suggest of course that   they were ostriches and that's quite remarkable  for this environment to have animals like that   this was no nomadic tribe but a settled  farming community rearing animals for food   hassan carbon dated the ostrich eggshell  beads the result just seven thousand   years ago the deadliest desert on earth  was home to both human and animal life   it's dramatic evidence of the last burst of  green in the desert a dip in the desert floor   provides a clear sign that rain from the  monsoon fell here what we have here is the   evidence of a deep lake with mud deposited  this mud indicates a body of water that could   have supported a settlement of people when the  lake is deep as we can see from these layers   here then to be a lot of vegetation a lot of  animals and people would have a very good time at sites all across the sahara scientists have  excavated similar evidence of life the remains   of elephants and gazelles hippos and crocodiles  remarkable cave paintings even show people   swimming elsewhere human bones have been found  carefully buried in what were lakeside graveyards analysis of these bones reveals they date  from between 10 000 and six thousand years ago the question now for scientists was how quickly  the sahara changed from bountiful back to bone dry earlier deep sea cores had provided evidence  of the moment the sahara first turned to desert   three million years ago and of  how since then a wobble in the   earth's axis has made its swing like a  pendulum between desert and grassland now climate researcher peter dominicals  on the hunt for the sahara's last switch   from green to desert one that occurred in the last  ten 000 years to a geologist opening this core is   like a portal back in time wow that's amazing  much much redder in the upper part of the court   laid down flat every quarter inch of  sediment in the core represents 200 years   the color difference in the sediment  is subtle but to a practiced eye   it's a big clue when we split this core what is  surprising about it is that we see this in really   impressive color change and it's just it goes  from this sort of darker green brown color in   this section of the core which comes from the clay  minerals that make up the deep sea sediments this   bright red sediment actually comes from the wind  blown dust that's coming off the saharan desert   as you move along this core you can see this  color maintains itself further up and up into   the core so right now we're about seven or eight  thousand years ago boom here is the drawing of   the sahara you can put your finger on it in  this court right here five and a half thousand   years ago crucially the proximity of these two  layers reveals how quickly the switch happened   the transition from a very well watered wet  sahara that was completely vegetated to one   that was much much drier that climate transition  in this core occurred within one or two centuries   scientists knew that the sahara  was an ever-changing environment   now for the first time they had a sense  of just how fast it changed as the earth   wobble shifted the rain belt away the  return to desert was swift and deadly these transitions would have happened almost on a  generational time scale that one generation after   next after the next would have realized that  where they're living is no longer sustainable high above the ruins of the lake  settlement fekri hassan has discovered   a cave he believes was important to the saharan  people during this sudden change in climate   perhaps it holds eyewitness clues to what  happened when i first came into the cave the   sand was as high as this level and i had to crawl  in because the sand that covered the whole area   well this wind blown sand cannot  form when the desert is green buried   in the sand was the first clue some  perfectly preserved animal droppings so these animal droppings don't only  tell us about the climate at the time   but they also are excellent materials  for radiocarbon dating which allow us to   date the final event of the drawing of zara   these goat droppings covered in sand reveal a time  when a farming community was overwhelmed by desert hidden in the back of the cave is a clue  that confirms people sought shelter here   the cave has a very interesting  feature which is the prince of   hands so this is excellent evidence  of the people that lived here the next clue suggests that around them  the sahara was beginning its relentless   transformation into desert well here we see  a very interesting drawing with these long   lines this represents a  cloud with rain coming down   rain was becoming very scarce at that time and  they would have used this cave to pray for rain   but with the monsoon now several thousand  miles south their prayers could not be answered uh well this cave must have been a very  important sacred place for these people   at a time when things were getting  really bad eventually despite these   rituals the force of this change was so  great they had no choice but to leave here in this cave we have the sand and we have  the handprints which is the last message left   by the siren population the story of this  cave started with a tilt in the earth's axis   that stopped the rain falling on the sahara   what must have seemed like a never-ending drought  would in just 200 years turn a gentle fertile   region the size of the united states into a brutal  searing wilderness the wasteland we see today this would be the biggest environmental  upheaval of the last ten thousand years   those that could must have migrated  east to their closest source of water   the valley of the nile a beacon  of green in the vast desert this exodus had a surprising outcome  the death of one culture 5 500 years ago   would lead to the birth of one of the  most advanced civilizations on the planet it was a drawing of the desert that led to this  great civilization people came from different   places in the desert established their villages  and within a very short time they began to have   the basic ingredients for the rise of egyptian  civilization so climate change in this particular   case um stimulated uh one of the most spectacular  events in world history the investigation   into how quickly the sahara returns to  desert has uncovered two striking clues   ostrich eggshell beads show people and animals  inhabited a green sahara just 7 000 years ago   ocean sediments show that the sahara returned  to desert at breakneck pace in just 200 years   the next wobble in the earth's axis is set for 15  000 years from now only then will the sahara turn   lush and green again but now modern technology  is finding ways to speed up that process the investigation into the sahara desert's  eventful past now moves to the last 100 years in 1956 french prospectors discovered vast  reserves of oil in the sahara this triggered   an oil rush that led to drilling across the  desert then they struck something unexpected   under the sand huge quantities of fresh water it  seemed the sahara had another secret to reveal so this is a classic pumped well drilled  for irrigating the fields and the water is   actually pretty hot which means it's  coming up from a considerable depth   the deeper the well the hotter the water  water from wells in the sahara can reach   up to 150 degrees fahrenheit such a  high temperature means the pump is   drawing water from far enough underground  to be warmed by the earth's internal heat so pumps like these can bring up water from three  quarters of a mile underground or even deeper   with no rain for years at a time this water must  be coming from somewhere smith spots another clue   actually when i look at the surroundings of the  well i can see some orangish red iron staining   this is hematite a mineral that is typically  found in water that's been underground for   a long time combined with the temperature  this points to some kind of deep reservoir   scientists say that astonishingly great quantities  of water lie under much of the sahara the key   is in the sandstone sandstone is made from layers  of sand compacted into rock over millions of years so what's really incredible about sandstone like  this is just how good it is at holding water   and that's because there's a lot of pore   spaces between the sand grains  that are actually really big if i pour some water on this rock just like would  have happened when it rained over the sahara   it soaks right in scientists now know that every 20  000 years a wobble in the earth's   orbit shifts the monsoon north so  rain pours down onto the desert   much of that rain that fell over the sahara is  now stored underground it's called the nubian   sandstone aquifer and like a giant subterranean  sponge it sits below egypt libya and sudan though there's nothing but  sand and rock on the surface   under the ground beneath my feet is as much water  as there is in the great lakes the presence of a   reservoir even one deep underground is surprising  given the sahara's searingly hot temperatures in 1922 in neighboring libya the mercury  touched 136 degrees a record still not beaten   but ironically the water is protected by the  desert itself layers of clay encase the sandstone   the clay keeps out the harsh sun it also acts  as a sealant trapping the water within the rocks   and creating pressure fault lines in this clay  are the source of the desert's famous oases so this is a natural spring where water is coming  up from the nubian aquifer under its own pressure   this is actually fossil water it's been dated  to be up to a million years old this reserve   of water is a legacy of the sahara's lush green  past the remains of its giant lakes and rivers and this is just one aquifer scientists are  now using ground penetrating radar to locate   and map other aquifers across the sahara they  hold the promise of even more fresh water this new technology offers hope that the  desert may once more turn green reclaimed   for agriculture and farming if all goes to  plan eventually there will be 200 wells here   but drilling could prove a short-term solution  this is fossil groundwater it's not being renewed   so eventually you're going to run out water that  supported prehistoric occupants in the area and   accumulated over a million years is potentially  going to be gone in less than a hundred once the underground water  dries up the desert will   have to wait another 15 000 years before once  more the earth's wobble turns it green again the mystery of what created and changed the  sahara desert has revealed a turbulent past   whale bones in the desert show that 40  million years ago the sahara was a seabed   deep ocean cores containing wind-blown sand reveal  the date it dried up three million years ago   freshwater shells show that 90 000 years ago a  wobble in the earth's axis created giant lakes   and rivers and turned the sahara green every  twenty thousand years ostrich eggshell beads   indicate that just seven thousand years ago  the sahara enjoyed its final burst of life   before returning to desert the secrets  of the sahara have finally been revealed   this desert is not a static wasteland it's dynamic  and full of life capable of blossoming into lush   green terrain this vast majestic land continues  to shift change and evolve much like the earth itself you

Channel: HISTORY

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Keywords: history, history channel, history shows, history channel shows, how the earth was made, history how the earth was made, how the earth was made show, how the earth was made full episodes, how the earth was made clips, full episodes, How the Earth Was Made season 2 episode 4, How the Earth Was Made se2 ep4, How the Earth Was Made s2 e4, How the Earth Was Made s02, How the Earth Was Made 2X4, watch history clips, watch history channnel, Sahara Desert Scorching Heat, Scorching Heat

Id: 8SqTSZq1R_k

Length: 45min 12sec (2712 seconds)

Published: Sat Feb 13 2021

Reddit Comments

[u/bsd8andahalf_1]

well, when is the next lake going to show up?

[u/Harry_Gorilla]

It’s amazing how many things change in only 3 million years

[u/Dakens2021]

There is debate as to whether humans have ended the cycle and it is now permanent desert or not. We'll have to wait tens of thousands of years to find out. There are huge aquifers underground though. One of the greatest public works projects in history was created when Libya discovered theirs and started piping it to populated areas. Hopefully people will make others in the future and add impoundments to the Niger to recreate an ancient lake there and also divert some Congo tributary to help restore Lake Chad and create new lakes which could ease the harshness of the Sahara a bit.

[u/BaconReceptacle]

Is this the same Earth wobble that NASA recently advised will cause coastal flooding in the 2030's?