What Was Earth Like 4 Billion Years Ago?

in the Northwest Territories of Canada alone geologists Labour's away with hammer and chisel struggling to extract a sample of rock from a smooth unyielding surface it's late in the afternoon but she doesn't need to worry about night falling in the summer field season the Sun is never far from the horizon and a pinkish Twilight rains [Music] field work in this corner of the globe is a unique challenge there are no roads out here no cafes or hotels no help if anything goes wrong this is the land of lakes and bears and the geologists are far from home they traveled to this spot first by float plane and then on foot navigating with one eye on the treacherous swampy ground the other continually on the GPS it would be all too easy to lose your way out here the spot they are aiming for looks much like any other in this wilderness but the geologists maps reveal what the eye cannot the nature of the rocks beneath their feet the geologists task is to map the changes and figure out the processes that shaped this remote corner of the globe this is the Canadian Shield a fragment of ancient continental crust finally on the shores of a shallow lake they stop to the South stands of trees of the Canadian boreal forest March into the distance but to the north the Arctic tundra is host to lower more Hardy vegetation this whole area lies under many feet of snow and ice in the winter now the ice is gone but the geologists still struggled to find the rock beneath multicolored lygian which covers every surface in a thick durable crust only where fires have swept through all frost has shattered the surface are we able to see through to the ancient rocks themselves the surface is smooth polished as if by some immense giant sweat stone but this is the handiwork of Galatia s' passing through whose incredible force is enough to grind solid rock to powder and then use that powder to grind the rocks some more erosion by this by ice water wind will be the fate of all rocks eventually but this outcrop so far survives this is what geologists call an ice a metamorphic rock with an eventful history one that is borne witness to the convulsions of the earth on a massive scale over hundreds of millions of years as continents collided the granite was crushed ached folded twisted out of all recognition when it's finally uplifted and exposed at the surface the result is this intricately striated rock which wears the scars of its torment as a badge of identity certainly it's a beautiful Rock it looks like many other gneisses all over the world starting out as igneous rock a granite that froze from magma at the heart of an ancient volcano but this nice this hard worn specimen from the far reaches of Canada is special it has seen more history than any other rock on earth when the geologist returned her precious samples to the lab when she carefully extracted the most resilient zircons and when she precisely measured the proportions of decayed and undecayed uranium atoms she was finally able to figure out its immense age for this is the Acosta nice and it is four billion years old it is the oldest rock on earth [Music] in its four billion years of the surface of the planet it's withstood the cataclysmic collisions of immense continents avoided subduction at plate boundaries and resisted the relentless onslaught of wind water and ice that have been the death of so many younger than itself so perhaps it's not surprising that rocks like this are incredibly rare what may be more surprising is that however hard geologists have searched they can't find anything older the acosta nice is old but it's not as old as the earth itself meteorites tell us that the earth formed around the Sun 4.5 4 billion years ago and yet the oldest rocks are more than half a billion years a younger more than 10% of Earth's history is missing from the record books and half a billion years is a long time it's the same amount of time that animals plants all multicellular life has been on the planet so what could be missing from this first huge chunk of Earth's history what was going on for all that time [Music] more than 500 billion years before the first crystals of the acosta nice took shape the earth was born the newborn son shown a weak and watery light over its protoplanetary disk where gravity pulled specks of dust then tiny pebbles larger rocks and eventually huge proto planets together eventually a single roughly spherical body took shape about 150 million kilometres from the Sun inside this newborn earth heavier elements like iron and nickel felt the irresistible tug of gravity and descended deep into the heart of the planet where temperatures and pressures soared the earth differentiated into core and mantle the surface of the planet exposed to the cold vacuum of space cooled and solidified into a thin igneous crust for time everything went well for the nascent earth until catastrophe struck another proto planet FEA struck scientists aren't sure if they hit the earth with just a glancing blow or if it was totaled in a head-on crash but in either case this was no ordinary bombardment with the force of a billion trillion tons Thea plows into the earth the intense pressure sees temperatures soar to several thousand degrees Celsius solid rock turns first to liquid and then to vapor both planets crusts are stripped away and huge chunks of their Mantle's are hurled out into space as the dust settles this earth of 4.4 billion years ago would be unrecognizable to a traveller from today glowing red from within the molten mantle uses through the cracks of black glossy crust it's girdled by a thick tumultuously of rock and dust the disgorged remnants of both victims Mantle's now frozen unlocked in orbit around the shattered earth but no observer from our world would last long on the planet's surface barely any atmosphere remains any gases that had cloned to the earth when it first formed would have been blown away by the spectacular force of the collision the rock ejected from the mantle rains down to the surface as molten droplets dust pebbles and boulders and the skies light up both night and day as the rocks in the encircling ring jostle and collide with one another like waves on a storm-tossed sea night and day themselves come at breakneck speed to the immense energy impacted by failures collision sent our planet reeling now completing an entire rotation in just five hours eventually some semblance of order begins to descend in Earth's skies small rocks collide and stick together and attract larger rocks which themselves have the gravity to attract more of the orbiting debris before long a single body comes to rain sweeping up the rocks and dust and clearing out Earth's skies the moon is fawn but it's not the moon we recognize today early on it glows dull red is the internal heat from its accretion slowly escapes into space as it cools it becomes a relatively featureless ball of grey rock pockmarked by only a few craters from collisions later on in its formation like the earth it's spinning rapidly and this moon looms large in Earth's skies it's ten times closer than today and from the planet's surface appears about 15 times as wide with an arm outstretched it would take an entire palm to hide it from view the earth now has a satellite weighing a million trillion tons orbiting just 20,000 miles away and this new neighbor has a profound impact on our world Thayer's impact injected an immense amount of heat into the earth the surface itself may drop below a thousand degrees celsius allowing a thin crust to solidify but throughout the interior the molten rock is still a roiling ocean and the new moon huddled so close to the earth can tug on that inner ocean like it tugs on our surface water oceans today the immense tidal forces are enough to deform the entire planet bulging it outwards cracking and splitting the thin surface crust as the semi molten rock swells and surges up as the Earth and Moon rotate around one another this towering planetary bulge rolls over the planet in an unstoppable wave splintering the crust with every rotation molten lava spills through the cracks to freeze with a glassy luster and then be broken anew mere hours later this is new earth the earth of 4.2 billion years ago if a traveler were to visit it could easily be described as the very definition of Hell itself scorching temperatures make life here unbearable the surface itself is not stable riven by lava floods and fountains of magma there is no air a sickening March of day and night overseen by the blood-red featureless face of a malevolent puppeteer this is the Hadean the first of Earth's great eons an age defined by its resemblance to Hades the underworld of Greek mythology land of the dead truly nothing can survive on this hostile hellish planet but yet this time will pass as the Earth and Moon world through space locked in a gravitational dance through the heavens they trade angular momentum slowly gradually they begin to slow down the Earth's spin slows and days and nights grow longer the moon's spin also slows and the same gravitational forces that wracked the earth now lock the moon into precise synchrony the satellite becomes tidally locked taking exactly the same amount of time to rotate on its axis as it does to orbit the earth destined to see only one of its phases from here on out the moon begins drifting away from the earth at a rate of about four centimeters a year and is still doing so today [Music] back in the Hadean as the millennia past the moon's constant face gradually shrinks from view and with it its violent tug on the battered earth the tidal wave of molten rock diminishes and eventually the thickening crust triumphs the surface of the earth is stable for now but things aren't so placid beneath the surface all that heat from the planets initial accretion and from the catastrophe moon-forming impact is still trapped within Earth's mantle it Royals with vast convection currents sending plumes of semi molten rock thousands of miles upwards from the diabolically hopped core when this material reaches the crust it punches through exploiting cracks and weaknesses in the newly formed rock to unleash great floods of lava that flow like mighty rivers and pool in hellish burning oceans these early volcanoes aren't like those of the later classic strata cone variety that blow themselves apart when they erupt their great shallow shields that sprawl across the landscape like weeping wounds losing layer upon layer of sticky black lava but it's not just lava that these giant shield volcanoes discharge as liquid rock pours over the surface gases are spewing up into the air nitrogen carbon dioxide sulfur dioxide and superheated water vapor all separated from the mantle rock and follow the volcano plumbing up and out of the earth but they don't have the power to escape the planet's gravity the gases cling to the surface building up mixing together and creating Earth's first real atmosphere a blanket of gas that swaddles the planet's surface finally protecting it from the abyss of space [Music] hi in the young atmosphere temperatures cool enough for water to condense and the first clouds form high and low pressure systems develop and winds blow between them on the highest peaks the first rain falls but this is no summer rainstorm Hadean rain burns chemical reactions in the cloud tops sees carbon dioxide reacting with water to make a potent acid acid rain falls and acid rivers flow and before long acid oceans start to pool meanwhile the turbulent mantle convection of the world begins to exert a more profound effect on the Earth's surface as streams of upwelling mantle can't escape through increasingly thick volcanic crust they spread out sideways flowing as vast and unbelievably powerful currents just beneath the young crust the rock above is torn apart and carried along with it where the huge rocky rafts diverge more lava pours out to fill the space and where they collide they're crumpled and folded uplifted and subducted mountain chains buckle upwards solid rocks splintering and shearing an excruciatingly slow motion while magma is injected from below all this is powered by the irresistible flow of the Earth's interior as plate tectonics begin plate tectonics sees the creation of new kinds of rock those of the igneous variety sitting inside the crust cooling slowly eventually forming granites acid rivers and rain gradually wear away the mountains even as they are still forming over time turning them into grains of sand that will one day become sandstone and deep in the heart of the mountains the rocks are so crushed and baked that they changed their structure and chemistry altogether they become metamorphic rocks like nice it was in the heart of one of these first mountains four billion years ago but a rock formed that was destined to stand the test of time while those around it have long since melted subducted transformed and eroded away the heart of this mountain outlives them all [Music] today it's it's resolute under a Midnight Sun protected as much by its isolation as its mineral durability it's been transported around the globe buried deep exhumed worn down by glaciers encrusted by lichens and attacked by geologists hammers but the Acosta nice has survived 90% of Earth's history it's the last remnant of our newly forged planet and a record of the hell that reigned for 500 million years if only it could tell us what it witnessed for the remaining 4 billion next time we follow the story of our planet during its earliest epochs looking at how the oceans first formed and how planetary bombardment from the heavens might have changed our world forever you've been watching the entire history of the earth don't forget to Like and subscribe tell us what you think in the comments and we'll see you in the next video [Music] you

Channel: History of the Earth

Views: 381,183

Rating: 4.9127903 out of 5

Keywords: science, earth science, paleontology, geology, geologists, geologist, earth, history of earth, history of the earth, dinosaurs, paleo, paleobotany, the moon, formation of the moon, Theia, gneiss, Acasta gneiss

Id: zirLiSIxwPM

Length: 21min 51sec (1311 seconds)

Published: Sat May 23 2020