Earth's REAL Lost Continents

lately i've been looking at the earth a bit differently i used to think that the world was divided in two parts land and sea where one ends the other begins right well the problem with this is that the land never really ends sure the ocean stops that's what we call the coastline but the land it keeps going underneath all the water there's still land we just don't think of it as land because well we don't see it as land in fact we don't see it at all this makes it easy to forget that the earth's sea level is purely the result of happenstance had some asteroids not found their way here much earlier in the planet's life sea levels could have been much lower than they are now and more of the planet's surface would have been exposed had even more asteroids been pushed our way we could have had a planet even deeper underwater however no matter how much water arrived here on earth the underlying geologic structures would have always been the same removing water from the equation altogether makes visible the true form of the planet what we'll discover by doing this is that continents tearing themselves apart leave behind fragments of their own bodies while magma will pour out onto the surface wherever it can literally building new landforms in the middle of nowhere when this results in features above sea level we take notice of these right away and call them islands or mountains so today i'd like to look beyond the water to the geography below to better understand how this planet works and hopefully by the end to know a little more about the earth's surreal lost land masses i'd like to start by talking about by far the largest and most well-known of these submerged features i actually made a whole video about it already but for those watching who might be new here this is zeelandia here we find a continental fragment nearly 5 million square kilometers in size over twice the size of greenland and more than half the size of nearby australia had this landmass been raised just a little higher it's hard to say whether we would have considered this its own separate continent or merely the biggest island on the planet of course we don't need to worry about that because despite having such a large rocky foundation only seven percent of the land mass actually exceeds above sea level to support land what we call the islands of new zealand and new caledonia this wasn't the case 80 million years ago however back then zealandia was packed and tight between australia and antarctica compressing its overall area in exchange for making the landmass sit much higher above the ocean but slowly as australia and antarctica broke away from one another zealandia was caught between them and was spread thinner and thinner until only the land's tallest mountains were elevated enough to stand above the ocean shedding continental peripheral crust like this is just one way huge amounts of elevated crust to make its way below sea level another way is for the land to have been born underwater this process starts when oceanic crust subsides under continental crust creating an oceanic trench followed by a line of volcanoes fueled by the decomposition of the subsiding crust the most popular example of this tends to be the andes mountains where the nazca plate is being driven beneath the south american plate creating the atacama trench before building up a 7 000 kilometer long line of mountains and volcanoes where this same process happens without the backup of pre-existing continental cross to like where the pacific plate subducts beneath the much smaller mariana plate the mountains and volcanoes are generated underwater what's been created is a landmass covering over 1 million square kilometers named after the izu the bonen and the marianas islands the izu bonan mariana arc features at least 60 active volcanoes technically this means the landmass isn't actually lost but rather is emerging it's this very same process of volcanic land building that resulted in the nearby japanese islands and in fact if you back up even further you can see the pacific plate being encompassed under several of the surrounding plates this has all led to the buildup of many volcanic chains altogether known as the ring of fire with modern sea levels these volcanic ranges look like just a few small islands but peering through the water we can see them for the mountains that they truly are the only place where this volcanism has not resulted in a significant dry land mass yet is here though had humans taken just a couple million more years to evolve we could have inherited a much longer japan as well as an even more crowded pacific rim combining these two processes together is how we begin to describe these two rises right here the anton jaba plateau and the manahiki plateau you see 120 million years ago australia and antarctica began to pull apart stretching the ocean floor between them enough to cause it to rip open this led to the outpouring of 80 million cubic kilometers of basaltic magma building the largest oceanic plateau on earth but as australia and antarctica moved further apart this huge igneous province was broken into pieces the anton java plateau is the larger of these volcanic fragments covering 920 000 square kilometers but is currently subsiding under the solomon trench fueling the building of the nearby solomon islands manahiki isn't doing much better covering 770 000 square kilometers only three small atolls cling above the water fitting almost perfectly between polynesia melanesia and micronesia i can only imagine how many ill-fated pacific island explorers set out to the sea in hopes of finding what manahiki could have been looking deeper into the pacific the influence of plate tectonics lessens and volcanism becomes the prevailing force in landscaping i guess the first thing to notice before we really get into it is just how many islands there truly are here today there are an estimated 25 000 islands peaking above the pacific ocean but it's only the tallest youngest and most violent islands that survive here and this number does not do justice to just how many volcanic islands were not able to build themselves the whole six or seven kilometers up from the ocean floor demonstrating for us just how eager magma is to break out onto the earth's surface when a certain part of the mantle continues to poke out through any available cracks that's what we'd call a hot spot or plume when magma is continuously released through a hot spot onto a moving oceanic plate a chain of islands can be left behind the most popular example of this is hawaii where the hawaiian hot spot has been active for the past however many millions of years not only has this produced the eight or so islands we see today but this has also left a trail of unseen islands that have all been eroded back under the sea this chain can be followed all the way to the pacific trench where it finally disappears beneath the north american plate for an example of what happens when hotspots inevitably fade away we can look at two very similar features the first is the mid-pacific mountains while the main body of this landmass covers approximately 770 000 square kilometers we can trace its volcanic tail much further down through the kitty boss islands with an end point somewhere around french polynesia the shotsky hess plumage follows a similar path even crossing over the path of the mid-pacific before going out to end somewhere in the middle of the ocean looking at the paths drawn in the crust by these two hot spots tells us what direction the pacific plate was moving in as it passed over with these two chains showing a roughly northwestern trend for its foreseeable history now this isn't perfect first because the plate itself can change direction and deform over time but also because hot spots themselves can shift around under the crust making these trails useful but still less than exact for understanding plate motions something else we can see by looking at these two similar features is that magmatic discharge is typically greatest at the beginning of a hotspot's life and as the plume weakens over time the islands diminish in size this is why we can see the fronts of these trails built up into notable plateau heads followed by a long tail of gradually smaller islands as the hot spot dies down in fact the head of the shotsky hess formation known as tamu massif is technically the largest single volcano on earth with a surface area of over 000 square kilometers making it bigger than even olympus moms on mars applying the same idea to the hawaiian island chain and considering just how long this hotspot has been churning out magma we can only assume that the start of this volcanism must have left behind a much larger landmass than what we're seeing today the only problem is it has since disappeared beneath russia and is likely at least partially the reason why kamchatka is so built up today meaning not only has the main body of the hawaiian continent been lost it's been erased off the face of the earth and there's no way for us to ever know what it was like but the pacific isn't the only ocean on earth meaning we still have a lot to talk about so we're going to need to move over to the indian ocean while this may in fact be the most boring ocean when it comes to islands looking below the water reveals a different story the biggest thing happening here and the second biggest lost landmass i'll be talking about is kurgulin plateau active for 130 million years the kerguelen hotspot has produced an igneous province stretching over 1.2 million square kilometers or over half the size of greenland but this isn't even the full story as 120 million years ago before antarctica had fully torn itself away from australia this hot spot built up rock on both sides of the oceanic rift as the continents were driven further away a 300 000 square kilometer chunk of the kerguelen landmass was kept by the australian plate transporting the feature known as broken ridge thousands of miles away from its origin while it is exciting trying to imagine a world with more of this microcontinent exposed looking at the small collection of islands that do remain here shows us that the local climate would have been very cold for example the tiny kyrgylin islands feature extensive glaciers even now and most of the mass sits even closer to antarctica that being said kerguelen plateau also reaches all the way up to 45 degrees south theoretically placing the northern realm into the temperate zone showing that with enough precipitation kerguelen could have featured its own thriving exotic flora and fauna as to who would have been the first to discover and inhabit such a place we can only speculate now austronesians departing from the indonesian islands made it all the way to madagascar by as early as 350 bce leading me to believe they could have made it here as well but having originated in the tropics i'm not sure how enthusiastic these people would have been about colonizing a sub-antarctic land and so it likely would not have been until the european age of exploration that larger populations better equipped for the environment would have arrived in the end kerguelen likely would have ended up resembling new zealand both in terms of landscape and demographics broken ridge on the other hand would have experienced a climate similar to southwestern australia a much better environment for migrating people groups and likely would have been significantly populated upon the arrival of europeans looking right beside broken ridge however we'll find a plateau of similar elevation but a radically different shape running almost parallel to 90 degrees east the 90 east ridge is another product of a plate being dragged across a volcanic hot spot only this time instead of building a chain of sea mounts a more continuous land mass was constructed the result being a single 5 000 kilometer long landform only coming to an end where deposits from the bengal fan mask any further buildup in total 90 east covers an area of over 740 thousand square kilometers and that's not even including the osborne plateau had this been above the sea we could have ended up with a very strange line of land running straight from myanmar deep into the center of the indian ocean it's hard to guess the implications this land mass would have had for both human and natural history but at the very least i can say this would have acted as a solid wall against ocean currents interrupting and or redirecting the global transport of water potentially altering weather patterns in drastic and unpredictable ways the rest of the notable features in the indian ocean all come from the messy breakup between india and africa this divide was driven by the central indian rift which in turn released a huge outpouring of magma building what's known as the deccan traps in southern india as the rift forced the subcontinent to move further and further away the hotspot fell over parts of the newly created ocean building an extension off the indian coast called the chagos lakkadive ridge leaving a much longer indian subcontinent than meets the eye what igneous material from this deccan event ended up on the other side of the rift combined with pre-existing continental scraps to form the mascarene plateau while the islands of seychelles and mauritius cover only 0.8 percent of the 300 000 square kilometer land mass parts of it sit just eight meters below sea level meaning that only a couple thousand years ago during the last ice age when sea levels were up to 130 meters lower than modern sea levels much more of the masquerine plateau poked above the surface to become a much more sizable mid-indian archipelago the masquerine wasn't the only scrap of crust to come apart from africa however and it's easy to forget that india and madagascar stayed together at first it was only 50 million years or so after splitting from africa that madagascar started to lag behind eventually crumbling away into the island we're familiar with now but just like the masquerine and really all of these there's more than what you're seeing here in fact the madagascar land mass extends much further south over an area roughly equal to what sits above sea level today together this makes the madagascar land mass approximately 1.1 million square kilometers nearly as big as kyrgulen and the third largest lost or well at least partially lost continental fragment on earth the southernmost part of the plateau what's called walter's shoal sits just 18 meters below sea level meaning that at least a portion of this greater madagascar was also dry just a few thousand years ago during the last glacial maximum this still isn't the end of the story however as antarctica used to cling to africa's southern end until the southwest indian ridge tore them apart leaving two large pieces of tectonic debris behind to become the mozambique and algol house plateaus both of these landmasses measure roughly around 200 000 square kilometers and altogether help reveal the open wound that is the southeastern side of africa moving around the cape of south africa we finally enter the atlantic ocean and don't need to look long before finding another exceptionally weird landmass jutting off the side of the continent this 280 thousand square kilometer peninsula is walvis ridge the result of you guessed it a volcanic hot spot as the supercontinent gondwana broke apart the two biggest pieces of it were split by the mid-atlantic rift differentiating africa from south america magma escaped through this rift continuously building this ridge out until volcanism from the tristan hot spot diminished where this igneous material fell on the western portion of the rift the large province of rio grande rise was built up as well creating an almost symmetrical basalt deposit on either side of the mid-atlantic ridge while only 130 000 square kilometers this is another landmass that's made far more fascinating when considering what it could have been like today adjacent to the atlantic rainforest of brazil these islands could have hosted rich rainforests like none other on earth while it's again unknowable if humans would have made it here in ancient history exploring europeans definitely would have found it around the same time the rest of the americas were being discovered sitting on the portuguese side of the treaty of tordesillas it's only logical to assume that portugal would have taken possession of these lands from whatever unfortunate locals might have found their way here prior to this as portugal tried to capitalize on their new world claims this likely would have served as the first to stop for portuguese slave traders on their way from africa this would have given the rio grande islands which i suspect would have been named something along the lines of magellan a diverse modern population with a shameful history much like well yeah everywhere else in the americas whether these islands would have become part of brazil or would have stayed a part of portugal's sneaky atlantic island empire is unknowable perhaps they even could have been an independent nation another member of that lusosphere and i'll be the first to say i wish this existed not because i care too much about the portuguese speaking world let me be clear i don't but rather because every other continent besides south america already have their own associated islands north america gets the caribbean europe has great britain and ireland africa has madagascar east asia has japan australia has new zealand heck even india has sri lanka but what does south america get the falklands the rest of the atlantic is actually quite boring as the mid-atlantic ridge represents one of the cleanest tectonic brakes on earth for things to get more interesting we'll have to look all the way up here where the north american eurasian and african plates form a triple junction in the ocean this crowded tectonic zone has once again created openings in the crust 4 magma to escape through building up the azores plateau to approximately 250 000 square kilometers producing the few scattered azores islands as the ocean rift continues to push the surrounding plates in three different directions this landform will eventually be broken into three for the meantime however volcanic activity is still present across a few of the islands suggesting that this land mass isn't even done being born yet finally this brings us to the upper reaches of the atlantic where sitting beside the islands of britain and ireland is an equally massive landmass called the rock all plateau stretched thin by the breakup of europe and greenland rocko represents the largest piece to come off the crumbling continental shelf despite sitting higher north than most of britain or ireland rockwall sits directly in the path of the gulf stream which transports the warm waters from the caribbean all the way up here and beyond this means we could expect rockall to have a similar climate and landscape to its neighbors likely featuring a colder and rockier north but a warm and grassy south considering the celts made it all the way to ireland i don't think it's a stretch to say this would have become another celtic nation kept safely out of reach of those damn anglo-saxons of course no matter how impactful any of these landforms might have been we know in the end it wasn't meant to be for any of them the surface of the earth is messy and no matter how much water there is here there will always be more to discover but hopefully now when you look at a map of the earth you will see more than just land and sea [Music] hey everyone thanks for watching this video got a little longer than my usual video but judging by the fact that you're listening to me right now i'd say you were fine with that lucky for you even after 20 minutes i didn't get to mention everything i wanted to so if you'd like to see another video like this then you can head over to my patreon to help support me making these videos if not then well maybe just subscribe to see my next video when it comes out thanks

Channel: Atlas Pro

Views: 1,041,855

Rating: 4.9256058 out of 5

Keywords: education, geography, science, atlaspro, ocean, lost, continent, atlantis, new, zealand, zealandia, kerguelen, volcano, plate, tectonics, hidden, underwater, mountain, doggerland, azores, lemuria, alternate, history, sunken, volcanic, island, pacific, atlantic, rockall, plateau, java, ontong, manihiki, hawaii, rio, grande, rise, ancient, indian, sea, forgotten, secret

Id: NmFUFnMj5Jw

Length: 19min 47sec (1187 seconds)

Published: Mon Oct 26 2020