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  • Sunken relics,

  • ghostly shipwrecks,

  • and lost cities.

  • These aren't just wonders found in fictional adventures.

  • Beneath the ocean's surface,

  • there are ruins where people once roamed

  • and shipwrecks loaded with artifacts from another time.

  • This is the domain of underwater archaeology,

  • where researchers discover and study human artifacts that slipped into the sea.

  • They're not on a treasure hunt.

  • Underwater archaeology reveals important information

  • about ancient climates and coastlines,

  • it tells us how humans sailed the seas,

  • and what life was like millennia ago.

  • So what exactly can we find?

  • At shallow depths mingled in with modern-day items,

  • we've discovered all sorts of ancient artifacts.

  • This zone contains evidence of how our ancestors fished,

  • how they repaired their ships,

  • disposed of their trash,

  • and even their convicted pirates, who were buried below the tide line.

  • And it's not just our recent history.

  • 800,000-year old footprints were found along the shore in Norfolk, Britain.

  • In these shallow depths,

  • the remains of sunken cities also loom up from the seafloor,

  • deposited there by earthquakes, tsunamis, and Earth's sinking plates.

  • Almost every sunken city can be found at these shallow depths

  • because the sea level has changed little in the several thousand years

  • that city-building civilizations have existed.

  • For instance, in shallow waters off the coast of Italy lies Baia,

  • a Roman seaside town over 2,000 years old.

  • There, it's possible to swim among the ruins of structures

  • built by Rome's great families, senators, and emperors.

  • And then there are shipwrecks.

  • As ships grow too old for use, they're usually abandoned near shore

  • in out-of-the-way places like estuaries, rivers, and shallow bays.

  • Archaeologists use these like a timeline to map a harbor's peaks and declines,

  • and to get clues about the historic art of shipbuilding.

  • At Roskilde in Denmark, for example, five purposefully sunken vessels

  • reveal how Vikings crafted their fearsome long ships 1,000 years ago.

  • When we descend a bit further,

  • we reach the zone where the deepest human structures lie,

  • like ancient harbor walls and keys.

  • We also see more shipwrecks sunk by storms, war, and collisions.

  • We're still excavating many of these wrecks today,

  • like Blackbeard's ship,

  • which is revealing secrets about life as an 18th century pirate.

  • But past 50 feet, there are even deeper, better preserved shipwrecks,

  • like the wreck at Antikythera,

  • which sank during the 1st century BC.

  • When it was discovered, it contained statues,

  • trade cargo,

  • and also the earliest known computer,

  • a mysterious device called the Antikythera mechanism

  • that kept track of astronomical changes and eclipses.

  • Today, it gives archaeologists vital information

  • about the knowledge possessed by the Ancient Greeks.

  • It is in this zone that we also begin to find aircraft and submarines,

  • such as those from the World Wars.

  • Plunging as deep as 200 feet,

  • we can find some of the earliest and rarest signs of human history.

  • Prior to 5,000 years ago, there was a lot more dry land

  • because glaciers trapped much of the water that now forms the sea.

  • Our ancestors spread across these lands,

  • and so on the sea floor, we find their camps,

  • stone tools,

  • and the bones of animals they hunted.

  • These sites give us invaluable knowledge about our ancestor's migration patterns,

  • hunting methods,

  • and technologies.

  • In the deepest zone, no human has ever walked.

  • This area has been submerged since well before mankind evolved.

  • The only artifacts we find are those that have drifted down from above,

  • like NASA's Saturn V rocket engines at 14,000 feet,

  • and the deepest shipwrecks.

  • The ocean is like a huge underwater museum

  • that constantly adds to our knowledge about humanity.

  • With only a fraction of it explored,

  • discoveries are sure to continue long into the future.

Sunken relics,

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B2 TED-Ed sunken zone deepest ancient underwater

【TED-Ed】How much of human history is on the bottom of the ocean? - Peter Campbell

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    Jenny posted on 2016/11/09
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