Influenza A virus subtype H5N1 grouping of researchers accept discovered the retreat of an ancient H2O ice canvas from the western coast of Canada occurred before than previously thought.
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| Credit: University of Manchester |
Darvill in addition to his co-authors studied the Cordilleran Ice Sheet inwards North America—which in i trial covered an surface area the size of the Greenland Ice Sheet—to amend our agreement of past times climate in addition to ancient human migration.
The retreat of the H2O ice canvas controlled when routes were opened that allowed ancient people to migrate southward into the Americas. Which road was used – in addition to when – remains a highly contentious theme with archaeologists in addition to geologists.
Darvill in addition to colleagues from universities inwards Canada in addition to the USA used a helicopter to hit remote isle locations along the Canadian coast. The squad chipped stone samples from the tops of boulders in addition to bedrock, before taking them dorsum to a lab to investigate further.
"We used a technique called 'surface exposure dating', where nosotros measured the concentration of a rare isotope of glucinium inwards rocks exposed past times the retreating ice," said Darvill.
"The isotope accumulates inwards certainly rocks over fourth dimension every bit they are bombarded past times high-energy particles – cosmic rays – from outer space. Measuring the isotope tells yous how much fourth dimension has passed since the stone was exposed past times retreating ice."
They establish sites or in addition to then the acquaint coastline were exposed at to the lowest degree 17,700 years ago, suggesting islands along the coastline were ice-free at this time. Some higher locations were exposed fifty-fifty earlier. This is important, because it suggests an early on road along the coastline of Canada mightiness accept been feasible good before an alternative, inland route.
The findings should assist archaeologists target investigations tracing the migration pathways of early on people into the Americas.
"Our endure changes the model of when this H2O ice canvas retreated inwards the past, improving our agreement of past times climate modify over western North America," said Darvill. "The novel findings add together an exciting slice to the puzzle surrounding the colonisation of the continent."
Source: University of Manchester [September 25, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
The retreat of the H2O ice canvas controlled when routes were opened that allowed ancient people to migrate southward into the Americas. Which road was used – in addition to when – remains a highly contentious theme with archaeologists in addition to geologists.
Darvill in addition to colleagues from universities inwards Canada in addition to the USA used a helicopter to hit remote isle locations along the Canadian coast. The squad chipped stone samples from the tops of boulders in addition to bedrock, before taking them dorsum to a lab to investigate further.
 |
| Credit: University of Manchester |
"The isotope accumulates inwards certainly rocks over fourth dimension every bit they are bombarded past times high-energy particles – cosmic rays – from outer space. Measuring the isotope tells yous how much fourth dimension has passed since the stone was exposed past times retreating ice."
They establish sites or in addition to then the acquaint coastline were exposed at to the lowest degree 17,700 years ago, suggesting islands along the coastline were ice-free at this time. Some higher locations were exposed fifty-fifty earlier. This is important, because it suggests an early on road along the coastline of Canada mightiness accept been feasible good before an alternative, inland route.
The findings should assist archaeologists target investigations tracing the migration pathways of early on people into the Americas.
"Our endure changes the model of when this H2O ice canvas retreated inwards the past, improving our agreement of past times climate modify over western North America," said Darvill. "The novel findings add together an exciting slice to the puzzle surrounding the colonisation of the continent."
Source: University of Manchester [September 25, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
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