The neat thing about the Canadian Shield is that it is Precambrian
rock that has not been buried by far younger sediments. Thus you get
a window in time that is an order of magnitude greater that anything
else on Earth you are likely to check.
There are actually a lot of craters on this shield even if many are
still unidentified. At present, we are finding the elephants. Here
we discover a crater on Prince Albert Peninsula on Victoria Island
that is 15 miles across.
This is also a reminder that many craters are not easily discernible
from the air. One gets spoiled when in many cases glaciation has
scoured out the weaker rocks to form a network of lakes that scream
crater. This one took serious boots.
Massive Meteorite
Crater Found in Canadian Arctic
By Megan Gannon, News
Editor LiveScience.co
Researchers in
Canada's western Arctic have found evidence of a crater that formed
when a huge meteorite slammed into Earth millions of years ago.
Measuring about 15
miles (25 kilometers) across, the formation was named the Prince
Albert impact crater after the peninsula where it was discovered.
Researchers don't know exactly when it was created, but evidence
suggests the crater is between 130 million and 350 million years old,
according to a statement from the University of Saskatchewan.
Meteors are fragments
of asteroids or comets that enter Earth's atmosphere at high speeds;
most are small, some as tiny as a grain of sand, so they
discintegrate in the air, and only rarely are they large enough to
make it to Earth's surface. When meteors slam into Earth, they
are called meteorites.
A team of geologists
spotted this newly identified meteorite crater while surveying the
region for possible energy and mineral resources. They were initially
intrigued by steeply tilted strata visible in river gorges and other
features in the flat tundra of northwestern Victoria Island. [Photos:
Prince Albert Impact Crater]
"Unless you
recognized the telltale clues, you wouldn't know what you were
looking at," researcher Brian Pratt explained in the statement.
"You might see a bunch of broken rocks and wonder how they got
there, but we found abundant shatter cones."
Shatter cones are
surface features with distinctive wavy patterns that are known to be
created only by the tremendous force of a meteorite impact or an
underground nuclear explosion. What's more, Pratt said his map showed
that the feature is circular, which is characteristic of impact
craters.
"Impact craters
like this give us clues into how the Earth's crust is recycled and
the speed of erosion, and may be implicated in episodes of widespread
extinction of animals in the geological past," Pratt said. "It's
an exciting discovery."
There are about 180
known impact craters on Earth. Geologists think they would
find countless more if plate shifting, volcanic activity and erosion
didn't hide the evidence of most ancient impacts.
Earlier this summer,
researchers in Greenland documented possibly the oldest and
largest meteorite crater ever found on Earth. The crater, estimated
to be 3 billion years old, currently measures about 62 miles (100 km)
across. But the researchers believe its width before erosion was
likely more than 310 miles (500 km) — much bigger than the largest
visible crater, the 2-billion-year-old Vredefort crater in South
Africa, which measures 186 miles (300 km) across.
1 comment:
Right now we could use one to hit DC and end the problems this nation is under by getting rid of those that have taken over this country for their own evil desires. Ah, but I understand that it is easier to win a big lottery then it is to be hit by a meteor and none of us can wait around for a few hundred million years or more for that to happen.
Post a Comment