[Intro Music]
The Pacific Northwest is famous for many things.
Including huge floods.
Floods of lava that buried almost 40% of Washington,
and floods of Ice Age water that created more than 2,000 square miles
of scab lands.
What are the odds that such rare events both happened here in this corner of
North America?
We're just south of Lewiston Idaho at the mouth of Hills Canyon,
the lowest point in the state.
The basalt bedrock here,
the floods of lava, came out of deep cracks that formed in response to a heat
source that's now, in the state of Wyoming.
A flood of water from a giant lake in Utah
came all the way through Southern Idaho, through Hills Canyon,
dropped rocks here, and the water made it to the Pacific Ocean.
A giant lake in Montana
flowed to the cascades, got backed up to here.
Each of these layers representing a separate flood.
The Columbia River basalts,
the Bonneville flood,
and the Missoula floods.
Let's dig into together and learn,
about huge floods in the Pacific Northwest.
[ Music Plays ]
The Ice Age floods have helped exposed and incredible pile of lavas
from erupting volcanoes that are not related to our famous cascade volcanoes.
The Columbia River basalt group,
a pile of lava rock more then 2 miles thick,
is an exception to the global rule.
Basalt lavas usually erupt in ocean basins,
but these low silica lavas flooded North America from below.
Much like a boat with a leak.
They're similar flood in central India, southern Brazil, southern Africa,
and central Siberia.
In each case, very large volumes of fluid basaltic magma
erupted rapidly from cracks and continents to form sheets of lava rock covering
tens of thousands of square miles.
The deep crack called fissures cracked the North American crust in south eastern
Washington and eastern Oregon, starting 17.5 million years ago.
Today many geologist agree that the fissures are directly related to the birth
of a tectonic hot spot,
beneath the out south-eastern Oregon 17.5 million years ago,
and now located underneath Yellowstone National Park in Wyoming due to the
North American plates slowly moving over the stationary hot spot.
These spectacular basalt lava eruptions,
more than 300 distinct events punctuated by thousands of years of quiet between
each lava flood.
Flooded and buried, the rugged inland landscape of the Pacific Northwest.
Many of the biggest lava flows made it from their fissures in Idaho all the way
to the tower cliffs of the Oregon coast.
At Pasco Washington the stack of Columbia River basalt lava flows is 1,600 ft. thick
more then 3 miles of lava.
Sitting on top of a 17 million year old landscape.
There isn't one visage to see all the lava flows, how could you?
To truly grasp the scale of the lava stack one has to visit scattered canyons that
expose a dozen flows at a time, like in the Yakama River Canyon,
and the Columbia River Gorge,
or in the Grand Coulee,
which was carved just thousands of years ago, not millions.
By the Ice Age floods.
[ Music Plays ]
During the Ice Age, a thick ice sheet covered much of North America,
advancing and retreating in response to global climate.
In Washington, Canadian ice crossed the border in different places.
West of the cascade range, the Puget Lobe filled the Puget Lowland with 3,000 ft.
of ice, above present day Seattle.
With