Quote:
Originally Posted by xoxoxoBruce
Amazing, the Columbia cut those mountains in two.
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Ready for another post about Oregon geology ???
The Columbia River and Gorge are new comers to Oregon.
It seems to have started with Lake Bonneville in Utah,
which left us with Salt Lake and the Bonneville Salt Flats,
when it drained north and westward, creating a gigantic lake
centered on what is now, Rome, Oregon.
The new lake has been named Lake Idaho by geologists, and it existed for a very long time.
But eventually, it too drained northward into the existing Snake River,
and it was these discharges that created the drama of today's Hells Canyon.
At that time, there was no Mt Hood or Columbia Gorge,
but the Columbia River became a major drainage.
In fact, the junction of the Snake and Columbia (Pasco, WA) was actually fairly close
to the then existing coast line of Oregon (near Mitchell, OR).
This was all millions of years ago. It was only 10's of thousands of years ago that
the ice ages formed Lake Missoula in western Montanta, and the ensuring Missoula Floods
that carved the Columbia Gorge out of the lava flows that had traveled from
northeast Oregon to Portland, OR and beyond to the coast.