 |
| a panoramic view of the skeleton of Dry Falls that remains thousands of years later |
We visited the Dry Falls
Visitor Center where we watched a short video and learned even more from the
informative displays.
Here is a synopsis of what
I know:
20 million years ago the
landscape here in Central Washington was somewhat different. There were
mountains, valleys, streams and lakes, and vegetation and trees flourished in
the moist, temperate climate.
Then about 17 million
years ago, and lasting for about 11 million years, the Pacific Northwest was
subjected to some of the earth’s largest basaltic lava flows that engulfed about
63,000 square miles. Eventually, the multiple lava flows accumulated to as much
as two miles thick. The Columbia River was forced into its present course by
the northwesterly advancing lava. The
lava cooled and cracked, forming the familiar hexagonal basaltic columns.
The next phase included
the warping of the plateau by tremendous forces deep beneath the earth’s
surface, which caused the uplift of the mountainous region in the north and
caused the plateau to tilt slightly to the south.
Fast-forward to one
million years ago, with the cooling of the climate and the beginning of the Ice
Age. A vast ice sheet moved into Washington, Idaho and Montana. Near the
Canadian border, the ice sheet was up to one mile thick. The fringes of the ice
sheet dammed rivers, created lakes, and at times the Columbia River was forced
to find a new path, flowing through what is today the Grand Coulee.
A portion of northwest Montana
was covered by glacial Lake Missoula, which played an important role in the
formation of Dry Falls. The lake was held back by an ice dam, and contained as
much water as all three present-day Great Lakes combined. The climate experienced many cycles of warming
and cooling, causing the ice sheet to recede and advance. As many as 80 times the lake broke through
the ice dam with the receding of the glaciers, and unleashed tremendous volumes
of water that rushed across northern Idaho and into Eastern Washington at speeds of up to 65 mph.
Catastrophic floods raced across the plateau numerous times, ripping out the
cracked basaltic rock, etching the coulees and ravines that now characterize
this region and are known as the Channeled Scablands. Huge whirlpools sucked basalt from below,
forming deep potholes.
Two major waterfalls
formed along the course of the floods. The larger of the two formed at the
upper coulee, roaring over an 800-foot cliff. The tremendous erosion that
resulted plucked pieces of basalt from the precipice causing the falls to
retreat 20 miles and self-destruct by cutting through the Columbia River valley
near what is now the Grand Coulee Dam.
The second waterfall was formed on the sloped monocline near Soap Lake,
and erosion caused it to retreat to the current position at Dry Falls near
Coulee City.
 |
| map showing the location of Soap Lake and Sun Lakes Dry Falls in the Lower Grand Coulee, with Banks Lake above, part of the Grand Coulee - more information found here: http://hugefloods.com/Grand-Coulee-Ice-Age.pdf |
 |
| view from the Visitor Center looking down to the lake that remains below |
Once the climate warmed,
the ice slowly melted and the glacier retreated north. The Columbia River
returned to its original channel around the edge of the lava plateau.
Today, the ridge of Dry
Falls and the numerous coulees and lakes we see across the plateau are
reminders of the raging torrents that once scoured this area.
Sun Lakes Resort is situated near the base of Dry Falls, and we have hiked the trails that lead you to the lake below the precipice where we have stood and gazed up at this geological wonder towering 400 feet above us
 |
| views down the coulee - Sun Lakes Resort is beyond the lake you see |
 |
| a terrific aerial view I snagged from the Internet - you can see the 3.5 mile skeletal ridge that remains of the falls |
Here are a few links for further information about this geologic phenomenon suggested by the very helpful park ranger at the Interpretive Center: