My second great grandfather, Thomas Condon, was the pioneer geologist of Oregon.  He arrived in Oregon in 1853 and spent half a century exploring Oregon's fossils and contemplating its ancient history.

He wrote a book, entitled Two Islands.  He determined that Oregon had anciently been covered by a sea.  The only land showing above water was the Blue Mountains and the Klamath Mountains or Siskiyous.  Oregon was drowned in water.

Geologic forces like plate tectonics, volcanism, and earthquakes raised the Oregon landmass to where we are today.  Most of the time we're wishing for more water, but there were multiple other times in our history when Oregon had much more water than it could handle.

In the 1920s  a geologist by the name of J Harlan Bretz became fixated on what could possibly have caused the vast scablands of eastern Washington.  He theorized that only a flood of cataclysmic proportions could have gouged the landscape so severely.  All the soil was removed.  Massive potholes up to 120 feet deep were bored into solid rock.  Gigantic dry falls were left which to his mind could only have once been waterfalls much bigger than Niagara.  Layers of basalt rock were stripped off 25 to 50 feet thick.

He put forth his theory, and was laughed at by other geologists.  They, one and all, believed in uniformitarianism.  The belief was that geologic processes all take place slowly, over eons of time.  In their then-current way of thinking there was no room for cataclysmic events.  Where, they asked, could the amount of water have come from that would have been required to make the scablands?

J Harlan Bretz stuck to his theory.  He knew what he was seeing.  He ultimately decided that an Ice Age glacier had dammed Clark Fork River, Montana's largest river, a tributary of the Columbia.  A giant lake had formed which was 2,000 feet deep, and was the equivalent of the combined volumes of Lakes Erie and Ontario.  He explained that the 2,500-foot-high glacier eventually gave way and released the lake's water in one giant rush.  In his mind's eye he could see a 500-foot-high wall of water rushing across eastern Washington preceded by a hurricane-force wind of its own making.  He could see the water creating Palouse Falls, thundering through Walula Gap, filling the Columbia River Gorge, widening it, and backing the Snake River up causing it to flow backwards.

He went looking for evidence, and found it in gravel beds and sand bars and in the presence of erratic rocks sitting on the tops of hills.

An erratic rock is a rock out of place.  On a hilltop outside of Sheridan, Oregon I visited a 90-ton rock nearly as big as my living room that shouldn't have been there.  It is a rock that came from Canada.  Anciently it had been caught up and carried by a glacier.  It became part of the ice dam that blocked Clark Fork River.  The ice dam broke into icebergs which were carried downstream by the flood.  That rock, and hundreds more, rode their icebergs across Washington, down the Columbia, and out into the Willamette Valley which was covered 400 feet deep by the floodwaters.  The icebergs snagged on the tops of hills as the water receded, and left them permanently planted hundreds of miles from their origins.

The wonderful, deep soils of the Willamette Valley exist thanks to sedimentation from the flood.  The Willamette Valley's soils used to be Washington's.

J Harlan Bretz doggedly pursued his cataclysmic flood theory for years despite the abuse and laughter from contemporary geologists.  Finally he was able to convince one prominent geologist to come take a look.  He showed him Palouse Falls, a 600-foot-wide ancient waterfall with a 200-foot-deep plunge pool.  The geologist swallowed his pride, and said, “How could anyone have been so wrong?!”

The geologic world came around to J Harlan Bretz's thinking.  It took until the 1960s.  It is now thought that the Missoula Flood, as it has come to be known, happened not once, but many times.  The argument now is not if it happened, but how many times.  Some say 80.  Others say 98.  Others say over 100.

One of those Missoula floods is thought to have been the biggest flood in world history.

The second biggest flood came from the other direction.  Lake Bonneville filled the Great Basin where Utah sits.  The Great Salt Lake is the remnant of Lake Bonneville.  The climate was wetter then.  There was no outlet to the basin.  The basin filled with water.  The water level was 1,000 feet higher than the current level of the Great Salt Lake.  Even to the untrained eye the ancient shorelines are plainly visible on the Wasatch Mountains above Salt Lake City and Ogden, Utah.

The lake continued filling, like a bathtub, until the water level reached the lowest point on its rim.  That low point was Red Rock Pass in southeastern Idaho.  Red Rock Pass was where two alluvial fans met that came down from their opposing mountains and filled the valley between them.  It made an effective dam, until Lake Bonneville overtopped it.  Just like with Missoula's glaciers, the alluvial dam simply melted with the force of the water that spilled from the lake.

It is thought that the lake discharged 15 million cubic feet per second, and did so for two weeks.  For comparison purposes the Columbia River has an average flow of 265,000 cubic feet per second.

The flood spilled into the Snake River and followed the river's course through Idaho.  It tore loose vast amounts of basalt rocks and tumbled them downstream, rounding them.  They were deposited in beds 300 feet deep.  These rocks are round, and are from three feet to 10 feet in diameter.  Geologists have named them “melon rocks” because they're shaped like watermelons.

The first time I went to Utah was in 1966.  I was fascinated by the advertising signs that the Stinker Station gas company had erected all along the way.  They were funny, and I kept watch for the next ones.  One said, “Grizzly bear feeding grounds:  Count your kids, hide your honey.”  Another was planted in the middle of one of these fields of melon rocks.  It said, “Petrified water melons:  Take one home to your mother-in-law.”

The first detailed account of the Bonneville Flood was published in 1968.  It described a flood crest 410 feet high coming down the Portneuf Valley above American Falls, Idaho at speeds up to 70 miles per hour.  This happened 14,300 years ago.  It was a one-time event.

At Tammany Bar south of Lewiston you can see the Bonneville Flood gravels overlying 20 layers of Missoula Flood gravels where the floods backed up the Snake River.  On top of the Bonneville gravels are about 21 more layers of Missoula Flood gravels.

These floods took place during the Ice Age when the climate was cooler and wetter than it is now.  The glaciers that covered Canada built up and receded over and over again.  So much water was tied up in glaciers that the ocean level is thought to have been 300 feet lower than it is now.

The Ice Age ended about 10,000 years ago, and we no longer need to worry about cataclysmic events from that source.

But Oregon has repeatedly experienced a different water cataclysm which is due to happen again.  Seventy to 100 miles off the coast of Oregon and Washington, and extending up into British Columbia and down into California is the 620-mile-long Cascadia Fault.  The Cascadia Fault is where the Juan de Fuca Plate meets the North American Plate.  At the fault line the Juan de Fuca Plate is diving under the North American Plate.  The entire surface of the earth sits on massive plates—and they're moving.

A German geologist by the name of Alfred Wegener in 1912 noticed that the west coast of Africa was a nice fit for the east coast of South America.  He did a lot of research, and determined that Africa and South America had once been joined.  He published his findings in 1915.

Like with J Harlan Bretz, other geologists laughed at him.  Everyone knew that giant land masses can't move.  J Harlan Bretz lived long enough to see his theories vindicated.  Alfred Wegener did not.  He died in 1930.  In the 1960s scientists began to understand plate tectonics.  Land masses are actually continually on the move.  They've even proven that not only is the Juan de Fuca Plate diving under the North American Plate, but that the entire Pacific Northwest is slowly rotating in a clockwise direction around a center point located at Pendleton, Oregon.

These earth movements are slow.  The two plates are locked together, and the movement causes tremendous pressure and stress to build.  On an average of about every 300 years the pressure on the Cascadia Fault gets released.  One plate takes a sudden dive, and the other is thrust up.  The result is an earthquake registering as high as 9.5 on the Richter Scale with an accompanying tsunami of gigantic proportions.  The Cascadia Fault produces mega earthquakes.  A 9.0 earthquake is 1000 times stronger than a 7.0 quake.

Geologists determined that a giant tsunami inundated the entire Pacific Coast in fairly recent times.  In several coastal areas there are ghost forests where dead trees are standing out in bays caused by a sudden subsidence of the earth.  By studying the growth rings of these trees, and comparing them to living trees, it was determined that the earthquake and tsunami occurred sometime just before or just after the year 1700.

No one on this side of the Pacific Ocean was keeping records then.  White men hadn't yet arrived here.  It wasn't until May 1792 that Captain Robert Gray first sailed into the mouth of the Columbia River.  He named it after his ship.  There weren't any American records to say when the tsunami happened, but on the other side of the Pacific the Japanese were keeping records.  A giant ghost wave of unknown origin hit Japan's shore in January 1700.  It was a mystery tsunami because there hadn't been an earthquake.  Calculating the speed at which a tsunami crosses the ocean (330 MPH) the date and time of the Cascadia earthquake was pinpointed.  It happened at 9:00 p.m. on 26 January 1700

An Indian legend says that everyone was asleep on a winter night in two villages on the Washington coast when the ground shook violently.  A short time later the ocean rose up and took one village away.  The other was higher above the water, and survived.

Oregon State University outfitted a research vessel which drills down into ocean sediments and brings up core samples that can be studied.  Each time the Cascadia Fault goes off it causes undersea landslides.  The ocean floor looks like above-water topography with steep hills and canyons.  By drilling down into these canyons where the landslides occurred, scientists are able to count and to date the landslides likely caused by the Cascadia Fault's earthquakes.  Evidence was found of at least 13 megaquakes occurring roughly every 300 years.

There is no danger of another Missoula or Bonneville Flood, but it has now been 323 years since the Cascadia Fault last went off.

Oregon needs to brace itself for the tsunami that is overdue.