Editor’s note: The author is a sophomore at Ocosta Junior/Senior High School and was part of a group from the school that accompanied Dr. Brian Atwater, a University of Washington professor and expert on earthquakes and tsunamis, on a kayaking trip on Johns River recently. Atwater showed them geological evidence of a 9.0 earthquake and resulting tsunami that traveled through the Johns River area on Jan. 26, 1700.
Seven lucky Ocosta Junior/Senior High School students recently got to go kayaking to see firsthand the evidence of a monumental earthquake that lowered the land, causing a tsunami to come through our local area. Dr. Brian Atwater showed us how the tsunami killed off the western red cedar population, only leaving a few snags as evidence today.
Using layers of dirt, he showed us a layer of sand that gave clues to a tsunami. All along the river bank you can see dead spruce roots protruding some three feet toward the river. He painted a picture in our minds and guided us to solve the mystery of this huge natural disaster.
There is evidence that a tsunami traveled through Johns River on Jan. 26, 1700, after a 9.0 earthquake lowered the land in the south beach area. Students were given the rare opportunity to see the proof of this tsunami along the banks of Johns River in Ocosta with a world-class University of Washington researcher as their guide.
In the early morning on March 4, Dr. Atwater took a group of students and teachers kayaking down Johns River. He is world famous for tsunami research, having studied in Alaska, Chile and Japan. He won the Kirk Bryan award from the Geological Society of America for his research on great earthquakes in Washington state. He has written both a public safety booklet on surviving a tsunami and a book on earthquakes. In 2005 he was named one of the top 100 most interesting people in Time magazine.
Atwater, accompanied by two other geological researchers, Sally Holt and Gene Woodwick, led the students to different sites on Johns River. These sites prove that a tsunami wiped out the western red cedar population in the South Beach area.
The adventure started with some tromping through ankle deep mud to get the water craft in the river. Each member on the adventure was given a keyed map showing significant sites to be visited. After all safety concerns were addressed and basic navigating techniques covered, the flotilla was off. First up was a trek across a boggy area to a dead western red cedar tree, known as a snag. The group was asked to observe many details, including the lack of any living cedar in the area, lack of bark and decaying layer on the outer part of the snag and it was also asked to look at a hole that showed the depth of the roots of the snag.
Dr. Atwater then pulled out a core sample taken from a nearby snag and explained it had been studied by scientists who compared ring patterns in the wood. They concluded that the tree lived through the year 1699 and then died. He explained that we had no written record of that time period and compared notes with Japanese scientists who had recorded a tsunami event on their shores on Jan. 26, 1700. We returned to the river to see more of the story.
Traveling north, down the river, Dr. Atwater stopped the group and dug into the bank about 3.5 feet and everyone observed a very dark line a couple inches thick. Furthermore, there was a line of big thick Sitka spruce roots at that same level. The puzzle was getting clearer. With more sophisticated evidence discussed, including carbon dating and plate tectonics, the conclusions were drawn. There was a massive earthquake exceeding 9 on the Richter scale on Jan. 26, 1700. On that day, the entire plate along our course slipped and the ground level sunk about 3.5 feet. The forest floor sunk to a level that had too much salt in it for the trees to survive. All of the spruce trees died, as did the cedar. As the layers of silt covered the ground with each new tide and rain, new spruce seedling survived in places, but not cedar. The story was somewhat complete.
On the last stop, the group stopped in view of the Ocean Spray plant and dug into a layer exposed by a sloughing off of the bank. The digging exposed beach sand. The exposed layer was consistent with the 3.5 foot depth of the sunken land. This final stop ended the amazing trek down the river. It is doubtful anyone on the adventure will see the area in the same light again.
The visualization of an event of that magnitude is certainly more vivid.