Everybody Has a Story: Digging into volcanic history

In the summer of 1979 I was working as an equipment operator for the Gifford Pinchot National Forest road maintenance department, based out of the Willard Forest Engineering Work Center.

It was my third summer work season and I had become familiar with the required work, operating a backhoe and other equipment, cleaning roads of winter damage caused by snow melt, high water, downed trees and landslides, as well as making improvements to the roadways once they were opened for public travel. This was my main job at that time.

One day I was instructed to move the backhoe to a site on Forest Road 32 near Lone Butte Meadows for a meeting with an employee from the U.S. Geological Survey. He would instruct me as to what work needed to be done.

The person I met was Donal R. Mullineaux, a researcher investigating the history of eruptions of Mount St. Helens and other Northwest volcanos. He had selected this undisturbed, flat, open meadow that was close to the road so I could get the backhoe out where it was solid and dry and the machine would not sink into the mud.

It was a pleasant, sunny day, no sign of clouds. A perfect day to go time traveling.

After some delicate maneuvering to get the backhoe off the road and into the meadow, I lowered the stabilizers and front bucket and proceeded to dig a trench with the backhoe bucket — down one or two feet at a time, creating a vertical wall that Mullineaux could then clean off with a small trowel and collect samples into small containers. He made notations on each container about depth and the type of material being sampled.

It was obvious to the naked eye that there were layers or horizons of material — some granular, some larger and more porous — but it looked like the volcanic ash we all became familiar with when Mount St. Helens erupted in 1980. There were size and color differences between the layers, and organic material that looked matted and compressed.

As we got deeper into the ground I built some steps at one end of the pit so Mullineaux could get in and out of the trench as he worked. When we had dug about as deep as the backhoe could reach, I hit solid bed-rock, possibly an old lava flow. That was as deep as I could go.

Mullineaux was happy with the samples and I proceeded to backfill the pit.

He explained as we were digging that he was researching selected areas around Mount St. Helens for evidence of past eruptions and one way to do that was to go back in time to see what previous eruptions had deposited. This meadow was undisturbed and free of tree growth for centuries. It may have been a lake once. Any material from Mount St. Helens or other Northwest volcanoes would fall and settle here, creating a layer cake of undisturbed eruption history.

Mullineaux had co-authored a paper on predicting the possibility of the 1980 eruption with amazing detail. The paper was used in 1980 as a descriptive guide for government, media, law enforcement and first responders before and after the eruption. Our day’s work was an extension of his ongoing research.

After our work was done Mullineaux showed a nearby road cut where similar layers were exposed — except for one. There was a very deep layer, maybe 12-inches thick or more, that was deep brown and not the gray color of the Mount St. Helens ash. There was a black layer below the brown, with different types of ash layered in it. Mullineaux explained that the thick layer was from Mount Mazama, also know as Crater Lake, in southern Oregon. It was from a huge eruption many thousands of years earlier. The black layer was from forest fires the eruptions started before depositing the deep layer of brown ash and pumice stones. It was obvious that the eruption of Mount Mazama was a huge event for the Northwest.

When Mount St. Helens erupted a short year later and I got involved in the subsequent cleanup, I thought back to that day with Donal Mullineaux in the meadow, reading geology history and learning so much just by digging a trench.

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