Field work: Week 2

This past week Jen and I headed back out to the Walla Walla Basin, but primarily for another project: doing the quarterly water level check and data collection download at observation wells in the Umatilla and Walla Walla watersheds. In between monitoring wells we collected the five remaining samples budgeted for the geochemistry project.

After visiting 60 or so wells, each with their standard blue wood-and-aluminum housing, they started to blur together. A few things stood out…

Cozy mouse nests and resident spidersimg_20180709_135009456

Granite boulders 200 miles from where they ought to be


and the earth-shaking exploding munitions that I was discouraged from photographing.

Those munitions were on the Umatilla Army Chemical Depot, where OWRD has a handful of  monitoring wells. Atlas Obscura has an intro and some interesting photos… The site was created during WWII to store weapons and supplies, and since then has been the location for disarmament from weapons stockpiled for use in the Pacific theater of the second World War as well as the Cold War. Our guide said that they had indeed gotten rid of all the chemical weapons stored onsite, and the current mission on the base is making sure that the old explosive weapon destruction pits are done exploding. That explosion while we were sampling was proof that the second look was necessary. The end goal for the site is to render it harmless enough for limited non-military use such as stock grazing.

Not much explanation is needed for the well housing tenants – the structures form hospitable shelters in the middle of wide-open grain fields. A perfect bed-and-breakfast for four-legged or eight-legged creatures. Luckily we didn’t see any of the region’s black widow spiders – just harmless, fuzzy Phidippus audax. For the sake of my arachnophobe friends I won’t post a portrait, but google them if you’re curious. They’re actually kind of cute.

That granite boulder, on the other hand, is a long way from home. Like, 100 to 200 miles. And it’s not a small boulder – it’s about the size of an oven.  Below is a map showing the “closest” granite outcrops in purple, and the location of this lonesome rock with a pink star. What on earth is it doing by a well in Morrow County, Oregon?

pnw granite and erratic

Like so many geological oddities in the Columbia River basin, it hitched a ride on the epic Glacial Lake Missoula floods (shown in blue below)! It likely came from somewhere around Spokane.

pnw granite erratic with floods

Glacial flood extent created by ESRI user jcleveland0, accessed via ESRI Online. Granite outcrops selected from the USGS Preliminary Integrated Geologic Map Databases of the United States shapefiles for OR, WA, MT, ID.

The Missoula Floods were an amazing manifestation of the latest Ice Age between 13,000 and 15,000 radiocarbon years ago. An ice sheet repeatedly dammed a predecessor of the Salmon river at its headwaters in Montana, creating a lake over 200 miles long. Then as water likes to do it eventually blasted through. Again. And again. In each flood event water racing at over 10 million cubic meters per second scoured the landscape in northern Idaho, Eastern Washington, and northern Oregon. These floods meant business, creating ripple marks bigger than houses, amphitheater-sized waterfalls, and topsoil stripped from Spokane to be deposited in Salem. That flow picked up boulders the size of buses only to set them down them hundreds of miles away, so the moderately sized one we saw on our rounds would have been a piece of cake.

The Washington Geologic Survey created a beautiful, user-friendly introductory website for the floods here. I really recommend it! It not only shows the scientific knowledge surrounding the floods, but the process of science that connected all the disparate observations into one phenomenal story. At least, phenomenal if you’re as nerdy as I am.

Our own research for the week was unfortunately nowhere as riveting as this rock’s journey. In the coming weeks I’ll wait with bated breath for the laboratory results, learn how to process four months of water level transducer data for a few dozen wells, and start my literature review. However any blockbuster geologic story like the Missoula floods was assembled out of thousands of seemingly trivial observations, so I’m happy to work away in my own little corner of science.


It’s not a bad-looking corner at all, just a bit hot…

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