Washington to Idaho Road Trip, Featuring Basalt

About two weeks ago, in May, my mother and I set off from her house in Seattle to travel to Idaho. I live (and now work!) in Idaho, but was back home to visit my brother and sister-in-law, who were in town for a spell (and newly expecting a baby!) This trip was held together tenuously from the beginning, and quickly began to disintegrate along the way. Luckily, we got to see some awesome stuff along the way.

Our first stop was Mt. St. Helens, always a favorite stop. I’ve never been here so early in the season, so I’ve never seen it so snowy! This iconic view from the Johnston Ridge Observatory really lets you look into the crater and see the lava domes (here, due to the snow, they look like a vague bump towards the back of the crater.) This spot also gives you a good look at the Pumice Plain, (the low area in the foreground) that consists of debris avalanche hummocks mostly covered in pyroclastic flows and ash fall deposits.

This is a nice outcrop near the Johnston Ridge Observatory, that really clearly demonstrates the layered nature of stratovolcanoes. You can see different lava flows (andesitic and basaltic) alternating with layers of ash and possibly pyroclastic flows (in this instance, I’m not sure which it is, or whether it is a combination of both.) All the different colors are a result of hydrothermal alteration on groundwater that seeps into the deposits, is heated by the still warm deposits, and encounters pockets of gas.

Once we left Portland, the cold my mother had been fighting off finally caught up to her. We stopped in a town called Cascade Locks for the night, slept in late the next morning, and then got some restorative chowder before heading out.

We took a short side trip off I-84 on an Oregon 30 between Mosier, OR and The Dalles, OR. When I was first moving to Idaho, we discovered this scenic jaunt, and it was great to see it again. Partway through, there’s an overlook of the Columbia River and the Columbia River Flood Basalts at a place called Rowena Crest.

The road down from the overlook is this delightful road called the Rowena Loops. It’s quite exciting (especially for one’s passengers!)

Somewhere along the highway near Pendleton, we pulled off the highway to look at this cool cement plant. After this, though, we encountered some pretty intense rain, and ended up staying in La Grande for a night.

Once we got to Boise and picked up my car, we joyfully discovered that it had some sort of gas leak. (This heap – I mean, jeep is beginning to get on my nerves.) We dropped it off at the shop, and drove into the foothills above Boise to camp. Along the way, we stopped at Diversion Dam. It was built in 1909 to supply water to another, older system of canals, to irrigate nearby farmland.

One of the cooler things about it was the logway – a special portion of the dam constructed to allow logs from logging upstream to pass through the dam. (The area upstream is the Boise National Forest)

It was interesting to see how the water from the less constricted logway (on the left) interacted with the water that was forced through the dam. Despite having an initially smaller outlet, the greater force enabled it to travel farther & spread out more before the turbulence achieved equilibrium. (I’m sure there’s a better way to phrase that, but my engineering-oriented physics class didn’t cover fluid dynamics… which is what I personally wanted to study! Someday maybe I’ll get to.)

We passed by several reservoirs, including this one. The differential erosion happening in the basalt here was really fascinating – the lower flow must be much harder, to have resisted so much more than the upper flow.

The road passed through areas of this potassium feldspar rich granite. The best exposures were alongside one of the dams, where the road was quite literally one lane carved into the cliffside, frequented by large trucks hauling boats. Needless to say, we didn’t really stop for picture taking.

When we finally began pitching our tent, we realized that the rainfly was still in Washington – and rain was predicted. My mum had this great idea to make one out of free garbage sacks and little bits of tape – which luckily worked pretty well, though it didn’t rain.

After that, we picked up my car (which luckily only had a leak in the fuel lines!) and checked the weather forecast. Since it was predicted to rain more and my mum was still under the weather, we decided to part company that day, instead of camping through the weekend. She headed west to Washington, and I headed east to my summer job. Much as a few days of mother-daughter camping would have been fun, it was nice to just call it quits and end the stress.