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.

The Upsides and Downsides of Mountains

I’ve lived in Western Washington for a total of twenty-one years, so it’s really easy for me to answer this month’s Accretionary Wedge (#29!) as posed by Ann at Ann's Musings on Geology & Other Things: "What Geological features about the area you call 'home' do you love? and what do you not like?"

Washington can be divided very roughly into thirds: Eastern Washington, home to the Missoula Flood-carved Columbia River Flood Basalts; Western Washington, with thick glacial deposits and steep stratovolcanoes in the Cascade Mountains; and the Olympic Penninsula, which is an accretionary wedge, with the uplifted Olympic Mountains.

My favorite geological features are the volcanoes. These result from the subduction of the Juan de Fuca plate beneath the North American plate:

Cascades Volcano Observatory

Mt. Rainier

Mt. St. Helens

Mt. Adams

 

Now, my least favorite geological features of Western Washington are also the Cascades, because they help cause the massive, constant amounts of rain.

sequimwa.com

The Olympics create a rain shadow, but they aren’t so high that all the moisture condenses and falls: the rest is carried over the Puget Sound. As it does so, it picks up more moisture, which then condenses as it rises over the Cascades, dropping all over Western Washington.

That’s why it rains 365 days out of the year (or at least feels like it!)

Thus, my Theory of Seattle: the rain nourishes the trees and shrubbery, which grows profusely and blocks out the light. Between the rain and the trees, everyone wants to stay indoors – thus, the major IT industry begins. Between the masses of commuters and the nasty dim weather, rush hour runs rampant. Since everyone codes late into the night and has to get up early to beat the traffic, the immense coffee culture is started. Thus, the population has a Vitamin D deficiency, stares at computers constantly, is always struck in traffic, and gets regularly strung out on coffee, resulting in perpetual depression and tweakiness. Thus leading to the reign of 90s grunge music, which also contributes to the high suicide rate.

That’s my theory, at least. And I’m sticking to it.

I’ll be honest: I’ve had my fill of the dreary rain and endless rush hour.

So, I’m going to study Geology at Boise State University next year!

Boil, Boil, Toil and Trouble: Lava Cave Features

 

Lava tubes frequently show fantastic features, and I saw some really cool features while I was interning through the GeoCorps Program with the BLM at Craters of the Moon National Monument and Preserve. Some of the more decorative formations are the result of boiling gases inside the lava. Honestly, I hadn’t seen many of these formations before this internship, so it was very exciting!

It was interesting to learn more about lava: how the tube walls themselves cool, how secondary flows erode the original tube, how both cohesiveness and fluidity contribute to form features, and how the pressure in the flow creates different landscapes (like pressure ridges and tumuli.) Being able to observe a great quantity of lava over the course of three months was highly educational - even if I can’t cite lava facts of statistics, I know more about the characteristics of lava by seeing so much of it.

I know I haven’t given much information on the region’s geology itself, but that’s because I get too darned excited about lava tubes.

As the ceiling of a lava tube is cooling: first the exterior layers, and then the interior. Once the exterior layer has begun congealing, gases in the interior lava can boil, squeezing lava out through the exterior layers. (Kind of like a pasta machine.) As this lava drips down, the sides of the drip cool, leaving the liquid lava inside. This liquid lava can then flow to the bottom of the stalactite, creating a hollow space. Sometimes the last bit of the drip falls off the stalactite, other times it plugs the stalactite up. The left picture shows some stubby stalactites from Craters of the Moon, and the right picture shows some really delicate “soda straw” stalactites from near Mt. St. Helens.

If the lava inside these stalactites drips onto the ground, it can pile up to form a stalagmite. I didn’t see many in Idaho, but the ones I did see were really tall. Unfortunately, I didn’t have a camera that day, but I also saw some good ones in Bend this summer.

These are called “stalagpies” by the local cavers, but are more widely known as lava roses, especially when they have a clearly defined series of concentric rings. I think they look a bit gross, but they can form in a really nifty fashion: when lava boils from under a semi-cooled floor, the pressure of the gases pushes the lava up through the floor. As a result, these are also sometimes called “lava volcanoes.” These are identifiably by their “central conduit,” which can be easily seen in the bottom picture. These pictures are from a lava lake, so this explanation makes sense.

Because these don’t have a conduit, I think this is an example of the other way in which lava roses form: when larger clumps or sheets fall from the ceiling, and pile up, cooling, slumping, and cracking as they do so. (I think the right one is especially ugly – it resembles a miniature Horta.) These pictures are from a different cave than the previous lava roses – so a different origin is plausible.

These are lava helictites! These are created in a manner similar to the lava stalactites above, but the lava is pushed through weak spots in the developing crystal structure, forcing it into a twisted shape. Both lava and calcite helictites refuse to obey gravity.

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References:

If you want to learn more about lava caves and their features, here are some great resources:

The Virtual Lava Tube is an easily accessible resource, complete with beautiful pictures. This site is run by Dave Bunnell, editor of the National Speleological Society News. He also published the information in a book called Caves of Fire: Inside America's Lava Tubes, which is gorgeous.

Nomenclature of Lava Tube Features is an older article, but describes a greater number of features than the Virtual Lava Tube, including many different types of stalactites and pahoehoe lavas. It’s available in print form in the proceedings of the 6th International Symposium on Vulcanospeleology, and in illustrated form as An Illustrated Glossary of Lava Tube Features. (I wish I’d found the online copy earlier – I accidentally left my print copy in storage!)

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An aside: nothing I say on this blog represents the opinion of Craters of the Moon National Monument and Preserve, the BLM, the NPS, the Geological Society of America, GeoCorps, or the National Speleological Society and its internal organizations. I will not disclose any cave locations, but if you wish to go caving in Idaho, please visit Craters of the Moon National Monument (NPS,) the Shoshone Field Office (BLM),  or get in touch with your local caving club.

Mt. St. Helens Pictures

May 18th was the 30th anniversary of the 1980 eruption of Mt. St. Helens!

Mt. St. Helens erupted prior to my birth, and I actually only saw it once before I turned 16. But, since then, I've been trying to make up for lost time. Living within a few hours of it makes that pretty easy!
These pictures are all from within the last year.

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Memorial Day Weekend:

(I can't lie - this sign is always exciting!)

Still snow-covered.

Older flows contain the majority of Washington caves, including the ever-popular Ape Cave, open to tourists in the summer, and Gueller Ice Cave, a personal favorite.

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August:

Without the snow, it's much easier to see the effects of the devastation.

Immediately after the eruption, there were large chunks of the mountain's glacier interspersed with this material. When these melted, they left behind hummocks, or piles of volcanic debris, including ash and large blocks from the cryptodome (the bulge.) The orange coloration is from geothermal alerting before the eruption - as they were heated and exposed to heated water and gases, the chemistry was altered.

Here you can see two different types of lava that were being mixed together when they erupted.

Spirit Lake: Even to this day, there's a layer of logs on the surface of the lake. They float around the lake when the wind blows.

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September:

The wind picking up ash on the crater.

The lava domes! The old one is in the foreground, the new one in the background. Should you decide to climb Mt. St. Helens as a tourist, you'd hike up the back side, and summit at the crater wall seen in the background.

A concentrated pyroclastic density current near the crater, with hiking staff for scale.

Gas escape pipe in another pyroclastic flow. After the eruption, the gas that was in the flow needed a way to escape, and formed these pipes to the surface.

Spirit Lake, again, as seen from the Pumic Plain

Older uplifted flows

Pumice (with frog for scale)

This is a small hole dug into the pumice plain. You can see the layer of pyroclasic flow, with the pumice that was rafted to the top. Then, immediately on top is the layer of ash deposited from the ignimbrite cloud. (A layer of very fine ash that rose from the pyroclastic flow, then fell after the flow was deposited.)

Debris avalanche deposits are visible here, seen as the triangle of rising ground in the center. On May 18th, there was a 5.1 earthquake that released the largest landslide in history. This landslide released the pressure in the cryptodome, which trigged the eruption, and the pyroclastic flow. The pyroclastic flow traveled faster than the landslide (or debris avalanche) so the debris avalanche deposits are on top of the pyroclastic flow deposits.

When the pyroclastic flow overran a small lake, the water was flash boiled, creating an explosion pit. This one has been subsequently filled by water.

This is a sample of the dacite cryptodome from the 1980 eruption.

This is obviously my favorite.

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References: I learned most of this in the class I took last summer, and the brief fieldwork I did with that professor. They were both pretty awesome experiences!