Mt. Hood

Had to take a trip down the Gorge a few weeks ago. Got this nice view of Mt Hood and the lenticular cloud above it.

Cascade Volcanoes in Spring

We haven't had a lot of time to do geology lately, Sam has been busy playing softball, and in general we have had a typical rainy spring. 

However last weekend we had a gorgeous two days, and as luck would have it, Sam's team played a tournament in central OR. On the trip down Friday night, we had clear shots of Mt. Hood in Silhouette above the Gorge,

Looking west at Mt. Hood down the Columbia George at about sunset

Sunday, I got up early to enjoy a little walk along the Deschutes River Canyon, and I was treated to show as the sun rose, casting its light on Mt. Jefferson.

Mt. Jefferson from near Cline Falls State Park

It was a gorgeous weekend, and Sam's team won the tournament.

Fort Rock

On the way home from Crater Lake, we drove through Southern Oregon. My primary purpose was to stop at Fort Rock State Natural Area.

Fort Rock is a volcanic tuff ring that stands about 200 feet above the surrounding paleolake bed. It is a near circular ring of lapilli tuff that is the result of a Surtseyan eruption 50-100 ka. Most of the larger clasts in the tuff are welded glasses and pumice

But in some places small basalt bombs are included too

Subsequent weathering by wave action created an opening on the south side of the ring, so you can hike inside the ~1 mile wide crater. Where the waves interacted with the structure, along the outside and along the cut, there is a visible bench. At other tuff rings in the area, these benches show evidence of human habitation 9-10 ka

Bench on edge of Opening

After Fort Rock, we cruised through the desert high plains of the Christmas Valley and into Burns, where we turned north to home. We were all ready to be home, so we didn't stop to geologize along the way, just a reason to go back and explore again.

More Summer Trips

Ok, so its been a while since I have been able to sit down finish posting about our trips last summer. After our trip to Sumpter/John Day, we spent a week at the coast. Most of our time at the coast was spent playing in tide pools and seeing non-geology things, but I did take one picture of some barchan dunes on the beach below the Yaquina Bay Lighthouse.

On the trip back to the east side of the state, we took the scenic detour through the desert high plains. This allowed us a stop at Crater Lake, which Sam had been wanting to go see ever since we moved to Oregon.

Stanton at the Rim near the North Entrance

We got to the park about 1 hour to late to take the boat ride (next time Sam) so we did the obligatory drive around the lake. Sam's favorite stops was at Pinnacles, where the steam from fumaroles welded together the overlying pumice and ash into an erosion resistant hoodoo.

On the way back from Pinnacles, we stopped at the new trail in the park, a 2.5 mile out and back to Plaikni Falls. It was a nice little trail through the woods, and the falls at the end were a nice surprise (ok I knew there was a waterfall, but it was more impressive that I had anticipated). Sam, however was tired, so by the time we got to the falls she had transformed into a bit of a sullen teenager.

Plaikni Falls

I think overall, Sam was a little disappointed in the lake. (I found out later that, being who she is, what she really had wanted to do was go swimming in the Lake. She didn't expect only one access to the lake that was 2-3 miles down a steep trail to a non-existent beach that would have been hypothermia inducing cold at that rate!)

Mt Baker

In my previous post, I mentioned that on a Rodeo Holiday we went up to Heather Meadows on the Mt. Baker Highway. While we were there, we ran into a High School Geology class and the instructor pointed out to me that even though we couldn't see any mountains, there was some notable geology under foot.

Basically the canyon that forms drains Bagley Lake is a fault. On the west side of the lake is the Chilliwack River Terrane an accreted island arc, and on the east side are Mt. Baker Andesites. The Bagley Lakes trail parallels this drainage and crosses over a small dam, where you can see the difference in rocks from one side to the other.


Sam Looking at Mt. Baker Andesites



Sam Looking at Chilliwack Terrrane

  According to the USGS website on the Chilliwack Terrain, it is mostly phyllites and Greenstones that are thrust over the younger Nooksack Terrane.


From: Terranes of the North Cascades: Chilliwack River Terrane

We saw a couple of nice metamorphic rocks on our hike. Admittedly the weather wasn't conducive to finding the best examples (and I am not great at identifying metamorphic rocks), but there were three areas that had distinctly different outcrops



Greenstone with quarts veins

 

Metaconglomerate

 

Not sure with this one, originally thought it was a different metaconglomerate, but then thought about a fault Breccia, didn't know if that made sense. Help?

Though I certainly saw the difference between the rocks, I was in "Look at the Mountain and Glacial Features mode" so I'm not sure if I would have put together the drainage was a contact between terranes. So thank you to the unnamed HS teacher I met. It certainly made more sense to look at rocks than mountains on that foggy day.

Pacific Northwest NAGT #3 Diamond Craters

The Pacific Northwest NAGT meeting was supposed to have 4 days of field trips, and one day (Saturday) of meetings. This years meeting only had about a 1/2 day of meetings so Saturday afternoon we headed out to Diamond Craters,, BLM designated "Outstanding Natural Area". Diamond craters began erupting about 20 ka and according to the the Global Volcanism Program website was last active about 7 ka. But according to our guide, there may be indications of eruptive activity in archeological sites that are less than 500 years old. 

  

From the ORE BIN vol 26 No 2, Feb 1964 

Unfortunately time was limited so we were only able to make three stops in the area, but each stop represented a different kind of volcanism so it was a great overview of the eruptive history: The first stop was a pair of Maars at the western end of the road. The first was smaller and dry, but the second (Malheur Maar) was deep with an active mosquito breeding farm at the bottom.

Maars/craters are generally caused by the ejection of hot steam and other volcanic gasses. The pressure of these gasses blow a hole in the surface that becomes the crater, but the eruption containes little to know magmatic material. So at our second stop we saw an eruptive area that showed indications of fountaines of eruptive matieral. Red Crater was a lapilli crater built up to about a hundred feet on the eastern side. The rim was comprised of lapilli sized tephra that had fused while still molten. Scattered around the site were a number of "Breadcrust Bombs". Volcanic Bombs that were beginning to cool and harden on the outside while still molten and outgassing on the inside. The release of the internal gasses cause the bombs to continue to expand, stretching the outercrust creating cracks like a crust of baked bread. This bomb was found about 50 feet from the crater rim.

Our last stop was Lava Pit Craters. Actually three craters formed by drained Lava lakes. Eminating from each lake are a sereies of tubes and caves of highly basaltic lava. 

One of the pits has a large cave/tube with lavacicles hanging down and a hornito on top.

 

 

Unfortunately because our time was limited, we did not make the hike into the central vent area with more than 30 vents and some "dribblet spires" where smalll amounts of molten lava is forced to the surface with just enough energy to run down the sides as it cools. Sort of like the magma version of a drip sand castle.  Oh well, it gives me a reason to make the drive back. 

Sam's Science Chat

In science we have a thing everyday called "interesting science fact of the day." this week all of them are based either on electricity or lightning which technically speaking are the same. Even tho lightning bolts have electricity the charge is brief so you couldn't use it to have a reading lamp on for thirty minutes. Lightning is an electric current ( electric current is the continuous flow of electrons within a conductor.) Within a thundercloud, many small bits of ice bump into each other as they swirl around in the air. All those collisions create an electrical charge. After a while, the whole cloud fills up with electrical charges (usually with a negative charge closest to the earth). Since opposites attract each other, that causes a positive charge to build up on the ground beneath the cloud. The ground's electrical charge concentrates around anything that sticks up, such as mountains, lone trees, people, or even blades of grass. The charge streaming up from these points eventually connects with a charge reaching down from the clouds, and--zap!--lightning strikes.

Have you guys heard of the Chaiten Volcano in southern Chile that erupted on Sep. 22, 2008 if not please click the date erupted and you will find a article. This volcano has lightning in its ash cloud.

I went on to google.com to see why there is lightning in a ash cloud and I found this on answers.yahoo.com they had what they called "the best answer" which is this...
The same process that goes on in any thunderstorm, rising turbulent warmer air causing static charges because of friction in the air, is being artificially created around the warm rising turbulent air from an eruption. Not only is ash rising, but huge amounts of hot water vapor is released as well. As the water vapor cools in the upper atmosphere, not only do you get lightning and thunder, but it also is likely to rain heavily which makes the ash fall even worse when it falls on top of buildings, by adding a lot of water weight to the ash. I saw a documentary on Mount Pinatubo in the Philippines recently on National Geographic and they showed the whole process. This only happens when there is a violent eruption. The low, slow flow like that in Hawaii does not cause any local weather effect as a violent explosive eruption does.
So that is a little bit about lighting and volcanoes.