I made it down to California and back, where I was able to bring my samples to the big fancy machine that measures the helium 3 content in my rocks. I am running my samples at the Caltech Noble Gas Lab in Pasadena. First, I carefully weighed out approximately 500 milligrams of each sample into these little tins that will go into the machine.
I carefully rolled each sample into a tiny ball and organized them into this plastic container.
Next, they were carefully loaded into the mass spectrometer.
This machine goes through several steps to extract and measure the helium content in the samples. First, it heats them up to about 1400 degrees C, which is enough for the helium to be released from the rock grains. The gas that is released is pushed through a cryotrap, which is essentially an extremely cold piece of charcoal that will remove some excess gases that we are not interested in measuring (carbon dioxide and methane, for example). Next, the gas is forced into a very small volume so that it can be measured by the mass spectrometer. This machine is amazing because it can detect individual atoms of helium, allowing us to measure very small concentrations of helium.
Some of the first numbers came out a little strange, so we decided to isolate the chromite from the olivine to measure its concentration of helium as well. (Chromite is a different mineral and makes up about 5% of my samples.) This involves dissolving the olivine away, which requires a very strong chemical that is reactive enough to melt through glass. We used hydrofluoric acid, which is a very dangerous chemical that requires a great deal of care to handle in the lab. We simmered the samples in special Teflon bottles that are resistant to hydrofluoric acid. Slowly but surely, the olivine began to dissolve, leaving the chromite behind.
I do not have many numbers back since only a few sample runs have been completed, but hopefully I will get data back within the next month or so.
As every good grad student does at some point (or many times?), I spent the entirety of Labor Day weekend in the lab. I’m flying to California on Wednesday to (hopefully) run my samples at CalTech, and I needed to have them all prepped and ready to go by then.
My rock samples are primarily made up of three minerals: olivine, a type of pyroxene, and chromite. We are trying to measure helium 3 in the olivine, which is great because most of the dunite in the Twin Sisters is greater than 90% olivine. Because of this, we are not isolating the olivine from the other minerals. We are attempting to do this analysis with the whole rock. This first analysis might totally flop, however, and we may have to isolate the olivine. Separating these minerals is a difficult process (and also requires dangerous chemicals), so we are trying to avoid it if we can.
In order to go into the machine that will measure helium 3, my rocks need to be crushed up to a very specific grain size. I began by smashing my larger rock samples into smaller chunks, which I then fed into this “Jaw Crusher,” also known as the “Chipmunk.”
The rocks have to be smaller than two inches in diameter to go into this machine. They banged around, and came out the bottom like this:
Next, I fed these smaller rock chunks into a disc crusher, which makes the rock chunks even smaller.
The disc crusher looks like this on the inside, when you pull it apart to clean:
Once assembled, the two round plates face each other, and you can move them towards each other or farther apart to adjust the maximum grain size. When the machine is on, the discs spin against each other, crushing up the rock bits and only allowing them to fall into the tray below once they are small enough to fit through the gap.
The resulting pile of sand is composed of a mix of grain sizes from about 500 microns all the way down to dust.
I wanted to eliminate the dust, because dust particles can stick to larger grains and throw off the analysis. My next step was to wash the samples in water, pouring off suspended dust grains. The result is a dust-free cup of wet sand for each sample:
Wet sand is no good for analysis, so these samples needed to be dried overnight in a drying oven. I kept the temperature below 110 degrees C, to avoid cooking off the helium 3 in the rock grains.
The next day, the samples were dry again, and I could move on to separating out useful grain sizes. Target grain size for measuring helium 3 is somewhere between 150 microns and 500 microns. Above that, it is difficult to measure, and below that, you start to smash extra helium from the atmosphere into the grain when it is crushed. I separated my samples into two different fractions: 150-500 microns, and less than 150 microns. I did this by using a 150 micron sieve (like a screen with tiny holes). The smaller grains fall to the bottom, and the larger grains stay on top.
Finally, I poured the larger grain fraction (the portion we are interested in measuring) into vials for traveling. I kept the smaller grain fraction too, just in case, and poured that into a ziploc bag.
I just finished this afternoon! It took almost 3 full days of tedious work in the lab, but now all of my precious samples are neatly organized and ready for travel.
I cannot believe that it is finished. I am happy to be done, because it means I can move forward with my research, but I already miss being there. The smoke from wildfires in British Columbia cleared for this trip, so our views were absolutely spectacular.
We began our trip by hiking up to the spot where we camped last time, at the base of the cliff, surrounded by waterfalls. It was amazing to see that the streamflow was way down from just a few weeks prior, evidence that snowmelt has been slowing down. Some of the little channels that we hopped through a few weeks ago were completely dry.
I found an excellent flat rock for cooking, which pleased me greatly. Crouching on the ground to cook gets really old after several days in the backcountry.
The next morning, we slept in and then watched the solar eclipse. I tried to take photos, but they all turned out blurry. The sun got to be about 90% covered by the moon. It was difficult to notice a change in the light, but we did notice that it got really cold. The light turned sort of golden, like it does at dawn and dusk. I regret that I did not get any candid photos of us with our fashionable eclipse glasses.
Around midday, we packed up camp and scrambled up 1,000 vertical feet in just three-quarters of a mile to our base camp. We stayed in a little cirque very near our sample collection area.
Words cannot describe how perfect this campsite was. There was not only one, but several flat cooking rocks to choose from. Our water came fresh from a snowfield, and there was an abundance of flat tent sites. The snowfield also doubled as a great butt-sliding sledding hill. To top it all off, we were surrounded by pikas, darting about the rocky slopes around us.
If you’ve never seen or heard a pika, they make the cutestsounds, and they look like this:
These little cuties serenaded us every evening as we were getting ready for bed. Pikas are actually members of the rabbit family, not rodents at all. They live on rocky alpine slopes, and require cold temperatures to not overheat. They gather stockpiles of grasses in the summertime to feed on during the winter. I also recently learned that they digest their food twice: once when they eat the grass fresh, and once again after it comes out the other end (read: they eat their own poop!).
On one of our nights there, I attempted to take photos of the stars, which were stunning. This was my first attempt, and the results were mediocre at best.
The next morning, we gathered our research gear and set off to begin sample collection. It was absolutely amazing up there. Evidence of past glaciation was everywhere. I have never seen so much glacial polish in my life. This happens when glacial ice scrapes over the top of bedrock, smoothing the surface like sandpaper. It also leaves striations, which are lines oriented in the direction of ice flow. Small rocks embedded in the base of the glacier carve these lines as the ice flows.
The whole slope below the modern glacier was amazing to explore. Glaciers generally erode through a combination of abrasion (when it scrapes like sandpaper, as above), and plucking (when large chunks of bedrock are removed all at once). This combination of erosional styles results in lumpy topography, with smooth mounds of bedrock and deep pits, often with flowing meltwater. We scrambled up steep mounds, smoothed our fingers over polished rock, and hopped over narrow meltwater streams.
Eventually, we located ourselves on the Lidar image and began collecting rock samples up one of our transects.
The samples were surprisingly easy to extract, thanks to fractures already present in the bedrock.
At each sample site, we recorded location and elevation, and measured the sample thickness, degree of oxidation, and angle to horizon, which will help me calculate to what degree the sample was shielded from cosmic rays by the surrounding topography.
We bagged each sample with a strong ziploc bag, wrote the sample number on the outside of the bag in sharpie, and put a notecard with the sample number inside the bag in case the outside number rubbed off.
We returned to camp late that afternoon to find that my advisor Doug had arrived, accompanied by his very cute dog, Cinder. A little dog time made me very happy. Both of them accompanied us the next day to explore and collect more samples.
We walked all the way up to the modern glacier that day. It was my first time up close and personal with glacial ice.
I even got to eat a chunk!
I loved checking out crevasses on the ice, and we could hear water from subglacial channels flowing below.
We crossed beautiful late-summer snowfields up near the glacier.
We also found potholes, which are round holes carved in the bedrock when subglacial meltwater under high pressure spins a rock around, drilling a hole into the bedrock.
Also, subglacial fluvial (water) channels, which form in a similar process. This time, the water flows down the channel carrying rocks and debris, and the high-pressure conditions form this very rounded, straight channel:
Here are all of us during our lunch break:
Doug went back home the next morning, and the rest of us finished our sample collection. We ended up with 28 samples total on this trip, plus six from the previous trip. This map shows all of our sample locations (Lidar image in the background), with sample numbers:
This next image has our GPS tracks, showing all of the places we walked. The blue triangle shows our campsite, and the blue dots are our sample sites. The orange track is our first day, the red track is our second day with Doug, and the purple track is our final sample collection day.
A final discovery that we made was a vein of some type of rock that was not dunite (!!!). It popped up twice, along what I perceived to be the largest fractures in the area:
I have yet to determine what this mysterious grey rock is, but I brought a chunk home with me to check it out.
We took one last group photo on our way out.
I cannot thank these three enough for all of their help! They were wonderful field assistants, thoughtful, efficient, self-directed, and always positive (even when getting stung by a bee, sliding down steep rocky slopes, or pushing through thick, woody brush). Your support was invaluable to me!
Next step: figure out how to get my samples processed!
I cannot tell you how excited I am to get back out to the Twin Sisters. Annalise and I packed up all of the food today, and we will be heading out early on Sunday morning. Hopefully, we will make it up to our previous campsite on the flat gravel bar. The eclipse is on Monday morning, so we plan on taking a slow morning to watch it happen (don’t worry, we’ve got eclipse glasses!) and then head up to the small cirque to make camp closer to where we’ll be collecting samples. If all goes as planned, it should take us only three days to collect all of the samples that we need once we get up there. However, field work usually does not go as planned, so we have enough food for nine days total just in case.
I am very excited about a recent technology discovery that I have made! I got a solar charging device, which means that I can use my phone as a camera in the field and won’t have to worry about the battery running out. I have also discovered a free app called “Avenza Maps.” This app allows me to view my own custom maps on my phone screen AND it functions as a GPS, even without phone service. This means that I can view my Lidar data on my phone, and find my location very easily and accurately! I have also uploaded a basic USGS topographic map to the app. This is a fantastic discovery because I was considering purchasing very expensive GIS software to use on an iPad for this exact purpose, and this is completely free! Here’s a screenshot of my Lidar map that I can view on my phone screen. When I’m there, it will show my location too:
We have returned safely from our trip up to the Sisters Glacier. This is one of the most amazing places I have ever been. I have a lot to say, so I’ll start at the beginning.
We parked the car in the morning, and began our trek up the Sisters Creek. We had wet feet, but the cold water felt good in the summer heat. We climbed over and ducked under log jams, and eventually had to leave the stream when it became impassable. We passed the recon trip campsite, and pushed further upstream. Around mid-afternoon, we set up camp on a gravel bar next to the stream. We did not want to continue further, because the grade steepened quickly, and we did not know if we would be able to find a flat spot to pitch our tents before dark.
The next day, we packed up camp and climbed further upstream. The stream started to get steep and full of rapids, making travel difficult, and thick vegetation on the side of the stream was also difficult to walk through. Luckily, we stumbled upon a dried-up stream bed that we were able to follow up the slope, which eventually led us to scree fields, all the way to the area where we expected to camp. We climbed up 1,500 feet, and the going was very difficult with heavy backpacks full of camping and research gear. We were rewarded with a spectacular view of the cliff below the Sisters Glacier, as well as gorgeous alpine meadows.
We found a lovely spot to camp on a gravel bar in the braided channel.
The next day, we packed up our lunch and research gear and bushwhacked in the forest near our campsite to collect some rock samples. The purpose of these samples is to gather an exposure age for the whole valley, or to measure the amount of time that this area has been free of glacial ice. This will help strengthen the argument when we collect samples from higher up.
Annalise and Anthony were very helpful field assistants! Together, we chiseled out six rock samples. Here’s Anthony hammering out our first sample:
Here’s both of them with our first sample! #proud
Some of the samples were well-exposed and easy to extract, and others were much more difficult. We hammered at this one for about 45 minutes, and ended up with several pieces.
There was one small hiccup in our day: while we were bushwhacking, I accidentally bumped a hornet’s nest. I scampered away as quickly as possible, but I got stung on my left leg. Cold rocks from the stream helped, thank goodness for glacial meltwater.
We had lunch by the stream, and there were some amazing fluvial features carved into the bedrock!
Here are all six samples that we collected!
It was very warm outside, so we walked up to one of the waterfalls coming off of the cliff to cool off. It felt amazing, and it was gorgeous!
The waterfall was too tall to capture in one image.
We headed back to camp, and had some delicious backcountry pizza, served on a beautiful Lidar map.
Our task for the next day was to figure out how to safely get up the cliff to access the majority of our sample sites. The original plan was to scramble up this ramp that was visible on topo maps and on Google Earth. It seemed like a good bet from a distance.
Unfortunately, but not to anyone’s surprise, this route turned out to be quite sketchy. The slope angle wasn’t a problem, but waterfalls and streams crisscrossing the ramp were very slippery.
I didn’t take many pictures on the way up, because I was too busy focusing on finding a safe route. I didn’t feel unsafe at any point, but this route would not be fun or sensible with a heavy backpack. We made it to the top, but were apprehensive about the possibility of needing to go down the same way.
Being up there was SO COOL. There were glacial striations all over the place. I was geeking out so hard. We all were. Here we are, posing in front of some beautiful striations that you can’t really see because of the camera angle.
Here’s a better photo of some of the striations:
We ended up finding a MUCH safer route down, and will not be attempting the sketchy route again.
This route led us to a beautiful bowl, where we hope to camp in the future. We also found mountain goat bones. So cool!
We scrambled up to a high point, where we got an outstanding view of the glacier. Wildfire smoke from British Columbia made the view a bit hazy, but stunning nonetheless.
And there were adorable wildflowers!
That evening, we noticed a strange object flying through the air above the glacier. We watched it come over the mountain, and descend down the slope towards our campsite. As it got closer, we recognized it as a bundle of balloons! Don’t lose your balloons, kids, they’ll end up littering a pristine wilderness area.
By that evening, my hornet sting got much worse. It was swollen, warm, and covering most of my thigh. I took some benadryl, and hoped that it would improve by the morning. Unfortunately, it only got bigger overnight, so we decided to head out the next morning. I didn’t think it would be good to spend another day out in the sun with a swollen, painful insect sting. Oh, the joys of field work! I was sad to leave a day early, but knew that it was the best choice. I stashed some of the heavy field gear in the woods, and marked it on the GPS to be picked up when we return the next time. We made it all the way back to the car in 6.5 hours. The going was much easier, now that we had found a suitable route. Here is a map of our travels throughout the trip:
Overall, I had a fabulous time, and I am very excited to go back soon!
I’m headed back out on Thursday, with my two field assistants Anthony and Annalise. I spent all afternoon today organizing and packing food, because it drives me crazy when food is disorganized in the field. The two biggest struggles for me when packing food for backpacking are: keeping the weight down, and making sure we get enough vegetables. I recently discovered the magic of freeze dried and/or dried vegetables, and purchased a bunch of these online:
The best part about these is that they don’t spoil, and they’re light and compact! The freeze-dried vegetables weigh almost nothing. All it takes is dropping them into boiled water, and they’re almost as good as fresh.
I also discovered powdered dairy products: another amazing backpacking food.
These are excellent when added to meals such as macaroni and cheese, pancakes, and lentil curry. My favorite discovery is the egg powder, which is actually delicious. I’ve planned two breakfasts of eggs for this trip. Just add water, fry them up, add some salt, pepper, and dried veggies, and you’ve got a delicious omelette. Such a luxury to have eggs in the field.
All of the food gets packed into Ursacks, which are bear-proof stuff sacks.
These bags are made of super strong canvas, and have been tested to withstand the claws and teeth of grizzly bears. More likely, they will keep out pesky little rodents. The nice thing about these bags is that they are lighter than bear canisters, and do not require hanging up in a tree. Just need to tie them up so the bear can’t steal it.
Hopefully seven days will be enough to travel up to my field site, collect samples, do field mapping, and assess the access points for the glacial forefield. I’m looking forward to it!
The trip definitely did not go as planned. Walking up the stream was not safe much of the time, and in many places, huge logs jams made it impossible.
This forced us into the forest, where dense undergrowth and a labyrinth of fallen logs made travel very difficult. After an exhausting day of travel, we ended up making camp about 1.5 miles up the stream from where we parked. The GPS track, however, showed that we actually walked much farther than that to get there.
The red line shows our route upstream on Tuesday, and the blue line shows our route downstream on Wednesday. We decided to turn around early because there was no way we were going to be able to get to our destination with the time and food that we had. Here’s our route relative to where we expected to get to:
The green tent symbols represent potential camping locations. As you can see, it took us a whole day just to get half-way there. We did, surprisingly, run into some evidence of human activity. At the blue flag marked “Wilderness Sign,” there was a sign marking the boundary between the National Forest and DNR land. We also found pink flagging tape tied to trees, which we thought for a while might be marking a trail, but it turned out to mark a timber sale boundary.
On the bright side, this area was beyond gorgeous. Our camping spot was idyllic in my opinion, and I had a good time snapping some shots of pretty flowers after dinner.
It still floors me that the whole stream was full of dunite pebbles. Dunite everywhere! Nothing but dunite!
We got a peek of the glacier from our campsite:
This is how I felt upon returning to the car yesterday:
…and this is the damage done by mama nature. Please note that my pants were soaked up through my underwear.
Oof. Field work is challenging. My plan for now is to make another longer trip up there next week, and go from there.
The gate key that I got from the logging company didn’t work on any of the padlocks at the gate that I needed to get through. Venice and I spent 6 hours driving around, talking to random people, and trying to figure out the problem. Turns out that there’s a different kind of padlock than they had on record. Anyways, I’ve got two different keys to try now, and Venice and I will make a second attempt tomorrow.
My wonderful friend Venice has agreed to accompany me in the field for three days! We will head out tomorrow morning, and plan on returning on Wednesday. I’m very excited! I will post updates when I return.
The person who was going to go with me this weekend is not feeling well, and I will not be going alone, so the trip is postponed. It looks like I have a couple friends who are able to go next week, though. Updates soon!