Black Rapids: August 27-29

Posted by lwpetersen | September 29, 2012 | field work

The last week of August we returned to Black Rapids for the last time this season. The purpose of this trip was to winterize the 3 continuous gps stations and disconnect their solar panels. Soon there will be almost no Sun in this part of the world, so they won’t do much good anyway. We also removed the 4 seasonal gps stations, removed the batteries from three time-lapse cameras, and measured the locations of a few mass-balance stakes so that we can estimate the velocities further upstream on the glacier where there are no gps stations.

Since it is nearing winter on the glacier, we had to travel by helicopter so that we could land in a variety of different conditions. This was my first time in a helicopter and I’ll say that it was quite fun. Not only fun, but really efficient. We could land almost on top of every site we needed to visit. I would probably use them all the time if they weren’t so expensive.

Here are a few pictures:

On the first day we had rain. A lot of rain. It was one of those relentless rains, when you wake up and it’s raining and you just know that it’s not going to stop all day. Around noon we decided that we at least needed to make an attempt to get out to some sites. But, we were turned back about 15 miles up the valley where the cloud ceiling met glacier ice.

falls to black rapidsBlue water near the terminus

rough terrainthe delta river

This is the view of the Black Rapids Valley from the Richardson Highway. Most visitors to the area will never see more than this. Except for a tiny bit of bare ice showing, it’s hard to tell that there is even a glacier there. It doesn’t look much different from any other valley – maybe just a characteristic U-shape of a glacier carved valley (as opposed to the water-formed V-shape valley). In the foreground of this shot, and the above right photo you can see the Delta River, which blocks any easy attempt at a hike up the valley. You can ski over it in the winter, or pack-raft across in the summer, but it’s way easier to fly over. If travelling by foot, once across the river you still have a few miles to hike up the valley and then some pretty gnarly terrain to cross once on the glacier (pictures below). I’m hoping to be able to ski it, maybe this winter/spring, but I don’t know if I’ll ever make a summer attempt.

Alright, we’re almost to the interesting part . . . but first look at what we awoke to on the second day:

the clouds are lifting - they left something behind
winter is coming

Snow! Lot’s of snow on August 28th and not even at a very high elevation. The weather wasn’t looking much better, but once again, at about noon we gave it another shot.

Here is a view of the Delta Valley to the south from the air. The Richardson Highway runs on the west side (left) of the river. That giant mound is one of the terminal moraines from previous surge on the Black Rapids Glacier. I believe this is from the 1937 surge. During a surge the glacier can move hundreds of times faster than normal for months at a time. This usually means that the glacier advances quite a bit. After it stops surging it leaves behind lots of debris that was pushed and carried in front of it, leaving these nice records of previous surges. We’re out here now trying to find a mechanism, or trigger for these surges, that might tell us more about why some glaciers surge and others don’t.

We once again fly over the nasty looking lower part of the Black Rapids. The cloud ceiling was still too low to make it all the way up, but it looked better than the day before. So instead of turning back, our pilot set the helicopter down in a nice spot where we could just wait and see what happened. Here is some of that awesome terrain on the way up:

lower glacierRock covered moulin

fresh snow

A fresh dusting of snow on the first big tributary (first picture in this post).

We had a phenomenal view of the landslides from the helicopter. These were enormous rock avalanches that occurred in 2002 after a 7.9 magnitude earthquake on the Denali fault (runs on the south side of the glacier). The debris crossed the entire mile-width of the glacier. This debris insulates the ice underneath, protecting it from melt.

This is a narrow spot between two of the landslides. You can see that the debris layer is actually pretty thin, but has very well insulated the ice underneath.

Looking across one of the landslides. Those boulders are car-to-bus sized.

After a short wait we finally found science!

Martin opens the box at the main Black Rapids GPS station. This is one of the continuous stations that needed to be winterized. It’s also where we had our base camp last April. We also have a drawire on a tripod at this location to measure melt.

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The first station is downloaded, packed with batteries, and vented (we use a special battery that needs air), and it’s time to move on to the one on the Loket tributary.

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A few centimeters of fresh snow on top of ice. This is where we camped for seven days last April (with 1.5 meters of snow beneath us).

The first blue sky in a few days. It only got better from here.

The winterization of the Loket station went smoothly and the weather kept getting better and better.

DSC_4003loading up

On to the base station!


breaking clouds over loket
some glacier tributary

Our base station is on bedrock, so that it is stationary in relation to the GPS on the moving ice. It’s also trickier to find a good place to land the helicopter. When we installed it in the spring we just skied up the hill. Luckily, our awesome pilot made it so we didn’t have to walk far on loose talus slopes.

tucked away

Another successful winterization.

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What a great little pond!

tucked awaypond level

And what a great view across the Loket tributary!

loket

Now we have a hop, skip, and a jump to pick up the batteries and memory cards from our three time-lapse cameras. Much scenery along the way:

bright mountainsmid-day brightness
peaks

Our time-lapse cameras monitor lakes that fill every spring and drain every summer. When they drain, the increased water pressure at the bottom of the glacier lifts the mass of ice a bit allowing it to move faster. We want to see how much each drainage effects the motion of the glacier.

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The first camera is near Aurora Peak, which overlooks the trinity basin. The trinity basin contains the main accumulation area of Black Rapids. It is also beautiful.

Then on to the other two cameras:

r44 and mt. shandDSC_4084
DSC_4123what will the weather do?
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The R44 parked on a hillside and the Black Rapids Glacier.

Now it’s 4:30 in the afternoon and we need to remove four of the summer-only GPS stations. This ends up going a lot faster and easier than we had hoped. All we needed to do was measure the antenna heights and pull out the stations. But, weight was becoming an issue, so in the end we split up. I flew with the pilot to pick up the last of the gear at the main station on Black Rapids while Martin walked down to remove the last two GPS stations on the lower end of the Loket tributary and main branch.

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Flying over some small crevasses on the Loket tributary.

We lift off to grab the last of the gear. Martin is walking toward the lower GPS stations a few kilometers away.

The flight out was filled with stunning afternoon light.

an afternoon in the mountains
looming in the back

This is the Black Rapids River and Valley, draining to the Delta River. The river isn’t visible from the road, and you can only see glimpses glacier ice from it. Having the opportunity to fly over while travelling up to and back from the glacier I really got to witness how spectacular of an area this is.

By the end of the day we had completed all of our primary objectives. With one more day of flying we were able to make a few additional measurements high up on the glacier that will help us determine the velocity of the glacier in the upper region as well. This didn’t require heavy equipment, just a GPS to sit and grab our location at some stake sites, so it was a pretty quick trip in the morning. Pretty day.

Back in the chopper for another morning.

moraines and ponds
River and ponds
confluence
different environments

It was a really windy day and there were lenticular clouds forming over a few of the peaks.

The views of Mt. Shand were pretty spectacular on the way to and from the trinity basin.

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The end of the trip – all of the work is done and we fly out of the trinity basin one last time. It’s hard not to think you’re on the top of the world here. Not our world, but some world.

And that is the end of our first successful field season for this project!

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