Hey kids! Geology Puzzles at the end of this journal!
Glacier Reconnaissance, Day 2Today Ross and Julie took us out to do more of what they call what they call "reconnaissance". By this they mean looking over the landscape to see what's out there, how things have changed since they were here last, and getting the students to think about the big questions (and little questions too, I suppose!) that would lead to an interesting research project.
Yesterday's reconnaissance was out on the fjord, but today's was on land. We hiked up next to and onto the Austre Brøggerbreen glacier. It was an incredible feeling to walk up onto a glacier and see and touch the various features that I've heard about and only seen in books and videos.
The hike was very pleasant – the weather was cooler today than it has been and it was quite overcast. Once we got onto the glacier, the temperature dropped considerably – it must have dropped easily 10 degrees F (not really a surprise when you figure we were standing on a huge pile of ice!).
We're all a bit cold out here on the glacier!
The REU group on the glacier
Me on the glacier surface.
Liz sports many shades of green today!
It took us about an hour to get up to the edge of the glacier, and then we walked along its side (the right lateral moraine – more on this below) where there was a fast moving stream. After a while we found a safe spot to cross the stream and get on top of the glacier. We hiked up on the glacier for a while and Ross would periodically stop and explain the various features we were observing. What a special experience to be right on top of this enormous mass of ice; to realize that the ice is moving – very slowly, but moving – who knows, maybe we moved a millimeter or two today along with the glacier's mass! That would make the return trip back to Ny Ålesund a little shorter than the way there!
Up on the glacier, Ross explains some of the features we are observing
Along the glacier's surface
It was also pretty cool to walk along the rocks with a group of geology students. I am once again impressed by how knowledgeable these students are! I learned a few important geology facts from them today, and collected a few samples to bring back home (I hope it doesn't weigh down my luggage too much!).
Breaking a rock with Daren's rock hammer so I can take a sample back to the classroom!
So what is a glacier anyway, and what do they leave behind?
So it's time to dive into some science! This whole research project is about glaciers, so I figured I'd take the time to go over some basics about what glaciers are, and what you can tell about a glacier from the stuff it leaves behind.
So what is a glacier, anyway? A glacier is a large mass of ice that stays frozen the whole year.
The ice in a glacier is constantly flowing. It flows for a very simple reason – gravity! Gravity will pull the ice that is at a higher elevation down to lower elevations. (Of course, it flows very slowly, way too slowly to see, but some glaciers can move as fast as several feet a year.)
One of the things that geologists can study is called the Mass Balance of the glacier. The mass balance compares how much new snow and ice is added to the glacier to the amount it is losing mass through melting (or icebergs). If the mass balance is zero, that means that the glacier loses the same amount of mass as it gains. In that case, the glacier will not be receding. However, most of the glaciers in this area are receding, which means that they are melting much faster than new snow and ice is added. This is due to global warming.
What's important to remember is that all of the debris that is in and on the glacier moves with the glacier, until the ice that it is on melts away.
At the edge of a glacier, the ice either falls off into the sea (in a tidewater glacier) or, if it is on land, the glacier will end in meltwater. Either way, whatever the glacier was carrying is deposited out. At the edge of a land-based glacier like the one we were on today, the pile of debris that is left behind is called a moraine.
A moraine formed by debris at the base of the glacier that is thrust upward to the surface
A view up the side of the valley where you can see the mountain above. Notice the beautiful folding in the rocks above. I like this picture a lot because you can see so many geologic features in one area, including lateral moraines at the edge of the glacier.
Depending on where and how the moraine forms there are different names. For example, a lateral moraine forms on the side of the glacier. A medial moraine forms where two glaciers meet - essentially their lateral moraines combine together.
Me on the glacier. Behind me you can see a medial moraine.
A lot of the glacial debris is carried by streams under the glacier (called subglacial streams). Eventually these streams may emerge on the edge of the glacier. Around these streams it can be really muddy. Good thing we had our Muck Boots!!
Ross deciding where to cross the stream
The group shows off our Muck Boots!
Daren walks gingerly across the stream. Don't spill your tea!
crossing back over the stream
Streams can also form on the surface of a glacier, called meltwater streams. These tend to be pretty clear water, as they aren't carrying very much sediment. Near where we stepped onto the glacier we observed a meltwater stream meeting a sub-glacial stream. Can you see which is which based on the color?
A surface meltwater stream
Two streams meet - one came from under the glacier, and the other came from on top of the glacier. Can you guess which one?
Along the way we observed lots of other glacial and other geologic features. Two things that I was excited to see were glacial features that are common in the Boston area. First, we saw glacial erratics, which are large boulders carried by the glacier. We have lots of these in the Boston area, so it's neat to see them while still on the glacier.
The edge of the glacier, where you can see several large boulders that were carried down by the moving ice
Ross describing how the ice beneath this rock would remain frozen as the ice around it would melt
Also we saw a kettle lake, which forms when a large chunk of ice is left behind when a glacier retreats. Once it melts, it leaves a depression behind.
Rachel walks in front of a kettle lake (This reminds me of my local pond, Jamaica Pond, which also formed as a kettle pond)
We also saw numerous rocks with glacial scarring, which are grooves that a glacier leaves on underlying rocks as the ice flows over it.
Glacial scarring
We observed rocks that had undergone frost shattering, which is where water seeps into cracks into rocks – when the water freezes the rock is shattered. One of these was a huge boulder that looked like it had exploded!
This rock has broken apart completely because of frost shattering
Another feature that Julie pointed out to us was permafrost rock sorting. Essentially what happens here is that as the ground freezes, it gets pushed up by the expansion of ice. The cycle of the ground getting pushed up and down by the freeze-thaw cycle causes the rocks on the surface to literally get sorted by size.
These rocks were sorted by the freezing and melting cycle of the permafrost!
A couple of unrelated sights from today. We saw was bear scat! Guess the bears really are around even though we haven't seen any...
Bear Scat
Also, we had to walk by this structure, called a "utilidor" which is a structure for holding pipes and wires above the ground – it's too difficult to dig into and maintain pipes in the permafrost, so in Arctic communities it is common to see these kinds of structures for holding pipes. This was quite an old one, perhaps dating from the coal mining days. Note the amount of insulation around the pipe to keep whatever was flowing in it warm.
An old
What was helpful today for the upcoming research was to see all the different ways that the glaciers can deposit material. Most of our work over the next few weeks will be looking at tidewater glaciers and what their sediments tell us. Obviously we can't see directly what's happening under water, so it was helpful to see these processes on land.
We finished our hike and came back for dinner. Then we had a chance to watch the women's World Cup soccer game! What a tough loss for the US - our consolation was seeing the world's most amazing view from the window as we headed off to bed.
Watching the world cup soccer game!
Puzzles for today:
Puzzle #1:
Here's a good geology puzzle... We saw a pile of very dark mud on the glacier's surface. It had a very definite decomposing smell, which indicates organic material, the kind that would form at the bottom of a lake or pond. Can you guess how stuff from a pond might form on top of a glacier, and in a mound shape??
Mound of organic material on the glacier surface
Puzzle #2:
Here's another little puzzle. Can you guess what this is?
What's this?
Puzzle #3:
Listen to this sound. Can you identify the source of this sound??
Think you know the answers to these? Write a response in the "Ask the Team" section of this website.