Tegan’s Science Notes #8: Glaciers

capt_dave_ac_125Dave Rearick: As promised, here’s the second half of our Glacier Report, the first part of which with my notes, photos and videos of my trip to Fox Glacier is viewable HERE!

Today’s follow-up post, from our Earthwatch Scientist, Tegan Mortimer summarizes much of what science has learned about glaciers. Tegan knows a lot about glaciers, so I encourage you to read on and learn more about this important subject.

And if you would like to share these learnings with those younger than yourself, be sure to check out our new (and easily printable) Explorer Guide on Glaciers - or engage Tegan or I with questions via email.

So, take it away, Tegan! 

1. The Power of Ice: Discovering the Glacial Landscape

Tegan MortimerTegan Mortimer: Did you know that Charles Darwin was a geologist? Many of the thoughts in his most famous work, The Origin of Species were influenced by early discoveries in geomorphology - a field of science which tries to explain how landscapes change based on the pressures placed upon them. Ice is one of the greatest creators of landscapes. Just as Dave described the Great Lakes being carved out by glaciers in his previous post, in that same way was Cape Cod along with many other features of my native Massachusetts coastline also carved out by glaciers. When you really look closer, it’s possible to discover much of the history of a landscape by the way it looks today.

The photo below is of a place in North Wales called Cwm Idwal (in Welsh a “w” is a vowel and is pronounced like “oo”) in the Glyderau Mountains.

cwm_idwal_560Cwm Idal in the Glyderai Mountains of North Wales

Charles Darwin visited Cwm Idwal in 1831 to study the many fossils of ancient marine life that were found in its rocks. What they showed was that this land was once the bottom of the sea! For Darwin and his fellow geologists who were trying to show that landscapes could be shaped and changed in this way, these findings were so exciting that they somehow missed something even bigger!

It was another 10 years before Darwin returned to Cwm Idwal and this time he noticed the very obvious evidence of glaciation on the landscape. Cwm Idwal is what geologists call a “hanging valley” (alternately called a cirque, or a corrie or a cwm), which is the area from which a mountain glacier originates. Below Cwm Idwal, stretches a wide glacial U-shaped valley, which reaches all the way to current sea level. Cwm Idwal and the surrounding area are a wonderful example of “typical” glacial features.

2. How glaciers change the landscape

Glaciers and ice sheets form landscapes through two methods. The first happens when glaciers erode the landscape by scraping up the soil and bedrock after which they then deposit this material in other places.

NZ_scavenger_hunt_sidebarDepending on the type of rock that a glacier is moving over, different glacial features will be left behind. Soft rocks like sandstone or limestone are easily ground up by the pressure of the ice, while harder rocks like granite are usually eroded through a process called “plucking.” What happens here is that water from the glacier melts into cracks in the rocks which than refreezes. As the ice in the glacier moves, it plucks away pieces of rock which are then trapped in the ice. Water expands when it freezes and is capable of further breaking apart rocks in what is called “freeze-thaw weathering.

(:: For a fun sidetrip, explore Fox Glacier via Google Earth by clicking on this link or the image above!)

The second method of erosion results in a roche moutonnée or a whaleback, which is an area of exposed bedrock, which has a smooth gently-sloped side and a steep vertical side. The photo below shows a few roche moutonnées which are only a few feet tall, though it is possible to see very large ones as well. Based on the direction of the sloping and angle of the sides you can tell which direction the glacier was moving. Remember that fact, as it will come up again later. The sloping side is the direction the glacier was coming from and the ice grinds down that side of the rock. The steeper sided angle is the direction the glacier was going and here is where that process called plucking happens. The tops of roche moutonnées often have scratches called striations which are horizontal scape marks from the rocks and debris in the ice.

Roche moutonnées

Crag and TailAnother erosional feature is called a crag and tail which is a tall hill usually with exposed rock and a gently sloping tail of softer rock behind it. In this case, the steep side of the hill is the direction that the glacier came from. The most famous crag and tail is Edinburgh Castle (pictured to the left)  in Edinburgh, Scotland. The crag in a crag and tail is an area of very hard rock, usually a volcanic plug which forms when magma cools inside the vent of a volcano creating a column of very hard rock. When the glacier hits this rock, it can’t erode it, so it is forced to flow around the plug like water flowing around rocks in a stream. The plug protects the softer rock behind it leading to the formation of the tail.

All that eroded material has to go somewhere, so it is that glaciers leave behind particular landforms made up of all that “stuff.” Sediment left behind by glaciers is usually called till, which is made up of sand and gravel and rocks of every size. Erratics are large rocks like the photo below which are left behind by a retreating glacier. Geologists study the mineral structure of erratics to learn where they come from and learn more about the behavior of glaciers and ice sheets.

An Erratic

Glaciers push up ridges of material which are called moraines. These ridges can be formed at the base of the glacier which are called terminal moraines or at the edges of the glacier which are called lateral moraines. Cape Cod and Long Island on the US east coast are areas which have a series of terminal moraines formed thousands of years ago by the Laurentide ice sheet. As a glacier retreats, it can leave behind a series of terminal moraines which reflect the extent of the ice at different periods. Sometimes meltwater from a glacier will be kept from exiting a valley by a terminal moraine and will form a lake.

3. Glaciers Today

So what exactly is a glacier? Dave explained it pretty well; a glacier is essentially a river of ice. A river of ice? Since you can’t see it moving, how can that be? The fact is that glaciers are always on the move. The immense weight of the ice in a glacier causes it to deform internally, which results in unstoppable movement. Gravity and meltwater underneath the glacier can also help it to move downslope. The areas at the edges of the glacier are under less pressure so this is where great cracks in the ice called crevasses form. When pieces of a glacier fall off the base of the glacier it is call calving – which is happening lately at a much increased rate. Here is an incredible high-def clip from a recent movie called “Chasing Ice” that records the longest and biggest calving ever recorded.

We know Fox Glacier is retreating, so how then is it moving downhill? The growth of a glacier is based on something called mass balance. Snow falls on the top of the glacier and freezes while ice from the bottom of the glacier melts or breaks off, a process that is called ablation. As long as the accumulation at the top outweighs the ablation at the bottom, the glacier will grow. However, if the ablation outweighs the accumulation, then the glacier will retreat. This is the case of the Fox Glacier, and unfortunately the case for many glaciers around the world.

4. Does it really matter if the glaciers disappear?

It would most certainly be a tragedy if alpine glaciers were to disappear due to the effects of human climate change. They are majestic places to behold and also provide revenue from tourism to areas in these regions. However, and more importantly, glaciers also provide huge stores of fresh water, which are released throughout the year. For example, about 1.3 billion people depend on Himalayan glaciers for drinking water and other water needs. If these resources were to disappear, it would have devastating effects on human populations.

5. Glaciers of the Past

At times throughout Earth’s history, huge swathes of the planet have been covered by ice. We know that some of these ice sheets covered thousands of miles and could be several miles thick. Such ice ages can last for millions of years and go through a series of glacial and interglacial periods where ice cover increases and decreases. The last ice age started 2.6 million years ago and is still ongoing today. We are currently in an interglacial period called the Holocene, which started 12,000 years ago. When people talk about the “Ice Age” they are usually talking about the previous glacial period, which occurred from 110,000 to 12,000 years ago. The ice was at its greatest expanse just 22,000 years ago when most of the northern half of North America and northern Europe and Asia were covered in ice. In the Southern Hemisphere, the Andes in South America and Southern Alps in New Zealand had large ice caps as well.

glaciation_560The glaciated landscapes of North America, Europe, South America, and New Zealand were formed during this Ice Age.

6. What happens when massive ice sheets disappear?

The most important thing to remember is that ice sheets (and glaciers) hold a huge amount of water. The sea level was about 120 meters lower during the last glacial period than it is today. We still have two major ice sheets on earth, the Antarctic Ice Sheet and the Greenland Ice Sheet. If these were to melt – which they give every indication of doing, and quite rapidly, we would see increases to sea level, which would threaten many coastal cities and sea-dependent communities across the globe.

See all Dave’s photos and videos from Fox Glacier right HERE!

– Tegan

:: Tegan Mortimer is a scientist with Earthwatch Institute. For more exciting science insights, check out our BDX Explorer Guides or stop by our Citizen Science Resources page, where you can also find all of Tegan’s previous “Science Notes.”

We welcome your input or participation on our BDX Learning Discovery efforts. You can always reach us here or via email.

Glaciers – Dave’s Full Story

Fox Glacier – The Power of Ice

As some of you may recall, back in February on my layover in New Zealand, I visited Fox Glacier on the South Island. After so many years of being surrounded by water in its liquid form, the experience of being enveloped by frozen waves of water cracked open my curiosity in completely unexpected ways.

Seeing the power that glaciers had to literally move mountains and at the same time to witness firsthand the incredible speed with which they are disappearing right before our eyes was something I knew I had to further explore … both for myself, and for those of you who have engaged with us in the learning and discovery side of our adventure.

Dave at Fox GlacierDave at Fox Glacier

Though I know that what follows here (broken into two installments) is a larger than usual amount of information for the narrow confines of a blog post or an email, here’s what we’d like to share with you today!

  • In addition to our six earlier Explorer Guides, with our scientist colleague Tegan Mortimer‘s help, we’ve gathered our essential learnings on glaciers and complied them into a newly designed and easily printable Explorer Guide on Glaciers! We encourage you to check it out – and to once again … share it with the younger people in your world.

Explorer Guide - Glaciers
Here’s our new Explorer Guide on “Glaciers – The Power of Ice”

  • Given some time to reflect, I include below some new reflections of my own on the whole glacier experience. (My earlier Fox Glacier post is HERE!)
  • In addition to the glacier photos - here in slideshow format, we’ve also added five new videos to our BDX YouTube Channel from that day – each one fairly short, but each also showing some unique aspect of the glacier.

:: As this is a long post, and as Tegan has such a passion for the subject of glaciers and has so many great science findings to share, we’re following this with – Tegan’s Science Notes #8: Glaciers … which contains some very exciting and excellent insights on glaciers. She also includes a fun Google Earth Scavenger Hunt you can explore on your own!

We know it’s a lot of material … but there’s nothing small about glaciers … and as we are quickly learning, the fate of our planet is as much tied to the vitality of our glaciers as it is to that of our oceans.

So, ALL that said … let’s get rolling … !

capt_dave_ac_215Dave Rearick: Growing up on the shores of Lake Michigan, the second largest of the five Great Lakes, gave us every chance to learn about glaciers. Glaciers scoured out all five of the Great Lakes about 10,000 years ago. As they melted and retreated, they left distinctive land formations: great carved moraines, bogs, kettle lakes and wetlands, not to mention, the amazing fresh water lakes themselves.

Lake Michigan is over 300 miles long (483 km), 90 miles wide (145 km) and over 900 feet deep (275 meters) at the deepest point. What I learned in school about glaciers at the time just sounded like more ancient history and did little to prepare me for my recent visit to the Fox Glacier on the South Island of New Zealand.

For the past several years, we’ve all heard story after story about how human activity and global warming have affected glaciers around the world. Experiencing firsthand their amazing scale and force, as well as the incredible speed with which their dissolution is happening, brought those many stories to a very different level of reality for me. It also reinforced for me the amazing power and need for hands-on learning in and around nature, much like what we are trying to do through our Bodacious Dream Expedition updates that track my circumnavigation and by our now seven topic-specific Explorer Guides.

#1 - Click arrows to advance! Scroll over to read descriptions.

As you hike up the glacier, you can easily see the various markings that the receding glacier had left. Just five years earlier, in 2008, the glacier had scoured the hillsides to a height that was now clearly marked by a vegetation line, below which was barren rock, over two hundred feet above us!

The access paths to the glacier must be regularly reworked. Just a year earlier, the path was about 50 feet higher up the side of the canyon wall. We learned that the glacier was melting at the rate of 6 inches (15 cm) a day! That’s 3.5 feet a week, 15 feet a month, 180 feet a year! Glaciers don’t do anything quickly, but they sure do it steadily. They gather snowfall up in the mountains, compress it so that it must move with gravity, ever so slowly changing and sculpting the earth on its way. Natural history unfolds, and the story of the Earth is told by these slow moving rivers of ice. What looks to the casual eye to be a static natural wonder, is in fact a dynamic display of the forces of nature undergoing constant and rapid change.

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Each step of the hike exposed us to more wonder and amazement. There is so much beauty in the color and shape of the ice, and in tracking the constant changes brought on by the ever-flowing ice and water.

Be sure to check out our Explorer Guide on Glaciers for more amazing learnings!

I hope you enjoy the videos taken while at the glacier. They may not be of a professional travel brochure quality, but I think they offer a true and authentic entry into the story and into what you yourself might experience on the glacier if you were to go there. The rains and fogs of the day certainly added their effects as well, but to me, they all combine to show the stark beauty and harsh contrasts of this hard yet fluid environment – much like my videos of the stormy tempests at sea revealed the powerful nature of the ocean.

I hope that if one day you have the chance, you will choose to experience a glacier firsthand. If you do, I would recommend you hike rather than take the helicopter ride. I am sure the helicopter ride is beautiful, but you will land on a very static snowfield up on the higher slopes of the glacier, and you might miss the story of these fascinating indicators of our environment, that are unfolding farther down towards the terminal face.

Of all the sights I witnessed that day, the one that stood out for me was the one about this enormous boulder, about the size of a small truck, tilted up on its edge as if it might at any moment fall over.

FG_boulder_300The Fox Glacier Guides have been keeping an eye on this boulder for five years, ever since it first appeared, after having been carried down by the glacier. In those five years, they have seen the boulder reposition itself in many different angles and positions, but no one has ever actually seen it move! That is the power of the earth and nature – the capability, one drop at a time (or one wave at a time) to move a boulder or wash away a shoreline. If you’ve ever wondered just how your single life could have an impact on the larger world, I think somewhere in such a truth might be your answer.

 #3 - Click arrows to advance! Scroll over to read descriptions.

As I mentioned at the top, tomorrow we’ll follow up this post by publishing Tegan’s Science Notes #8: Glaciers … so we hope you’ll look for and check that out!

Again, thanks so much for following along … and if you should have any questions – or suggestions, don’t hesitate to drop us a line at oceanexplorer@bodaciousdreamexpeditions.com

- Dave
21.85887S, 97.30453W

P.S. I just learned about this amazing set of photos from a photographer named James Balog who has spent years taking photos of vanishing glaciers … truly outstanding and sobering images  … http://billmoyers.com/content/vanishing-glaciers-now-and-then/

Fox Glacier Excursion

The South Island of New Zealand generously provided a number of amazing experiences over the week I toured it recently, but the one experience that stood out for me was a visit to the Fox Glacier, located near the coast in the Westland Tai Poutini Park near the small town of Fox Glacier.

Fox GlacierFox Glacier in New Zealand’s Westland National Park

We’ve all heard news reports that drum into us how the glaciers of the world are melting away, and what significance this might have. Getting the chance to see a glacier firsthand and up close made clear the pressing reality behind those reports. As you may know, I am a student of the world at large and especially of the natural wonders of the ocean, but nothing in my many wanderings prepared me for the transcendent beauty and force of a glacier.

DSCN2321A sample of the visions to be found. See slideshows below for much more.

The Fox Glacier moves down from a bowl area that sits higher up in the mountains where the snows collect and remain year-round. These snows pile up and compress under the weight of many years of previous snows, which turn into this massive river of ice that works its way down through the rocky passes and towards the ocean. In the case of the Fox Glacier, its terminal face, curiously enough, ends in a rainforest on the coast of the South Island.

crampons_300Upon arriving at Fox Glacier Guiding, we were fitted with boots, crampons (spikey boot attachments for walking on ice), special waterproof coats and pants, gloves and hats, after which we got special instructions and training from our guides. Once ready, the 20 of us boarded a bus for the three-mile drive to the parking area at the base of the glacier.
As we began our hike to the glacier, our guide Jess explained that the barren rock on the walls of the river canyon gave clear indications of where the glacier was as recently as 2008. Just five years ago, the ice was significantly higher up the walls of the canyon – (over 125 feet) and it reached a good deal further down towards the ocean. Maybe “significant” isn’t a powerful enough word … perhaps the photos can tell a better tale.

#1 - Click arrows to advance! Scroll over to read descriptions.

We hiked up to the terminal face and then up into the glacier itself, where for the rest of the afternoon, Jess took us past enormous holes where melting water runoff was eating away at the glacier. We hiked past caves and crevasses, up into ice canyons and through ice tunnels, all of such pristine beauty and stillness that it was hard to keep in mind the stark reality that this glacier was melting away at an alarming rate.

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As we came down from our last ascent, we looked across about 30% of the glacier that was too dangerous to traverse. Jess explained to us that this area was being eaten away by the river, and the unseen melt below was causing a collapse inward. From where we stood, we could see the unstable cave from which icy water rushed out. Jess further explained that by the end of this season, the entire area might well wash away and that within a couple of years, the entire terminal face of the glacier might be too unstable to access by foot.

 #3 - Click arrows to advance! Scroll over to read descriptions.

These monumental forces of nature, not unlike the ocean, do indeed work away at a glacial pace – one drop of water at a time, one blade of grass at a time, one gust of wind at a time, one wave at a time, and as they do, they slowly alter the face of the planet.

Here are some amazing facts I learned about the Fox Glacier:

· There are over 3000 glaciers in New Zealand!
· The Fox Glacier is one of the few in the world that ends in a rainforest before emptying into the ocean.
· The glacier is over 1000 feet thick (300 m) at its deepest point
· The glacier flows at the rate of 600 feet (183 m) per year
· The thickness of the ice near the terminal face is up to 100 feet (30 m) thick
· The river is about 80% melt off from the glacier.
· Measurement of the amount of change in ice thickness is done by placing long pieces of pipe called ablation poles, vertically into the glacier. They start level with the ice surface and gradually become exposed as the glacier melts. At the time we were there, one meter of pipe was showing, indicating about two weeks’ worth of change (melt).
· Estimates are that in about two years’ time, the glacier’s terminal face will no longer be accessible by foot.
· Half the glacier is contained in the upper “bowl” area where the snow collects and compresses into ice.
· The other half is called the “tongue,” which is the mass that flows down to the river area.
· The fissures and crevasses happen perpendicular to the compression stress of the glacier; closing and opening as the great masses of ice move and shift daily.

I feel humble and fortunate to have had the chance to experience these things firsthand and to share them with you. Rather than continue at this point with more words, how about we leave you review the photos of this amazing place in the three slideshows …  or view them as an album on our BDX Facebook Page - and check out this video below that shows that slow moving boulder … more videos to come soon here … and on our BDX YouTube Channel.

And also very soon too, we will have ready for you a new Explorer Guide on the Fox Glacier, so that you can read and learn more about this world landmark.

Big Thanks,

- Dave

P.S. Here are a few Wikipedia links … to Fox Glacier, located near the coast in the Westland Tai Poutini Park near the small town of Fox Glacier.