Tuesday, January 3, 2012

Kiwi Holidays Part 1

            I drove the venerable Nissan up to Fox Glacier on Christmas Eve, after checking the last guest out of Lost Lodge.   I stopped to hike one of the short trails at Ship Creek, an area named for yet another historical disaster in the Haast area.   The ship Schoenberg ran aground north of the creek in the 1860s.   A few months later, part of the ship washed up at the mouth of this cove, got stuck on the sand, and became a fixture of the beach for the next half century as it slowly decayed.   Today there’s a picnic area, a lookout tower, and a couple of short nature trails.   I also stopped at the Lake Paringa salmon farm café.   I was impressed – some of their salmon compare favorably with the size of the ducks they’re sharing the ponds with.   I could almost hear the Jaws theme song playing as the fish were cruising on behind the mallards.   There were little jars with fish food available for purchase; I declined, as the fish look pretty overfed as it is.   All in all, the trip took about three hours, not counting the time I spent waiting for the Nissan’s engine to warm up.

            Once I got to Fox township, I drove out to Lake Matheson in the evening, and walked around the lake.   Lake Matheson is a tourist attraction not so much because of the lake itself, but because if you stand at a certain point on the north shore,  you can (atmospheric conditions depending) get a picture of Aoraki (the tallest mountain in New Zealand) reflected in Lake Matheson.   On Christmas Eve, the weather was fantastic, but the Southern Alps were only showing themselves in bits and pieces, and the wind on the lake was too strong to get a reflection.   The lake was gorgeous anyway.   There were also some nice birds around, including a very obliging kereru (native wood pigeon) who let me take photos of him with Aoraki in the background.   The scenic atmosphere of the lake was somewhat compromised towards the end of the walk, when the car alarm from a campervan in the parking lot was blaring for about twenty minutes.   
A kereru (native wood pigeon) with the Southern Alps in the background.

            Christmas Day, I spent with Fox Glacier.   Although I couldn’t get up on the ice without going on a guided tour (for very good reasons), I took the public trail which ended about 100 yards from the ice.  At least, I thought I was about 100 yards from the ice.   Later, I learned that a substantial portion of both the footpath, and the car park, have been built on top of dead ice – parts of the glacier that became separated from the main mass of ice, and have been subsequently buried in rubble.   Because the rubble insulates the ice, the dead ice can take decades to melt – but it does melt, so every so often, giant sinkholes open up in the car park.   The DOC (Department of Conservation; New Zealand’s version of the NPS)  brings in truckloads of gravel every year to counterbalance the melting and keep the roadbed level.   In fact, between the sinkholes, the floods, the avalanches, and the rockfalls, keeping the road and the footpath open is a continual construction job.  Originally, the glacier access road was built along the east side of the valley.   After a few decades of regularly clearing out rockfall and avalanches off of the road, the DOC rebuilt the road further away from the side of the hill.   As the new road was now closer to the glacier’s outflow stream, it promptly started getting washed out by floods.   At this point, the DOC has basically resigned themselves to the fact that any access road to such a geologically active area is going to be a perpetual construction job.   In two places, the DOC have even built boulder-like dams to try and divert the glacier outflow stream to the opposite side of the valley from the road.   We’ll see how long that lasts…   

            Appropriately, the glacier access area is peppered with warning signs describing the various ways that Fox Glacier could kill you if you venture of off the public path.   Boulders or ice chunks could fall on your head.   Sinkholes could open up under your feet.   Floods could sweep you off your feet, or rise suddenly and cut you off on the wrong side of the river.   Most dramatic of all, you could get caught in a surge wave, which is a glacier’s version of a tsunami wave.   Actually, glaciers have two kinds of tsunami waves.   

This glacier can kill you in the following ways...

            Tidewater glaciers, like the glaciers I visit in Alaska, create waves (usually) by calving ice.   These glaciers terminate in salt water (that’s why they’re called tidewater glaciers), and the salt water works to melt the glacier.   In fact, the part of the glacier that’s below the water melts a lot faster that the part of the glacier that’s above the water.   So, if you look at the face of a tidewater glacier, it looks pretty even – like a big cliff that just happens to be made out of ice instead of rock.   But if you could look at the entire face of the glacier, including the part that’s underwater, you’d see that that nice, stable ice face is actually being undercut.   The ice that’s supporting that big impressive white cliff is melting away.   And when enough ice melts away, part of the glacier shears off, and plummets into the water in front of it.   That’s calving; this is how icebergs are formed.   

            If you’re going to be exploring tidewater glaciers in kayaks, you don’t want to be anywhere near where those chunks of ice are going to fall.   That part’s pretty obvious.   Actually, you want to be even further away from the ice than you think you want to be.   This is where the tsunami waves come in.   

            Tsunami waves are not necessarily caused by earthquakes.  (In fact, the largest wave ever recorded anywhere on Earth was a tsunami wave caused by an enormous landslide, in a place called Lituya Bay, in the Inside Passage.)   Tidewater glaciers are particularly good at creating lots of miniature tsunami waves.   When a big piece of ice is calved off (and by big, I mean something the size of an office building), the water in front of the ice rises so high, and so quickly, that calling it a wave does not do the phenomenon justice.   It is more like the water in front of the glacier suddenly decides that it wants to be thirty or forty feet higher than the water everywhere else.  Which is another great reason why kayaks should never go closer than a mile from the face of a tidewater glacier.   Even if you are too far away for calving ice to hit you directly, the giant tidal waves can make life very interesting for someone in a 14-foot plastic boat.

            One of my colleagues at the Iceberg Lodge’s parent company used to work as a sea kayak guide in Prince William Sound.   There was a particular bluff overlooking the Columbia Glacier that her company used as a lunch spot.   It was about thirty feet above the water, and far enough from the face of the glacier that no one worried about the bluff being swamped by calving.   Until one day a tour arrived at the lunch spot, and sitting on the bluff next to them was an iceberg the size of a compact car.   One can only speculate on what sort of cataclysmic calving event created a wave powerful enough to throw an iceberg that far up a hill.  But it’s a good example of how powerful, and unpredictable, glaciers can be.   

            So that’s one kind of glacier tsunami.   Valley glaciers like Fox Glacier (which are most glaciers that terminate on land) can create another kind of quasi-tsunami, which is known as a surge wave.   First of all, valley glaciers don’t calve.  This is not to say that ice chunks don’t fall off of valley glaciers, because they do (so walking directly up to one still isn’t a great idea), but it happens much less frequently, since there isn’t anything undercutting the ice.   But what valley glaciers have are outflow streams.   (Technically, tidewater glaciers have outflow streams as well, but they’re usually underwater, so they're much less visible.)   The outflow stream is the glacier’s own melt water.   As the glacier’s ice melts, the water forms channels and streams within the glacier itself, all flowing downhill.   You can almost think of the melt water as comprising a miniature watershed inside the ice, with smaller streams joining with others, slowly becoming bigger, and always flowing downhill.    Eventually this water flows out of the glacier, usually through a tunnel at the glacier’s terminus.   

            Glaciers, as I hope I’ve made clear by this point, are not terribly stable things.   Occasionally, a glacier can actually damn up its own outflow stream.   A part of the ice shifts, and blocks that network of channels, and suddenly, the outflow stream begins to slow to a trickle, just like someone turning off a tap.   he only thing in front of the glacier is a big, uneven, gravely streambed.    Meanwhile, the trapped water inside the glacier building up, and exerting more and more pressure on the ice around it.   Eventually, the water's going to find another channel, either following it’s original course, or by breaking through a weak spot in the ice somewhere else in the glacier.   

            What does this mean for someone watching the glacier?   That if you suddenly see an outflow stream dry up, get to higher ground, and turn on your camera.   (In that order, please.)   Because sooner or later, a giant wave is going to come rushing out of the glacier, and the water might not even have the courtesy to follow its original watercourse.  That’s a surge wave.

Surge wave warning sign at Fox Glacier

            The other weird thing about glacier outflow streams is that they actually get higher and higher over time.   If you think of water working on a landscape, most people think of erosion as the main way that water works on a landscape.   If a river runs in the same place for long enough, it wears down the rock around it, and thousands of years later, you get the Grand Canyon.   Glacier streams are a little different.   The outflow streams are constantly bringing down rocks and debris from higher on the glacier, and all of this rock settles out of the water and ends up all over the outwash plain.   Then a flood comes along, fills the outwash plain, and levels off the debris.   Once the flood subsides, the outwash plain looks a lot flatter – but it’s actually an inch or two higher, thanks to all the rocks that the glacier brought down.   According to the guides at Fox Glacier, you can chart the progress of this sediment buildup by watching boulders in the outflow stream slowly get buried as the level of the riverbed creeps up every year.

            Later in the day I got another look at how Fox Glacier has been changing.   After I got back from the public footpath to the glacier’s face, I took another hike up to the chalet viewpoint.   The chalet currently exists as little more that a chimney and a few piles of rocks, but in the 1940s it was the hub of tourism on Fox Glacier.   Back then, getting to the glacier meant walking in from Fox township.   Of course, the glacier was several kilometers closer than it is currently, but the toe of the glacier was squeezed between two steep cliffs, which meant that there was no good way to get onto the ice from there.   The guides’ solution was to hike up an adjacent valley, climb over a low saddle, and drop down onto the glacier from above.   The chalet served as their lunch spot and warming hut.   Today the glacier is nowhere near the old chalet, but the trail still provides a great view of the glacier itself, which is now several kilometers further up the valley.   

Fox Glacier from the chalet viewpoint

            Later on Christmas Day, I went back to the hostel, as the staff were putting on a huge Christmas barbeque for everyone who was staying there.   Out of the twenty or so people at the hostel, three of us were from Alaska.   For us people from the northern hemisphere, I think there’s something about Christmas that calls out for cold weather.   In New Zealand in December, if you want to be cold, your options are either visiting a glacier, or a glowworm cave…

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