We’re back on the glacier. It’s time for summer skiing. We have been doing this for about ten years
now. In the beginning of the school's summer vacation we go skiing on a glacier.
It has become part of my duty as a ski dad, because my boys are addicted
to snow (and I've posted about this before).
Actually, this year it’s only little boy and me. Older boy
is running around on his own, with his buddies. This summer they have picked a
different glacier. They’re driving down to the Alps, to spend 3-4 weeks on a
glacier in Austria. That’s OK with me,
as long as he works to earn up the money himself.
Little boy and I made it simple. We went to the closest
glacier, a four-hour drive from home, and we stay in the same camping down in
the valley. We plan to ski four or five days, depending on the weather. So far
it’s been shifty; partly sunny yesterday, snowy and foggy today, good forecasts
for tomorrow.
Being on a glacier is quite amazing. We’re skiing on snow
and ice that fell hundreds of years ago. Actually the surface is not that old.
The snow we skied today fell last night.
Some years ago I bought a text book on glaciology, to learn
about the science of glaciers.
The core of the glacier is old. When the snow is buried it
gradually turns into ice that moves by plastic flow. The weight of the ice
makes it flow from the top to the bottom, slowly, but steadily, a few meters
per year. When pieces on the lower edge break off, the old bluish ice becomes
visible.
Big glaciers are very useful for climate research, because
glaciers keep a record of past climate.
The ice in the core contains small sealed air bubbles. This allows scientists to measure for
instance the CO2 levels of past times.
There are two main types of glaciers; polar (cold) glaciers
and temperate (warm) glaciers. Polar glaciers
are found in the Antarctica and the Arctic (e.g. Greenland). They’re often frozen
to the rock surface below. The glaciers on the American and Eurasian continents
are mostly temperate. They’re near the
melting point, with free flowing water at the base.
In the upper part of the glacier, the accumulation of snow
and ice is larger than the melting (and sublimation). In the lower part it’s
opposite. The line of zero net accumulation (over a year) is called the firn
line.
When glaciers flow over the terrain beneath, they’re
squeezed and stretched such that crevasses are formed. Crevasses can be deep
and dangerous. Therefore many glaciers are not suited for skiing.
The glacier where we’re skiing has a nice and smooth
surface. There are just a few small crevasses near the top. That’s the way it was last summer. This year
I haven’t checked.
That’s one of the things that make glaciers so interesting.
They’re changing all the time. Every summer there’s something different, if you
have the curiosity and patience to look closely.
(Some pictures taken with
my cell phone at the glacier. (1) Skiing at the glacier. (2) A cool rock by the edge of the glacier. Great forces are needed to form a mountain range. This rock have
experienced both metamorphosis and faulting . (3) At the lower part of the
glacier the old bluish ice core is visible.)
