This one is Margerie Glacier, arguably the most impressive
of all, and one that has not retreated for many years.
It is some 20 miles long, what we see at this end is 250ft
high and a mile wide.
It is constantly calving, it travels at a rate of 6 feet a
day, and we witnessed a few of its smaller ice falls as we sat there for almost
an hour.
This detail shows the rock and ground up rock that the glacier carries
with it and deposits as a glacial moraine in the waters below. Just above the
darker lines you may see that the ice is blue, this is caused by the filtering
out of the other colours due to the pressure of the ice that is completely free
from air.
This cave was made by a collapse that we just missed, you
may see the floating ice in the water, a tiny proportion of that which has just
come down.
Immediately adjacent to Margerie Glacier is the Grand
Pacific Glacier, even larger than her sister, but carrying much more rocks and
other detritus giving it the appearance of a cliff face. But it is all trapped
in ice, and probably contributed more than other glaciers to the carving out of
Glacier Bay over the millennia.
As I noted earlier, the whole of Glacier
bay was itself a glacier as recently as 1780, perhaps this may
will show you how it has retreated over the past few centuries. From time to
time it comes a little further down, but generally it is retreating.
George Vancouver was the first to see this area in 1795, at
that time he was only able to travel 5 miles up the bay.
The Lamplugh Glacier also protrudes into the Bay, and is one
of those that is now longer than it was in the middle of the last century and
still growing, but glaciers all depend on winter snowfall at their source so
things can change over a century. This glacier comes from the Brady Icefield,
some 50 miles inland. This field gives birth to at least eight glaciers,
falling in all directions.
One of these is the John Hopkins glacier at the end of the
inlet of the same name. There are more than ten glaciers which reach Glacier Bay , with many more in the mountains above that
send their melt water down.
As a result we can see changes in the water composition,
here there is salt water alongside glacial silt water, quite a change in
colour. Some of these glaciers, for example the Grand Pacific, deposit muddy
water into the bay, which settles out in the calm waters.
The waters here are very deep, the glacier which formed the
Bay was up to a mile high, and carved out the basin below us along with the
mountains at either side. This stream appears to come all the way from the top
of this mountain, probably from another glacier.
Our captain revolved the ship several times so that we could
all get good views from our balconies, and this cheeky bird landed on the next
door balcony and took a good look at us!
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