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Alaskan Glaciers
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 Most of these huge rivers of ice have been retreating
(growing smaller) since the mid-1700s. As they move,
they carve out deep valleys. A tidewater glacier is one
that lies at the head of the fjord or inlet it created.
A calving glacier is one with chunks of ice falling off
into the sea below. The crack or rumble of a glacier
calving can sound like a thunderclap. The visible part
of a floating berg is usually only about 1/6th of its
total mass. The blue colour of some glaciers or bergs is
because smooth ice reflects long-wave colours (blues).
Glacial melt water often appears milky turquoise in
colour because of fine sediments it carries.
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Tracy Arm and adjacent Endicott Arm are steep-walled
fjords with active tidewater glaciers at their upper
limits; Sawyer Glacier at the end of Tracy and Dawes
Glaciers for Endicott Arm. Large bergs can weigh up to
thousands of tons and cause sizeable waves when they
fall into the sea. The sheer cliffs of these fjords
average 2,500 feet (760 m) and can be home to
wolverines, black and brown bears, deer and mountain
goats.
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- Glacier Bay was first explored by John Muir in 1879,
hence, the largest glacier bears his name. After he
wrote about this extraordinary valley with its dramatic
glaciers, Glacier Bay became a regular stop for early
cruise ships like the Ancon, the Idaho, and the Queen.
Although the ice has receded considerably since Muir
first saw it, cruise ships still make regular visits.
Home to some 16 tidewater glaciers, Glacier Bay National
Park is often called one of the seven natural wonders of
the world.
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- The Hubbard Glacier is the longest tidewater glacier in
North America at a length of 76 miles (122 km). Only 600
years ago, the glacier completely covered Yukutat Bay.
Now its face is six miles wide (10 km). Hubbard Glacier
made headlines in the summer of 1986 when it advanced
hundreds of feet in a few weeks. In the process, it
dammed the entrance to Russell Fjord, trapping seals
inside what was suddenly a huge lake. When the ice dam
finally ruptured, some 3,500,000 cubic feet of water per
second poured into Disenchantment Bay.
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