Glaciers and Icebergs of Glacier Bay National Park in Southeast Alaska

As you enter Glacier Bay in Southeast Alaska you will cruise along shorelines completely covered by ice just 200 years ago.

Explorer Captain George Vancouver found Icy Strait choked with ice in 1794, and Glacier Bay was barely an indented glacier. That glacier was more than 4000 ft. thick, up to 20 miles or more wide, and extended more than 100 miles to the St.Elias Range of mountains.

By 1879 naturist John Muir found that the ice had retreated 48 miles up the bay. By 1916 the Grand Pacific Glacier headed Tarr inlet 65 miles from Glacier Bay's mouth. Such rapid retreat is known nowhere else on earth! Scientists have documented it, hoping to learn how glacial activity relates to climate changes.

Calving Glacier courtesty of Bill and Marge- Goodriver Bed and Breakfast

Glacier Bay National Park includes 16 tidewater glaciers:12 actively calve icebergs into the bay. The show can be spectacular. As water undermines the ice fronts, great blocks of ice up to 200 feet high break loose and crash into the water.

The Johns Hopkins Glacier calves such volumes of ice that it is seldom possible to approach its ice cliffs closer than about 2 miles.

The glaciers seen here today are remnants of a general ice advance- the Little Ice Age- that began about 4,000 years ago. This advance in no way approached the extent of continental glaciation during Pleistocene time. The Little Ice Age reached its maximum extent here about 1750, when general melting began.

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Photographic delights include enormous ice calvings falling hundreds of feet from Alaska's most active glacier, great wildlife portraits, and spectacular scenery...

Glacial Formation

Glaciers form because the snowfall in the high mountains exceeds snow-melt. The snowflakes first change to granular snow- round ice grains- but the accumulating weight soon presses it into solid ice. Eventually, gravity sets the ice mass flowing downslope, usually far less than 4 to 7 feet per day. The point at which the rate of melt equals the rate of accumulation is the glacier's terminus or snout.

If the glacier's snout reaches tidal waters, we call it a tidewater glacier.Today's advance or retreat of a glacier snout reflects many factors: snowfall rate, topography, and climate trends. Glacial retreat continues today on the bay's east and southwest sides, but on its west side several glaciers are advancing.

Icebergs and Glaciers galore...

WORLDWIDE GLACIAL FACTS:

* Glaciers and polar ice store more water than lakes and rivers, groundwater, and the atmosphere combined.

* Ten percent of our world is under ice today, equaling the percent being farmed.

* If the world's ice caps thawed completely, sea level would rise enough to inundate half the world's cities.

* The Greenland and Antarctic ice caps are 2 miles thick.

* Alaska is four percent ice.

A Birthplace of Icebergs

Calving glacier courtesy of Melinda Webster As glaciers find the water's edge, the result of a long deliberate push towards the Glacier Bay, they "calve" in a thundering splash, releasing Icebergs large and small to the awaiting bay.

As kayakers pass by these floating giants, they have heard the stress and strain of melting: water drips, air bubbles pop, and cracks develop.

Huge icebergs may last a week or more before the finish there transition back to liquid water.

Colors betray a berg's nature of origin. White bergs hold many trapped air bubbles. Blue bergs are dense. Greenish-black bergs calved off of glacier bottoms. Dark- striped brown bergs carry morainal rubble from the joining of tributory glaciers, or other sources.

Birds on Iceberg How high bergs- favored perches for bald eagles, cormorants, and gulls- float depends on size, ice density, and the water's density. Bergs may be weighed down, submerged even, by rock and rubble. A modest- looking berg may suddenly loom enormous, and endanger small craft, when it rolls over.

Keep in mind that what you see is "just the tip of the iceberg."

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Glaciers & Icebergs of Glacier Bay National Park

Tidewater Glaciers

Spectacular Glacier Calving DVD's for sale!

Glacial Formation

A Birthplace of Icebergs

Glacier Bay Park

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