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up close to hubbard glacier 接近哈勃冰川

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My visit to a river of ice.
My kayak skims the icy water of a fjord between two steep-sided walls of rock. Several miles away, I can see Hubbard Glacier.

Here in Alaska's Russell Fjord, the glacier pokes its frozen toe-the lowest part of its front edge-into the water. From a distance, the cold blue glacier looks as tall as a school auditorium and as wide as a football field. As I paddle closer, it looms larger and larger. Its face rises three hundred feet above the water, and it stretches out about six miles across.

The glacier is like a frozen river. I cannot see it moving, but I know that the whole mass slowly flows toward the water-toward me-at inches per hour.

Its ice begins as snow that falls on the St. Elias Mountains of Canada. Some places in those mountains are so cold that the snow has been piling up for thousands of years.

When ice and snow build up to a height of about two hundred feet, the lower ice is changed by the pressure of the weight above it. This ice is not brittle. Instead, it is able to move and change shape. It can flow downhill very slowly, like a cube of warm butter oozing down a tilted plate-only slower.

Hubbard is the largest of the glaciers in North America that flow all the way from their mountain birthplaces down to the sea. The ice that makes up the face of Hubbard Glacier has flowed more than ninety miles from the glacier's uppermost ice field.

The glacier has been winding through the St. Elias Mountain Range for more than ten thousand years. From my kayak, it looks as rugged as a mountain of rock.

Making Icebergs
A resounding crack! echoes in the fjord like a clap of thunder. A chunk of ice breaks off, or calves, from the glacier. It topples into the sea, making a splash a hundred feet high. The impact of the ice brings brine shrimp up to the surface from deeper waters. Dozens of sea gulls swoop down to feed on the little creatures.

Map of Hubbard GlacierThe ice chunk, now an iceberg bobbing in the water, is home to glacier worms. Black in color, these worms live in air pockets inside the glacier. The one-inch-long animals feed on microscopic algae. In turn, birds called snow buntings prey on the worms.

Some of Hubbard's icebergs are gray-brown, loaded with gravel and debris that the moving ice has scoured off the sides of mountains.

Because seven-eighths of an iceberg's mass is underwater, it would be dangerous to paddle my kayak too close to any of the several icebergs in the fjord. The icebergs are melting, so they often shift and roll over as pieces break off. When a large one rolls over, it can send out swamping waves.

The beach across from the glacier looks like a used-car lot of ice, with chunks the size of sports cars and two-ton trucks. The ice glistens in the sun; the glare is nearly blinding. The sound of dripping water pings in the dirt.

Cracking Up
Safely on shore, I listen to Hubbard rumble and groan as it breaks apart along deep cracks (called crevasses) in the ice. A loud roar signals that another chunk of ice is about to break off. This piece is a spire as tall as a thirty-story sky-scraper. It hits the water with a terrific splash, then splits into dozens of iridescent icebergs.

The weight of that much mass hitting the water sends out waves that are high enough to surf on. Minutes later, they crash on the water-worn rocks at my feet.

The calving of icebergs is important in the movement of a glacier. If a glacier loses ice from calving faster than it gets new ice from snow, it will become smaller, or retreat. As long as a glacier collects more snow and ice than it loses from melting or calving, it can move forward, or advance.

Hubbard Glacier has a long history of advance and retreat. Around a.d. 1000 the ice filled Russell Fjord and Yakutat Bay. The glacier then retreated greatly and has been advancing for about one hundred years.

The Sound of Rain
Hours past sunset I hear the gentle pitter-patter of rain on my tent. Rain is not unusual in southeast Alaska, even in the summer months. Peering into the night, I'm surprised to see a clear, star-filled sky. The moon shines on thousands of icebergs clogging the fjord.
As the glacier flows off land and into water, huge chunks crack off, forming icebergs.

As the glacier flows off land and into water, huge chunks crack off, forming icebergs.

What I mistook for rain is the sound of air bubbles escaping from ice. The sound is similar to that of an ice cube cracking in warm water. The cause is also similar except that it's magnified by the size and number of icebergs.

I flip through the pages of my tide table. The seawater that fills Yakutat Bay and Russell Fjord is scheduled to begin working its way toward high tide in a few hours. I settle in for the night and wonder what will happen. Will the icebergs drift out to sea when the tide shifts? Or will they be stranded on the beach like the others?

A misty morning reveals that all of the icebergs have disappeared from the fjord. The tide pulled them into Yakutat Bay, where sooner or later they will melt. But Hubbard Glacier will continue to calve, and soon another generation of icebergs will bob in the seawater



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