Iceberg in Glacier Bay
Icebergs
Huge icebergs may last a week or more. They provide perches for bald eagles, cormorants, and gulls, as well as haul-outs for seals. When passing close by, kayakers can hear splashes and crackles as melting water drips and the ice deteriorates. The ice pops and sizzles as it releases ancient air first trapped between the delicate snowflakes and then frozen in under pressure – a phenomenon called “bergie seltzer.”
Colors betray a berg's nature or origin. White bergs hold many trapped air bubbles. Blue bergs are dense and are likely recently calved. Greenish-blackish bergs may have calved off glacier bottoms. Dark-striped brown bergs carry morainal rubble – rocks that the glacier acquired on its journey down the mountain.
How high a berg floats depends upon its size, the ice's density, and the water's density. Bergs may be weighed down or even submerged by rock and rubble. A modest-looking berg may suddenly loom enormous – and endanger small craft – when it rolls over. Boaters and especially kayakers should keep in mind that what one sees is "just the tip of the iceberg."
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