Blue Glaciers - Patient Earthmovers
Glaciers, slow rivers of ice, have scoured and shaped
Cook Inlet and Kachemak Bay. Unlike their dynamic
sidekicks, the violent and unpredictable earthquakes
and volcanoes, glaciers are patient earthmovers. These
blue giants begin with the fall of snowflakes. Winter
upon winter, ice age cold prevented melting. Under
pressure, snowflakes compacted to become millions
of interlocking ice crystals. Over time their own
weight causes glaciers to flow downhill, bulldozing
as they go. As glaciers retreat, they shrink in size
because more ice is melting, but the ice continues
to flow downhill.
Since the first ice mass crept southward several
million years ago, the waltzing advance and retreat
of glaciers have sculpted Kachemak Bay. Their movement
contoured mountains, set the course of rivers, left
bench lands, deposited the Homer Spit, and gouged
U-shaped valleys, such as Tutka Bay and Sadie Cove.
© Bill Scott
Landlocked Grewingk Glacier still shimmers above Kachemak
Bay. Today, it has retreated 3½ miles inland, is
about 13 miles long, and covers 30 square miles. It was
first mapped and measured by William Healy Dall in 1880.
Collapse in Time - Grewingk
Before the Landslide
Enoch (Ed) Nordby Collection
Pratt Museum Photo Archives
In October 1967, a huge landslide collapsed into
the lake below Grewingk Glacier. It carried enough
mountainside to fill eleven million dump trucks -
a wedge of earth and rock 2,000 feet tall, half a
mile wide, and more than 600 feet deep. A forceful
wave roared across the glacial flats toward Humpy
Creek - knocking down trees and tumbling icebergs.
The whole flood plain was full of icebergs. Some were
Volkswagen sized. A lot of them had been rolled so that
they were round.
The glacier itself was the culprit. During recent advances,
it ground away rock and undercut the mountainside. According
to the Homer News, when the ice receded, nothing remained
to hold the mountain. It was like pulling a bookend from
a crowded shelf. Experts say it could happen again - this
week or in a thousand years.
-Al Davis, Homer
Thousands of trees and bushes went into
the bay. It messed up the whole Inlet. Fishermen caught
them in their nets. Dead wood, alders, spruce - everything
went into the bay.
After the Landslide
Austin Post, US Geological Survey
| Formation of
Drawing by Richard Reger