Gastineau Channel is a channel between the mainland of the U.S. state
Douglas Island in the
Alexander Archipelago of
southeastern Alaska. It separates Juneau on the mainland side from
Douglas (now part of Juneau), on Douglas Island. The first European to
sight the channel was
Joseph Whidbey early in August 1794, first from
the south and later from the west. It was probably named for John
Gastineau, an English
Civil Engineer and Surveyor.
The channel is navigable by large ships only from the southeast as far
as the Douglas Bridge, approximately 9.7 miles (15.6 km). Between
the bridge and Juneau International Airport, approximately 8.1 miles
(13.0 km), it is navigable only by smaller craft and only at high
The channel is becoming increasingly unnavigable due to shallow water
depths. The two principal causes for this are:
Isostatic rebound following the retreat of glacial ice sheets
Sedimentation and infilling of the
Gastineau Channel by silty sediment
produced by the Mendenhall Glacier and Mendenhall River.
If current trends continue,
Gastineau Channel may eventually become
dry or unnavigable or both.
During isostatic rebound, the Earth’s lithosphere (crust) is slowly
rising due to buoyant forces, following the removal of a large mass on
the surface. This can be likened to an ice cube floating in a glass of
water with a penny sitting on top. The weight of the penny makes the
ice cube float lower, similar to the immense weight of a glacier on
top of the lithosphere. When the penny (glacier) is removed, the ice
cube (lithosphere) “rebounds” and floats slightly higher. In the
geologic case, this scenario happens very slowly. Rates of isostatic
rebound throughout SE
Alaska vary from 0.1 to 1.5 inches/year
depending on glacial history. The approximate rebound rate in the
Juneau area is 0.25 to 0.5 inches/year.
^ Vancouver, George, and John Vancouver (1801; vols. I-VI). A voyage
of discovery to the North Pacific ocean, and round the world. London:
J. Stockdale. Check date values in: date= (help)
^ U.S. Geological Survey Geographic Names Information System:
^ http://www.ggsalaska.org Gastineau Genealogical Society
^ Motyka, R.J. (May 2003). "Little Ice Age Subsidence and Post Little
Ice Age uplift at Juneau, Alaska, Inferred From Dendrochronology and
Geomorphology". Quaternary Research. 59 (3): 300–309.
Wikimedia Commons has media related to Gastineau Channel.
Coordinates: 58°17′42″N 134°24′26″W / 58.29500°N
134.40722°W / 58.29500; -134.40722
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