Thursday, January 22, 2015

Turnagain Arm Winter Bergs

Looking north towards Anchorage over Turnagain Arm

Looking south towards Turnagain Pass

It is fascinating seeing Turnagain Arm just south of Anchorage each time we make the drive. The difference between low tide and high tide is fascinating, whales make fairly regular appearances, and every so often a bore tide can be fun to watch. Because the tide differential from the lowest low tide to the highest high tide is somewhere around 38 feet, a low tide can appear to drain Turnagain Arm of the water leaving mostly mud flats. A high tide fills it up right to the rocks that hold up the railroad tracks. In the winter that means that the water will freeze and when a tide comes in the ice is pushed up and icebergs build up in a messy pile like you see in the pictures.

One interesting fact I learned about Turnagain Arm from an interpretive sign by Bird Creek is that there is 1000 feet of mud below Turnagain Arm from many hundreds of years of sediments flowing in from those strong tides. Since I learned that I like to try to picture a 1000 foot dropoff below the Seward Highway. Yikes! That's a lot of mud! The process of silt coming in continues each day.

Another day on Turnagain, with more mud on a lower tide

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