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Logo bar of the Alaska Public Lands Information Center which are located in Anchorage, Fairbanks, Tok and Ketchikan
A fiery sunset reflects on the cool blue waters of cook inlet. A bank of low clouds makes for a dramatic scene.
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Mudflats or mud flats
 
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Mudflats form when silt and mud are brought in by seas, oceans, and tributaries. The mud and the silt are deposited into bays and lagoons when the tide comes in. The water mixes with the mud and silt, creating the muddy quicksand that occurs in mudflats. Once the tide lowers, the mudflats are exposed along with what inhabits them.



The Mudflats in the Cook Inlet

On July 15, 1988, a tragic accident on the mudflats of Turnagain arm near Portage, Alaska claimed the life of newlywed, Adeana Dickison. She had become mired in the wet silt that is exposed twice every day by the outgoing tide. The ATV driven by her husband had become stuck in the mud and while pushing the vehicle, her leg sunk to her knee. Unable to free her, her husband summoned help, but it arrived too late. The incoming tide rushed in and inundated her. Hypothermia was also a factor as the water was extremely cold.

There is a lesson to be learned here; don’t venture out onto the mudflats of Knik Arm, or Turnagain Arm for any reason. While it is true that some areas are drier and more stable than others, you may find it necessary to cross wet areas which are more dangerous. Also, you may be overtaken by the onrush of the incoming tide which comes in at over 10 miles per hour. At that point all the silt is obviously wet, and when that happens, you sink into the silty mud.
 
Microscopically, the silt particles are laid down in a delicate, loosely oriented pattern by waters that carry them into the inlet. When disturbed by your foot, these particles resettle into a more tightly packed arrangement, making extraction much more difficult. These super-saturated particles, called glacial flour, are ground up by glaciers and carried by streams into the inlet. That’s what gives the waters of many Alaska streams their muddy gray appearance.

Unlike mudflats in other parts of the world, Turnagain and Knik Arms have little year-round life forms. Light cannot penetrate the silty water, so no plants, with the exception of popcorn kelp found on the shoreline, can grow in the arm. The only fish in the arms are migrating salmon and smelt, and the only mammals are those seeking to eat the fish.

Turnagain Arm is a beautiful place and offers a chance to see a unique phenomenon called a bore tide. The Bay of Fundy is the only other place in North America to witness this tidal display. To learn more, click HERE.  





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