Many areas on the coast of southern and western Alaska are fringed by mudflats that appear at low tide. They are formed of a finely ground silt that in some areas is several hundred yards deep. This silt has originated from the action of Alaska’s numerous glaciers, which have been grinding away at the surrounding mountains for thousands of years. As these glaciers melt, the silt is carried to the coast in meltwater and deposited as sediment when it reaches the sea. Because tidal ranges around Alaska are generally high, the total area of mudflats exposed at low tide is huge. These mudflats are an important stopover for migrating shorebirds. Various species of burrowing worms and bivalve mollusks are an important source of food for these waders and for the waterfowl that feed on the mudflats through the winter. Harbor seals also use the mudflats as rest areas. The mudflats are dangerous for human visitors, because in some areas they behave like quicksand. Even mud that at first seems firm enough to support a person may in reality be treacherous. A number of people have become stuck and some have even drowned.
Digging for clams
Brown bears are occasional visitors to some Alaskan mudflats, where they dig for Pacific razor clams buried in the mud. They probably find the clams by looking for the small holes they leave on the surface as they burrow down. Extracting them is tricky, since when disturbed, they burrow down further.