Coal Point, Homer Spit

Coal Point, Homer Spit

by | Apr 27, 2020

Coal Point is at the tip of the Homer Spit, located on the Kenai Peninsula, 15 miles (24 km) northeast of Seldovia and 5.7 miles (9 km) southeast of Homer, Alaska. The name is an 1881 translation by the U.S. Coast and Geodetic Survey of the Russian “Mys Ugolnoy” or “coal cape” that was first published by Captain Mikhail Tebenkov. The Homer Spit is a sand and gravel beach, about 4.4 miles (7.1 km) long, named in 1904 by R.W. Stone of the U.S. Geological Survey for the village of Homer which was formerly located on the spit.

The spit is formed by the southeastward movement of nearshore sediments, truncated by a submarine trough over 650 feet (200 m) deep that acts as a sediment trap limiting further spit extension. The spit is the supra-tidal portion of a much larger subtidal feature called the Archimandritof Shoals. The shoals were initially formed as a moraine or terminal deposit when Kachemak Bay was still dominated by ancient partially grounded tidewater glaciers. Sand and gravel that now erode from sea cliffs along the Cook Inlet shoreline are suspended by turbulent storm waves, then transported by shallow water wave-induced currents, and eventually deposited where wave energy is attenuated. The Archimandritof Shoals cause large waves to break farther offshore creating a relatively lower energy shoreline where sediment is deposited. Large high energy waves at high tide will cross the shoals and have caused extensive damage to the spit, as well as to the spit road and buildings. The spit is now heavily reinforced with rip rap boulders on the Cook Inlet (south) side.

Changes in the volume of sediment supply can have a large impact on the stability of the spit. Earthquakes generally cause sea cliff subsidence in Cook Inlet that potentially introduces massive volumes of sediment into the nearshore leading to more accretion. Developments such as road building and seawalls or bulkheads built along naturally eroding bluffs can drastically reduce the volume of sediment transported and eventually cause more erosion. Much of the Homer Spit and the adjacent mainland have been altered with bulkheads, boulder rip rap, or some other shore protection structure that prevents or slows erosion to protect houses or other structures. Read more here and here. Explore more of Coal Point here:

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This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2021 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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