Ma-le’l Dunes, Humboldt Bay

Ma-le’l Dunes, Humboldt Bay

by | Mar 14, 2022

Ma-le’l Dunes are a National Natural Landmark situated between the Mad River Slough and the Pacific Ocean at the base of the Samoa Peninsula that partially encloses the northern part of Humboldt Bay, about 1 mile (1.6 km) north of Manila and 3.5 miles (5.6 km) west of Arcata, California. The Ma-le’l Dunes are divided into northern and southern sections. The northern portion is part of Humboldt Bay National Wildlife Refuge managed by the U.S. Fish and Wildlife Service, and the southern portion of Ma-le’l is managed by the Bureau of Land Management. The dunes are named after a historical Wiyot tribal village or seasonal camp located within the dunes. Humboldt Bay was named after the German naturalist Alexander von Humboldt. The bay is 14 miles (23 km) long and 4.5 miles (7 km) across at its widest point and is the second-largest enclosed bay in California. The structural geology of the coastal fringe north of Cape Mendocino is driven mostly by interactions among the oceanic Gorda and Pacific plates, and the continental North American plate, collectively characterized as the Mendocino Triple Junction. The Coast Ranges result from deformation caused by the ongoing accretion and subduction of rock beneath the continental margin along with northward movement associated with the San Andreas fault system. The Coast Ranges are comprised mostly of accreted Mesozoic and Cenozoic rocks, on the geological time scale, of the Franciscan Complex dominated by greywacke sandstones, shales, and conglomerates that have experienced low-grade metamorphism. These rocks are overlain by marine and fluvial sediments that have been uplifted. Fluvial terraces are well developed along the major rivers including the Mad, Eel, Van Duzen, and Mattole Rivers. Marine terrace deposits include well-sorted, coarse granule-sized gravels, cobble berms, and dune sand deposits preserved on uplifted Holocene and Pleistocene marine platforms. The Ma-le’l Dunes lie in the northern portion of a coastal barrier sand dune complex that probably migrated up the marine shelf with rising sea levels after the Last Glacial Maximum, reaching its current location about 7,000 years ago. The dunes consist of quartz and feldspars carried to the coast by rivers and of basalt eroded from coastal headlands. The coastal dunes are formed from the deposition of sand transported along the coast by nearshore wave-generated currents. In summer during relatively calm conditions, predominantly southward currents deposit sand on beaches. In winter during high energy stormy conditions, the currents are predominantly northward and cause beach erosion.

Wiyot people have lived around Humboldt Bay for thousands of years and used the dunes of the north and south spits for fishing and hunting. The dunes were also an area visited annually for gathering huckleberries. The Wiyot traditional homeland ranged from Mad River in the north through Humboldt Bay to the lower Eel River in the south, and they mostly inhabited the coastal fringe of dunes and tidal marshes. The Wiyot were among the last natives in California to encounter white settlers since Spanish missions extended only as far north as San Francisco Bay. In 1806, Captain Jonathan Winship is credited with the first recorded ship entry into Humboldt Bay while employed by the Russian-American Company engaged in the maritime fur trade, but Russian fur traders mostly by-passed the bay in search of better sea otter habitat. By the mid-1800s, gold and timber attracted Euro-American settlers to the area seeking to make their fortune. Josiah Gregg and an exploring party arrived at Humboldt Bay in 1849 by crossing the Coast Ranges. Subsequent to their return to San Francisco, the news of the discovery prompted several ships to sail north and in 1850, Lieutenant Douglass Ottinger on the Laura Virginia became the first American vessel to enter Humboldt Bay. In 1853, Fort Humboldt was established by the U.S. Army under the command of Brevet Lieutenant Colonel Robert C. Buchanan of the U.S. 4th Infantry Regiment as a buffer between the Wiyot and gold-seekers and settlers. Competition for land and resources led to violent clashes with the Wiyot, and along with exposure to foreign diseases such as smallpox and influenza, their population was decimated. The bay became a major transportation hub for the logging industry facilitated by railroads. Settlements around the bay grew into towns and marshy areas surrounding the bay were drained and diked for cattle pasture. Several homesteads were located in the dunes and European beachgrass was planted to stabilize the shifting sands. Sand mining was conducted in the dunes until the 1990s. Conservation of the dunes began in the 1940s, and in 1976, Hortense and William Lanphere donated land in the dunes to The Nature Conservancy establishing the Lanphere-Christensen Dunes Preserve. In 1997, the preserve became part of the Humboldt Bay National Wildlife Refuge, and in 2004, the Ma-le’l Dunes were added to the refuge creating the Lanphere Ma-le’l Dunes.

The planting of European beachgrass on west coast dunes was common in the first half of the 20th century. It was first introduced at Golden Gate Park in San Francisco in the late 1800s as a means to stabilize the constantly shifting sand. Thousands of acres of west coast sand dunes were stabilized during this period with the majority located along the Oregon coast. As a result, the Oregon and Washington coastlines are now largely lacking intact native dune plant communities. The introduction and spread of European beachgrass on the North Spit dunes of Humboldt Bay have been well studied since 1901. European beachgrass is a better sand accumulator than the native dune grass and creates a higher, steeper foredune that decreases the aeolian transport of sand to interior dunes. Perhaps the most significant impact is its ability to displace entire native plant communities. Once occurring along most major dune systems of the west coast north of Monterey, California, the native dune grass community is now restricted to Point Reyes and Humboldt Bay. European beachgrass currently or potentially impacts six federally listed endangered plants that occur on coastal dunes of California, and is also detrimental to the threatened western snowy plover, a shorebird that nests in open areas on the strand. Dense stands of European beachgrass directly displace snowy plover nesting sites and enhance cover for predators, subsequently decreasing nesting success. Coastal dune restoration has recently focused on the removal of these invasive plants. Although interest in controlling European beachgrass began about 1980, large-scale implementation of control efforts did not start until the 1990s. Controls now used include manual, mechanical, and chemical methods used alone or in combination. Manual removal of non-native plants was carried out from 2005 to 2010 at the Ma-le’l Dunes, however, European beachgrass is now so widespread on the U.S. west coast that its eradication is not practical unless a more economic means of control is found. Read more here and here. Explore more of the Ma-le’l Dunes here:

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About the background graphic

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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