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EUREKA DUNES Text and photos by Mary DeDecker Educational Bulletin 87.3 A publication of the Education Foundation of the Desert Protective Council, Inc. |
| Sand Mountain from northeast. A sand dune system is an ecological island. Its shape is determined by the effect of nearby land masses on the prevailing winds. Its location indicates an obstacle to the air flow. The Eureka Dunes are located in the southeast curve of Eureka Valley near the convergence of Last Chance Mountains and the Saline Range. They are only about 6 air miles from the northwest corner of Death Valley National Monument and 25 miles east of Big Pine, California. The Eureka Dunes are composed of a massive sand mountain 664 feet high, and a series of transverse dunes about a third as high. The sand mountain, called a seif by Gattung, et al, occupies a triangular area of approximately 4 square miles at the north end. The lesser dunes to the southeast occupy 5 square miles. The dividing line runs southwest from a point about 0.6 mile south of the northeast corner to a point about midway on the western boundary. A sand sheet surrounds the dunes on all sides except on the playa and where the clay deposits of the Pleistocene lakebed are exposed. It is most extensive on the east side. The playa, oblong in shape, approximates the area of the dunes in size. It extends westward from the northwest corner of the large dune. On rare occasions it is filled with water and is deceptively inviting . . . the shallow blue lake reflecting the mountains and sky, a beautiful sight. Beware of driving too close, however. More than one vehicle has become stuck in the sticky mud of tracks which run that way. According to Gattung, et al, who studied the dune systems of the Northern Mojave, the seif is positioned in line with the strongest prevailing winds, while the rest of the dune system was formed by more complex wind patterns.
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A unique feature of the sand mountain is its
hydrology. Unlike many dune systems, the Eureka Dunes are not within the rain
shadow of a prominent mountain barrier. Being located in close proximity to the
west wall of the precipitous Last Chance Mountains, it receives rain or snow
from any storm which gathers along that mountain crest. The precipitation does
not run off but gradually percolates downward and outward throughout the dry
summer months. The seif is an unusual form of reservoir capable of storing a
great amount of water. It furnishes a reliable water supply all around its
perimeter. The result is an unusually rich and abundant flora, along with the
fauna dependent on it. Over 50 species of plants occur there. The isolation of
this sand island has allowed three endemic plants to develop. There are also
endemic insects adapted to dune life. The sand is pale gold or cream color, depending on light conditions. Gattung, et al, states that it is predominately quartz (silicon dioxide), and that the particulates are of larger size than those of the Saline Panamint, or Death Valley dunes. The darker grains, which often outline the wave patterns, are magnetite or other minerals, mostly of igneous origin. Those who climb the high ridges may experience the vibration of a "singing dune". The cascading sand under certain conditions emits a peculiar sound similar to that of a bass violin. This is said to depend on the form and position of sand particles, and probably on the moisture content, too. Only a few dunes in the country are known to do this. The most noted of the endemic plants is the Eureka dunegrass (Swailenia alexandrae). It is a monotypic genus, discovered by Annie Alexander, an intrepid collector, in May 1949. She and Louise Kellog were on a collecting expedition in that remote part of California when she found this strange new grass. It was referred to Jason R. Swallen at the U.S. |