Panamint Valley and its Sand Dunes

 
Panamint Valley is a 100 mile long, 2 to 10 mile wide depression sandwiched between the Panamint Range on the east and the Argus and Slate ranges on the west. It's northern end is bounded by hills that back the unique Panamint sand dunes. Earthquakes have uplifted the mountains and dropped the valley floor along major faults as the earth's crust stretches here. The great Pleistocene alluvial fans just south of Ballarat are evidence of this continuing upheaval where the fault scarp is over 100' high.

      During the Pleistocene epoch (1.8 million to 10,000 yar ago), Panamint Valley was filled with one of a chain of lakes extending from Mono Basin (north of Mammoth at Lee Vining), throughOwn Lake (near Lone Pine), down to China Lake (at Ridgecrest), through Searles and Panamint lakes, and finally to Death Valley, the lowest lake of the chain. These lakes were fed by torrents of water as the great Sierra Nevada glaciers melted. Five glacial epochs have been identified, the last two being the Tahoe (75,000 years ago) and the Tioga (22,000 years ago). Between these epochs were dry periods lasting thousands of years. As the valley dropped between the faults that defined its east and west margins, it filled with lake sediments during the wet periods and with alluvium during the dry periods. This drop-and-fill action happened over and over again.

      An alluvial fan now divides the valley into two basins, each with its own playa (dry mud flat covered with water in the wet season). The southern playa (south of Ballarat) is about 1,040 feet elevation: the northern one (east of Panamint Springs) is about 1,540 feet, and since the fan is 1,710 feet high, the northern lake cannot drain south until it is 170 feet deep. (not in our lifetime!)

      The most prominent shorelines of ancient Lake Panamint developed about 23,000 years ago coincided with the Tioga glaciation. Shorelines of the ancient lake are as high as 1,820 feet near Panamint Springs. Assuming the valley floor hasn't dropped and the mountains haven't risen in the last 23,000 years, the lake was 280 feet deep east of Panamint Springs providing lakefront peoperty for the resort (had it existed then), but the fishing was probably questionable. Diatoms (algae with shells of silica) found in the old lake beds near Panamint Springs indicate that the lake was quite warm and salty at that time.

     The Panamint Valley sand dunes are located on a large, sloping alluvial fan at the north end of the valley. What we recognize as the "dunes" today is only a part of a larger dune field. The dune field includes ancient, now stabilized, dunes that cover about 3 miles north-to-south and about 1.2 miles east-to west. On the northern end of this field today's dunes rise about 200 feet.

      An often asked question is: Why are the dunes located where they are and how did they develop?

      The answer is: wind. During winter storms, strong winds rush up Panamint VAlley. As they pass over the alluvial fans and dry playas, they pick up small particles of sand, mostly quartz and feldspar.

      As the wind bumps against the northern wall of the valley, it loses its speed and drops the sand it is carrying, thus creating the dunes. The finer particles from the playas continue to rise and are swept over the north rim of the valley. Since the wind can move only certain speeds, the sand grains dropped on the dunes are of similar size.

      One Death Valley geology book said sand from Panamint Valley helped create the dunes in Death Valley. The physical laws of how dunes are made makes this supposition impossible.

      These dunes are geologically young; During glacial periods, the valley floor was filled with a lake, and there would have been enough moisture to sustain vegetation on the remaining slopes. During these periods, the ancestral dunes stabilized, and vegetation grew on them.

      The north playa was again full of water as recently as 10,000 years ago, and evidence suggests the lake did not completely dry up until about 6,000 years ago. After the lake shrank, moisture in the air decreased, and plants on the alluvial fans died out. For the past 5,000 years, the valley has been dry enought to expose sand particles to the wind as it rushes up the trough of the valley. The dunes began to grow again.

      The ancestral dunes, the dune field upon which the new dunes are growing, were"young" 23,000 years ago or more and grew during the dry periods between the pluvial (wet) epochs.

      The top few inches of sand on the dunes is dry year round (except during a rain storm), but it is moist lower down. Large, healthy bushes grow on the surface, and the remains of desert annuals are abundant.

      There is evidnce that humans inhabited the dune area as far back as 7,000 BC, and recent research indicataes this date may be pushed back 3 times as far. Shoshone Indians, or their ancestors, probably lived in the area during wetter periods when vegetation was more abundant.

      The dunes are within Death Valley National Park. An unimproved road, for high-clearance vehicles only, goes within two and one-half miles of them. Always take water and appropriate clothing when hiking the desert, and tell someone where you are going.

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