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The Killpecker sand dunes of the Red Desert in southwestern Wyoming. Jockey's Ridge State Park – on the Outer Banks, North Carolina. The Great Dune found in Cape Henlopen State Park in Lewes, Delaware. Oregon Dunes National Recreation Area near Florence, Oregon, on the Pacific Coast. Bruneau Dunes State Park – Owyhee Desert, Idaho
By nature, ergs are very active. Smaller dunes form and migrate along the flanks of the larger dunes and sand ridges. Occasional precipitation fills basins formed by the dunes; as the water evaporates, salt deposits are left behind. Individual dunes in ergs typically have widths, lengths, or both dimensions greater than 500 m (1,600 ft). [2]
As barchan dunes migrate, smaller dunes outpace larger dunes, catching-up the rear of the larger dune and eventually appear to punch through the large dune to appear on the other side. The process appears superficially similar to waves of light, sound, or water that pass directly through each other, but the detailed mechanism is very different.
Cross-bedding is formed by the downstream migration of bedforms such as ripples or dunes [3] in a flowing fluid. The fluid flow causes sand grains to saltate up the stoss (upstream) side of the bedform and collect at the peak until the angle of repose is reached. At this point, the crest of granular material has grown too large and will be ...
Transporting iron ore from a remote mine in the Sahara Desert to the Atlantic coast, Mauritania’s Train du Desert rumbles 437 miles (704 kilometers) across one of the planet’s least inhabited ...
Dunes: A dune is a large pile of wind-blown material, typically sand or snow. As the pile accumulates, its larger surface area increases the rate of deposition in a positive feedback loop until the dune collapses under its own weight. This process causes dunes to move in the direction of the wind over time. [6] [7] Death Valley Mesquite Flats ...
Don’t call it a comeback. The hummingbirds are on their way. If you plan on feeding them or simply want to avoid getting attacked for being too close to their nest, here’s what you need to know.
The seas of Texas were home to massive reefs made of spined brachiopods jumbled together. [37] Seas that had previously covered Kansas, New Mexico and Texas began drying up and left behind salt deposits. The inner portions of the western United States had a hot dry climate. Sand dunes were common throughout the country. [36]