The difference is a matter of size: ripples are small ridges of sand with a height (amplitude) typically less than 4 cm and wave lengths (crest to crest) less than 60 cm, while dunes have the same ...

Sand deposition, accretion ... symmetrical to asymmetrical dune ridges. The morphology of foredunes is varied but they can be classified into three main types: incipient foredunes, established ...

Inland, sand dunes rise almost 200 feet in a series of ridges, blowouts and valleys, while wetlands fill depressions between dune ridges. The park is home to over 1,100 flowering plant species and ...

A star dune is a type of sand dune that has at least three ridges coming from a central peak, which gives it a star-like shape when viewed from above, according to NASA's Earth Observatory.

This story appears in the November 2012 issue of National Geographic magazine. I got my first lesson in the physics of sand dunes in 1998 on an expedition into the Sahara. In order to take aerial ...

The Lut sand-seas are amongst the best developed active dune fields in the world, displaying a wide variety of dune types (crescentic ridges, star dunes, complex linear dunes, funnel-shaped dunes) ...

This giant sand dune in southern Spain is about 98 feet high and 656 feet wide, making it one of Europe's largest sand dunes. What is perhaps even more fascinating is what hides beneath it.

Primary vegetation gives stability to the sand dune which, in turn, traps sand. Wind is then deflected over the ridge and vegetation, creating shelter for larger plants to grow and establish.

The most popular attraction on Nags Head (aside from the ocean) is Jockey's Ridge State Park, home to the tallest living sand dune on the Atlantic coast. Climb to the top and tap into your ...