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 ...

Sea-level rise is threatening San Francisco’s shores. In February, the city began vegetating the sand dunes as part of its ...

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 ...

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.

Scientists have long questioned whether the ridges might represent the remnants ... “The structures don’t look like sand dunes,” Manga said. “They don’t look like an impact crater.

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 ...