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 ...

The ripples on these dunes change over time due ... Namib Dune is between 13 to 17 feet tall and is just one of many sand dunes located in the Bagnold Dunes field situated along the northwestern ...

Thanks to images in publications such as this and all across the internet, we know what to expect when we arrive at Great ...

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 ...

Mr. Cornish showed photographs of ripple-marks mimicking organic forms ... leaving the coarser materials arranged in ridge and furrow. Sand-dunes were built up by the wind on similar principles.

Big waves from hurricanes like Irene in 2011 or Superstorm Sandy last October or even nor’easters like one that lingered in Delaware last week erode shorelines and the beach and dunes ... offshore – ...