Earth: Dueling theories on dune fields: C-shaped sand mounds persist by colliding or calving.

The article discusses competing theories on sand dunes in the August 7, 2013 issue of the journal "Geophysical Research Letters" by Mathieu Génois of Paris Diderot University in France and colleagues and Stacey Worman of Duke University and colleagues. Topics include studies investigating the structure of barchan corridors in sand dunes, disagreement on the factors limiting dune size, Génois and colleagues collision theory, and Worman and colleagues calving theory.