Of course, some ripples are formed in wind, but they grow also in water currents on beaches or on river beds, even on the ocean floor four kilometres down (no wind there). Certainly the physics of the process is still argued about in terms of sheer stress, bedload, friction, turbulence and so on, but the nature of the two media is never in doubt.
We can observe ripple marks forming in both air and water. Steve Connor should try snorkeling with a face mask off his nearest beach. But ripples would grow equally well in currents of beer or Chateauneuf-du- Pape.
ROBIN G. C. BATHURST
Department of Earth Sciences
Liverpool UniversityReuse content