Symmetric Ripples

If the ripples are symmetric, on the other hand, the flows must have moved back and forth, like waves in an ocean. This oscillatory motion produces a ripple with a fairly pointed crest, but a more gentle trough.  When these ripples aggrade, they produce wave-ripple laminae and hummocky cross stratification. 

What happens if symmetric ripples have been overturned?

Because of their distinct shape, with pointy crests and gentle troughs, symmetric ripples can be used as an indicator of stratigraphic top.