Two different types of ripple marks exposed at the same place (but formed at different times) near the summit of Ketobe Knob, Utah, USA.
On the left, "the crests and troughs of the ripples are relatively straight and continuous, leading to the name 2D current ripples". "As current velocity increases, the troughs become more bowl-like and discontinuous, and the crests become highly curved and sinuous. This latter type of ripple is known as a 3D current ripple." (UGA Stratigraphy Lab)

Reference
UGA Stratigraphy Lab, Layering and Unidirectional Flow Bedforms, http://strata.uga.edu/4500/bedforms/bedforms.html