I'm standing in the trough between two big ripples. I am almost six feet tall when wearing my hiking boots. I estimate the trough-to-crest height at 34 feet (10m).Compare this to ripples you might see at the beach, or at the edge of the river. I think I read that fast-flowing water had to be 200-300 feet deep to create ripples of this size.
Geo-tagging is approximate.

This picture was made possible by Ralph Tripod, my personal photographic assistant. His devotion to duty is equally strong on crests and troughs.