Photographs

FIG. 41. Horizontal section through structures formed by stoss-depositional ripples with spurs; fluvial deposits, Colorado River, Grand Canyon National Park, Arizona.

RECOGNITION: These structures are recognizable by their distinctive circular cross-bed traces.  The trend of the ripples was rather irregular, as indicated by the variation in trend of the lines along which the circular cross-bed traces are arranged; one ripple crest is located under the pen.  Displacement of the centers of some of the circular traces suggests that the ripples were asymmetric in profile or were migrating during deposition.