The following photographs were taken by Katy Rogers of Laramie, Wyoming. They represent some of the best examples I have encountered of oscillatory or symmetrical ripples. They occur in what is probably Cretaceous strata expose at Owl Canyon, Colorado (UTM Zone 13 485184E 4512406 N, WGS84/NAD83). Click on each photograph for a high resolution view.
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Location map from TopoZone. Enter "Owl Canyon" and "Colorado" for the state and TopoZone will take you there!!! |
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View of the outcrop where these oscillatory or symmetrical ripples were found. |
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Oscillatory or symmetrical ripples on a slab surface of sandstone; cigarette for scale. |
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Close-up view of oscillatory or symmetrical ripples. Note the pointed nature of the crest and the more rounded nature of the troughs. This indicates that the facing direction of the slab is upwards and that the surface represents the ripples as they had formed. |
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Oscillatory or symmetrical ripples; dime for scale. |
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Close-up of the oscillatory or symmetrical ripples. Note the rounded nature of the apparent crests and somewhat narrow nature of the apparent troughs. This indicates that the slab surface features are a cast of oscillatory or symmetrical ripples (oscillatory ripple cast). The facing direction here is downward. Dime foe scale. |
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Closer view of the upside-down oscillatory ripple cast. Dime for scale. |
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Side-on or cross-sectional view of oscillatory or symmetrical ripples. The lower bed is the bed upon which the ripples formed whereas the upper bed is one that was deposited upon it and the one the 'cast' the ripples. Note the more pointed nature of the crest and the more rounded nature of the troughs. Facing direction here is upwards. |
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Close-up or another sample of oscillatory or symmetrical ripples in cross-sectional view. The lower tan colored sand layer is the layer upon which the ripples formed. The immediately overlying darker layer is a shale layer that was deposited directly upon the ripples. This was followed by a thin tan colored sand layer, another dark colored sand layer, and then another sand layer. These last layers retain a ripple character due to the compaction of the first shale layer. Note the pointed nature of the crest of the ripples on the lower sand layer and the rounded nature of the troughs. Facing direction is indicated by the up-pointing crests. Dime for scale. |
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Another view lie above but quite as well preserved. Dime for scale. |
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Cross-bedding. |
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Lamination marked by variations in rock color. |
These photographs belong to Katy Rogers[ ivytheplant@msn.com ] and she should be contacted if you wish to make use of such for any purpose.
Comments and suggestions: dockal<at>uncw.edu
Sedimentary Petrology Home Page
University of North Carolina Wilmington http://www.uncw.edu/
This page was last modified on: 09/07/2005