Scallops on cave walls.

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Re: Scallops on cave walls.

Postby Rane Curl » May 18, 2011 4:17 pm

Scallops as such do not form from water running in thin films down limestone walls, which is what occurs in vadose conditions - other dissolution features can be produced in that situation. Scallops form primarily by dissolving the limestone. Corrasion is likely to remove scallops on limestone, but similar features to scallops occur on granite. An example is at http://agrell.info/erik/grotta/thunder2006/
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Re: Scallops on cave walls.

Postby Roppelcaver » May 19, 2011 11:53 am

In Roppel (90 mile section of Mammoth), scallops are used extensively to map paleo-flows. In a cave that spans across multiple drainage basins, whose boundaries have moved back and forth over geologic history, we use every tool we can to cobble together the role and relationship of the spaghetti bowl of passages (scallops, gradients, intersection morphologies, transported objects (formations), etc.). But scallops are the most useful.

The Black River Complex has the most evidence of these moving basin boundaries, and as you descend through the levels of canyons, flow directions are often reversed from the one above. In fact, in several canyons, the upper half of the passage exhibits flow in one direction, while the lower the opposite. This is quite fun, and makes for a good puzzle in the effort to understand the paleohoydrology of Roppel. I always figured that you could get an idea of the relative length of time water spent flowing at certain elevations based on the level of scallop replacement that has occurred -- the lower parts show no evidence of the previous flow, whereas the upper parts look more confused with conflicting scallop directions.

In Roppel, we have three major basins whose boundaries intersect -- Pike spring (Flint Ridge), Lawler Blue Hole (Fisher Ridge), and Turnhole Spring (Joppa Ridge). In the 70s, we called this the center of the hydrologic universe, and we spent a lot of time dileniating the basin boundaries (with oversight and support from Jim Quinlan, Mammoth Cave National Park).

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Re: Scallops on cave walls.

Postby Rane Curl » Aug 3, 2011 12:19 am

The "confusion" over which is the steep side is due to not being careful in describing what you are describing.... If one is describing the *crest* of a scallop, the steep side is downstream. If one is describing the *hollow* of a scallop, the steep side is upstream. But saying "the steep side faces downstream" avoids that confusion.
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Re: Scallops on cave walls.

Postby szifon » Dec 14, 2011 8:58 am

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