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The scallops made by running water in a cave on the walls.....
how do you read them,....which way indicates the direction the water was following at one point?

shottheradio wrote:The scallops made by running water in a cave on the walls.....
how do you read them,....which way indicates the direction the water was following at one point?

I don't know that you can, since at the point where the scallops are formed, the water is turbulent, not laminar flow. I would think the shape of the scallops is as dependent on the composition of the rock as on the overall direction of the water, which likely would be in constant change along the walls.

deep end to shallow end is the direction i thought. but i have common sence and not a payed education. so a book worm might disagree

I do know the faster the water is flowing. the smaller the scallops usually are.
I am just not sure about the direction of the grade.

Scallops are an excellent indicator of water flow!

Flow direction is indicated by where the scallop "points". The steep side is downstream. Imagine that the flowing water "erodes" the side that it hits and flattens it the most, making the scallop point downstream.

Scallop size is inversely-proportional to flow velocity. Small scallops indicate fast-moving water, large scallops indicate slow moving water. Scallops can be several feet in length or millimeters in length.

Keep in mind that the flow which formed the scallops that you are looking at is from the water at the passage walls - the water flows faster towards the middle of the passage. Also, more recent scallops can be formed on top of older scallops (from different flow conditions), or may complete destroy old scallops - floodwater scallops could mask "normal" flow scallops.

Interestingly, it's the viscosity of the fluid which determines the parameters of the scallops, not the solid. For instance, scallops form on the walls of ice caves - the "rock" is ice, and the fluid is air!

Rane Curl wrote the "classic" paper on interpreting cave scallops, but it's a tough read. In short, it is possible to determine flow velocity quantitatively from scallop measurements, and possible to determine discharge with the addition of passage volume.

very nice answer thank you,...
so you basically read them the same way you would sand of silt on a river bed. The steep side is up stream,.. and the more graduale incline is down stream?
thank you.

shottheradio wrote:The steep side is up stream,.. and the more graduale incline is down stream?

You have it backwards. The steep side is downstream, the gradual side is upstream.

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ah,... gotcha gotcha.
thanks

I have a paper in prep about scallops. I did it on my last years science project and made second place at state in New Mexico. if you want a copy just pm me. thanks

Alfred Bogli, NSS3918, a Swiss geologist, wrote extensively on scallops and also mixed water corrosion. Much of his work on karst and scallops was done in Holloch.

driggs wrote:You have it backwards. The steep side is downstream, the gradual side is upstream.

I always thought it was the other way round, as per Weevil.

http://www.britannica.com/ebc/article-49695 says: Among the most significant of the solutional sculpturings are the small scooplike depressions known as scallops. Scallops vary in size from a few centimetres to more than one metre. They are asymmetrical in cross section, having a steep wall on the upstream side and a gentler slope on the downstream side. Scallops thus provide information as to the direction of water flow in passages that have been dry for hundreds of thousands of years. The size of a scallop is inversely proportional to the flow velocity of water in the passage. As a consequence, scallops serve not only as paleo-direction indicators but also as paleo-flow meters. Scallops that are a few centimetres wide indicate flow velocities on the order of a few metres per second. The largest scallops, those that are more than one metre wide, indicate flow velocities of a few centimetres per second.

ian mckenzie wrote:They are asymmetrical in cross section, having a steep wall on the upstream side and a gentler slope on the downstream side.

Marjorie Sweeting (AKA the "mother of karst"), on page 144 of her 1973 book Karst Landforms, says

A section taken through the crests [of a scallop] transverse to the flow direction always shows that the downstream slope is steeper than the upstream.

Chapter 11 of Art Palmer's Geological Guide to Mammoth Cave National Park contains very explicit photos and diagrams (similar to my crude ASCII diagram above), and he states:

The direction of the water flow that formed the scallops is indicated by their steep sides, which face in the downstream direction.

Lauritzen and Lundberg's Solutional and Erosional Morphology, chapter 6.1 in Speleogenesis, says:

The longitudinal profile of scallops and flutes always has the steepest side facing downstream.

OK, I even dug out Rane Curl's "classic" paper from the 1974 NSS bulletin, Deducing Flow Velocity in Cave Conduits from Scallops... Rane introduces things by talking about "turbulent jet flow" and then referring to a diagram, which shows the steep side on the downstream side.

Convinced yet?

driggs wrote:
OK, I even dug out Rane Curl's "classic" paper from the 1974 NSS bulletin, Deducing Flow Velocity in Cave Conduits from Scallops... Rane introduces things by talking about "turbulent jet flow" and then referring to a diagram, which shows the steep side on the downstream side.

Convinced yet?

I think you wrote that incorrectly and really meant the steep side is on the upstream side and faces downstream. Referring to the diagram, the steep side is directly below the circle with the "1" inside and the tail end of the arrow pointing right or downstream. I am puzzled by Sweeting's explanation which seems backwards from the rest.

driggs wrote:Convinced yet?

No.

Speleogenesis says: "Scallops form patterns on the walls of caves and in streambeds and may be used to determine direction of flow of turbulent water, since they are steeper on the upstream side."

Strange that so many references disagree. But I agree that the upstream side is steeper. It's like a little eddy or rapid. Water goes off an edge, falls, digs a hole then flattens out.