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S-forms by water erosion

Have the s-forms been sculpted by subglacial waters or abrasive action at the base of glaciers? The answer becomes obvious when reading all the publications on the subject. Subglacial waters are likely the cause. In fact, most of the detail publications of the last decades support this thesis. Field observations corroborate laboratory experiments, flash floods, jökulhlaup, and the 2004 tsunami. A scientific approach is legitimized when a comings and goings persist between physical theory, experimentation, and observation of modern events.

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Two contemporary events have reconfirmed that s-forms (sichelwannen, spindle flute, muschelbruch) are sculpted by catastrophic hydraulics:


• Flood of Katherine Gorge in Australia (Baker and Pickup, 1987)

• The 2004 tsunami (Bryant, 2014)

Surprisingly, some geoscientists still ignore hydrodynamic researches on s-forms. There are even faculties that ignore the debate in disfavor of the subglacial water thesis. For their part, hydrodynamic engineers describe this attitude as unacceptable. The notions of turbulent flows and vortices explain all types of s-forms in every detail. So, why some academics resist this idea? The reason is that the model would have two implications:

  1. The troubling aspect of the s-forms is their omnipresence in the territories covered by the ancient ice sheets. Wherever the bedrock outcrops we find these s-forms. This ubiquity suggests that large amounts of water swept under the ice sheets. If we accept that the s-forms are of hydro-catastrophic origin, there is only one step left to explain the genesis of the mysterious drumlins since these two morphologies are closely associated. In addition, several features specific to drumlins are not unlike those of s-forms.

  2. All these s-forms were not erased by subsequent glacial abrasion. When the ice sheet reattached to the bedrock the ice age was over. The water had probably warned down drastically the thickness of the ice. 

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Within the scope of the subglacial water theory... here a 3D animation of these processes under the ice sheet. 

A glaciologist can stipulate that the s-forms could have several origins (polygenic). But so far, those who argue that ancient s-forms have been carved by the abrasive action of glaciers have produced no laboratory experiments, no study of modern occurrences of s-forms and no physical/mathematical models. In short, they produced no scientific publications other than their descriptions of ice age s-forms.

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With a polygenic approach, a glaciologist gives himself the right to insinuate that most of the s-forms of the ice age were the result of glacial abrasion. He does not realize that accepting that vortices can also carve identical shapes implies both; a singularity and an aberration of nature. In my opinion, the proponents of such a position are just unaware of all the publications in favor of the hydrodynamic origin of s-forms.


Before going further on reading this page I invite you to watch this short video of 9 minutes to awaken your intuition.



Omitted cavitation and water hammer, water as such has no abrasive power if not particles of sand and gravel it carries. In subglacial environment the water is overloaded with particles. At high flow the flow becomes turbulent since the slightest obstacle generates vortices or whirlpool. Inevitably vortices and cavitation when combined multiply greatly the erosive power of water.


These vortices dissipate naturally but before fading they will hit the rock digging s-forms for a brief moment:


  • When a vortex strikes the rock obliquely it flares upward, which carves a muschelbruch, a cavity in the form of a mussel.

  • If the vortex brushes the base with a lower angle a flute spindle will appear.

  • When the vortex is deviated laterally by an oblique surface a comma forms will carve a comma.