Kinneyia, a fossil hydrodynamic instability

Dr Lucas Goehring (Nottingham Trent University)

Frank Adams 1,

Microbial mats from over half the history of the Earth have been fossilised with intriguing ripple patterns on them, a few millimetres wide.  We show that these features can be caused by a Kelvin-Helmholz-like instability, of the flow of water over a
 viscoelastic fluid like the protein-rich slimy matrix of a microbial colony.  By a combination of analogue experiments, and linear stability analysis, we show that the conditions for the formation of such small-scale ripples should be incredibly generic, and also develop a scaling analysis for their wavelength selection.  This allows us to use the structure of Kinneyia as an indicator of the growth conditions of algal mats in the deep precambrian.

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