Abstract
Sand is blown across beaches and deserts by turbulent winds. This seemingly chaotic process creates two dominant bedforms: decametre-scale dunes and centimetre-scale ripples, but hardly anything in between. By the very same process, grains are constantly sorted. Smaller grains advance faster, while heavier grains trail behind. Here, we argue that, under erosive conditions, sand sorting and structure formation can conspire to create distinct bedforms in the ‘forbidden wavelength gap’ between aeolian ripples and dunes. These so-called megaripples are shown to co-evolve with an unusual, predominantly bimodal grain-size distribution. Combining theory and field measurements, we develop a mechanistic understanding of their formation, shape and migration, as well as their cyclic ageing, renewal and sedimentary memory, in terms of the intermittent wind statistics. Our results demonstrate that megaripples exhibit close similarities to dunes and can indeed be mechanistically characterized as a special type of (‘reptation’) dune.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$209.00 per year
only $17.42 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Bagnold, R. A. The Physics of Blown Sand and Desert Dunes (Methuen, London, 1941).
Wilson, I. G. Aeolian bedforms—their development and origins. Sedimentology 19, 173–210 (1972).
Pye, K. & Tsoar, H. Aeolian Sand and Sand Dunes (Springer, Berlin, 2009).
Durán, O., Claudin, P. & Andreotti, B. Direct numerical simulations of aeolian sand ripples. Proc. Natl Acad. Sci. USA 111, 15665 (2014).
Andreotti, B., Claudin, P. & Pouliquen, O. Aeolian sand ripples: Experimental study of fully developed states. Phys. Rev. Lett. 96, 028001 (2006).
Manukyan, E. & Prigozhin, L. Formation of aeolian ripples and sand sorting. Phys. Rev. E 79, 031303 (2009).
Kroy, K., Sauermann, G. & Herrmann, H. J. Minimal model for sand dunes. Phys. Rev. Lett. 88, 054301 (2002).
Andreotti, B., Claudin, P. & Douady, S. Selection of dune shapes and velocities part 1: Dynamics of sand, wind and barchans. Eur. Phys. J. B 28, 321–339 (2002).
Sauermann, G., Kroy, K. & Herrmann, H. J. Continuum saltation model for sand dunes. Phys. Rev. E 64, 031305 (2001).
Andreotti, B., Claudin, P. & Pouliquen, O. Measurements of the aeolian sand transport saturation length. Geomorphology 123, 343–348 (2010).
Lämmel, M. & Kroy, K. Analytical mesoscale modeling of aeolian sand transport. Phys. Rev. E 96, 052906 (2017).
Lapotre, M. G. A. et al. Large wind ripples on Mars: A record of atmospheric evolution. Science 353, 55–58 (2016).
Sharp, R. P. Wind ripples. J. Geol. 71, 617–636 (1963).
Yizhaq, H., Isenberg, O., Wenkart, R., Tsoar, H. & Karnieli, A. Morphology and dynamics of aeolian mega-ripples in Nahal Kasuy, southern Israel. Isr. J. Earth Sci. 57, 149–165 (2009).
Ellwood, J. M., Evans, P. D. & Wilson, I. G. Small scale aeolian bedforms. J. Sediment. Res. 45, 554–561 (1975).
Tsoar, H. Grain-size characteristics of wind ripples on a desert seif dune. Geogr. Res. Forum 10, 37–50 (1990).
Sørensen, M. in The Fascination of Probability, Statistics and their Applications: In Honour of Ole E. Barndorff-Nielsen (eds Podolskij, M. et al.) 1–13 (Springer International, Cham, 2016).
Sakamoto-Arnold, C. M. Eolian features produced by the December 1977 windstorm, southern San Joaquin Valley, California. J. Geol. 89, 129–137 (1981).
Ackert, R. The origin of isolated gravel ripples in the western Asgard Range, Antarctica. Antarct. J. 24, 60–62 (1989).
Selby, M. J., Rains, R. B. & Palmer, R. W. P. Eolian deposits of the ice-free Victoria Valley, Southern Victoria Land, Antarctica. New Zeal. J. Geol. Geophys. 17, 543–562 (1974).
Yizhaq, H., Katra, I., Kok, J. F. & Isenberg, O. Transverse instability of megaripples. Geology 40, 459–462 (2012).
Qian, G., Dong, Z., Zhang, Z., Luo, W. & Lu, J. Granule ripples in the Kumtagh Desert, China: Morphology, grain size and influencing factors. Sedimentology 59, 1888–1901 (2012).
Gillies, J. A., Nickling, W. G., Tilson, M. & Furtak-Cole, E. Wind-formed gravel bed forms, wright valley, Antarctica. J. Geophys. Res. Earth Surf. 117, F04017 (2012).
Brugmans, F. Wind ripples in an active drift sand area in the Netherlands: A preliminary report. Earth Surf. Proc. Land. 8, 527–534 (1983).
Milana, J. P. Largest wind ripples on Earth? Geology 37, 343–346 (2009).
de Silva, S., Spagnuolo, M., Bridges, N. & Zimbelman, J. Gravel-mantled megaripples of the Argentinean Puna: A model for their origin and growth with implications for Mars. Geol. Soc. Am. Bull. 125, 1912–1929 (2013).
Bridges, N., Spagnuolo, M., de Silva, S., Zimbelman, J. & Neely, E. Formation of gravel-mantled megaripples on Earth and Mars: Insights from the Argentinean Puna and wind tunnel experiments. Aeolian Res. 17, 49–60 (2015).
Blom, A. & Parker, G. Vertical sorting and the morphodynamics of bed form–dominated rivers: A modeling framework. J. Geophys. Res. Earth Surf. 109, F02007 (2004).
Jerolmack, D. J., Mohrig, D., Grotzinger, J. P., Fike, D. A. & Watters, W. A. Spatial grain size sorting in eolian ripples and estimation of wind conditions on planetary surfaces: Application to meridiani planum, Mars. J. Geophys. Res. 111, E12S02 (2006).
McKenna Neuman, C. & Bédard, O. A wind tunnel investigation of particle segregation, ripple formation and armouring within sand beds of systematically varied texture. Earth Surf. Proc. Land. 42, 749–762 (2017).
Anderson, R. S. & Bunas, K. L. Grain size segregation and stratigraphy in aeolian ripples modelled with a cellular automaton. Nature 365, 740–743 (1993).
Makse, H. A. Grain segregation mechanism in aeolian sand ripples. Eur. Phys. J. E 1, 127–135 (2000).
Shiryayev, A. N. in Selected Works of A. N. Kolmogorov: Volume II Probability Theory and Mathematical Statistics (ed. Shiryayev, A. N.) 281–284 (Springer Netherlands, Dordrecht, 1992).
Yizhaq, H., Katra, I., Isenberg, O. & Tsoar, H. Evolution of megaripples from a flat bed. Aeolian Res. 6, 1–12 (2012).
Katra, I., Yizhaq, H. & Kok, J. F. Mechanisms limiting the growth of aeolian megaripples. Geophys. Res. Lett. 41, 858–865 (2014).
Seppälä, M. & Lindé, K. Wind tunnel studies of ripple formation. Geogr. Ann. A 60, 29–42 (1978).
Fischer, S., Cates, M. E. & Kroy, K. Dynamic scaling of desert dunes. Phys. Rev. E 77, 031302 (2008).
Goossens, D. Aeolian dust ripples: Their occurrence, morphometrical characteristics, dynamics and origin. CATENA 18, 379–407 (1991).
Lorenz, R. D. & Valdez, A. Variable wind ripple migration at Great Sand Dunes National Park and Preserve, observed by timelapse imaging. Geomorphology 133, 1–10 (2011).
Yizhaq, H. & Katra, I. Longevity of aeolian megaripples. Earth. Planet. Sci. Lett. 422, 28–32 (2015).
Kroy, K., Sauermann, G. & Herrmann, H. J. Minimal model for aeolian sand dunes. Phys. Rev. E 66, 031302 (2002).
Musa, R. A., Takarrouht, S., Louge, M. Y., Xu, J. & Berberich, M. E. Pore pressure in a wind-swept rippled bed below the suspension threshold. J. Geophys. Res. Earth Surf. 119, 2574–2590 (2014).
Isenberg, O. et al. Megaripple flattening due to strong winds. Geomorphology 131, 69–84 (2011).
Williams, S. H., Zimbelman, J. R. & Ward, A. Large ripples on Earth and Mars. In Proc. 33rd Annual Lunar and Planetary Science Conference 1508 (NASA, 2002).
Zimbelman, J. R., Williams, S. H. & Johnston, A. K. Crosssectional profiles of sand ripples, megaripples, and dunes: a method for discriminating between formational mechanisms. Earth Surf. Proc. Land 37, 1120–1125 (2012).
Zimbelman, J. R. Transverse aeolian ridges on Mars: First results from hirise images. Geomorphology 121, 22–29 (2010).
Groh, C., Wierschem, A., Aksel, N., Rehberg, I. & Kruelle, C. A. Barchan dunes in two dimensions: Experimental tests for minimal models. Phys. Rev. E 78, 021304 (2008).
Kroy, K. & Guo, X. Comment on “relevant length scale of barchan dunes”. Phys. Rev. Lett. 93, 039401 (2004).
Franklin, E. M. & Charru, F. Subaqueous barchan dunes in turbulent shear flow. Part 1. Dune motion. J. Fluid. Mech. 675, 199–222 (2011).
Beck, C. Statistics of three-dimensional lagrangian turbulence. Phys. Rev. Lett. 98, 064502 (2007).
Finkel, H. J. The barchans of southern Peru. J. Geol. 67, 614–647 (1959).
Sauermann, G. The shape of the barchan dunes of Southern Morocco. Geomorphology 36, 47–62 (2000).
Fryberger, S., Hesp, P. & Hastings, K. Aeolian granule ripple deposits, Namibia. Sedimentology 39, 319–331 (1992).
Hesp, P. A. & Hastings, K. Width, height and slope relationships and aerodynamic maintenance of barchans. Geomorphology 22, 193–204 (1998).
Hersen, P., Douady, S. & Andreotti, B. Relevant length scale of barchan dunes. Phys. Rev. Lett. 89, 264301 (2002).
Andreotti, B., Fourrière, A., Ould-Kaddour, F., Murray, B. & Claudin, P. Giant aeolian dune size determined by the average depth of the atmospheric boundary layer. Nature 457, 1120–1123 (2009).
Rasmussen, K. R., Valance, A. & Merrison, J. Laboratory studies of aeolian sediment transport processes on planetary surfaces. Geomorphology 244, 74–94 (2015).
Ping, L., Narteau, C., Dong, Z., Zhang, Z. & Courrech du Pont, S. Emergence of oblique dunes in a landscape-scale experiment. Nat. Geosci. 7, 99–103 (2014).
Hersen, P., Andersen, K. H., Elbelrhiti, H., Andreotti, B., Claudin, P. & Douady, S. Corridors of barchan dunes: Stability and size selection. Phys. Rev. E 69, 011304 (2004).
Hugenholtz, C. H., Barchyn, T. E. & Favaro, E. A. Formation of periodic bedrock ridges on Earth. Aeolian Res. 18, 135–144 (2015).
Anderson, R. S. A theoretical model for aeolian impact ripples. Sedimentology 34, 943–956 (1987).
Larsen, S. E., Jørgensen, H. E., Landberg, L. & Tillman, J. E. Aspects of the atmospheric surface layers on Mars and Earth. Boundary Layer Meteorol. 105, 451–470 (2002).
Sullivan, R. et al. Aeolian processes at the Mars Exploration Rover Meridiani Planum landing site. Nature 436, 58–61 (2005).
Claudin, P. & Andreotti, B. A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples. Earth. Planet. Sci. Lett. 252, 30–44 (2006).
Kok, J. F. An improved parameterization of wind-blown sand flux on mars that includes the effect of hysteresis. Geophys. Res. Lett. 37, L12202 (2010).
Lämmel, M., Dzikowski, K., Kroy, K., Oger, L. & Valance, A. Grain-scale modeling and splash parametrization for aeolian sand transport. Phys. Rev. E 95, 022902 (2017).
Andreotti, B., Claudin, P. & Douady, S. Selection of dune shapes and velocities part 2: A two-dimensional modelling. Eur. Phys. J. B 28, 341–352 (2002).
Kroy, K., Fischer, S. & Obermayer, B. The shape of barchan dunes. J. Phys. Condens. Matter 17, S1229–S1235 (2005).
Parteli, E. J. R., Durán, O. & Herrmann, H. J. Minimal size of a barchan dune. Phys. Rev. E 75, 011301 (2007).
Ho, T. D., Valance, A., Dupont, P. & Ould El Moctar, A. Scaling laws in aeolian sand transport. Phys. Rev. Lett. 106, 094501 (2011).
Jenkins, J. T. & Valance, A. Periodic trajectories in aeolian sand transport. Phys. Fluids 26, 073301 (2014).
Castaing, B., Gagne, Y. & Hopfinger, E. Velocity probability density functions of high Reynolds number turbulence. Phys. D 46, 177–200 (1990).
Bohr, T., Jensen, M. H., Paladin, G. & Vulpiani, A. Dynamical Systems Approach to Turbulence (Cambridge Univ. Press, Cambridge, 2005).
Sullivan, R. et al. Wind-driven particle mobility on mars: Insights from Mars Exploration Rover observations at “El Dorado” and surroundings at Gusev Crater. J. Geophys. Res. Planets 113, E06S07 (2008).
Acknowledgements
We thank E. Schmerler for his kind help with the sand sample preparation and analysis. This research was supported by a grant from the GIF, the German-Israeli Foundation for Scientific Research and Development (no. 1143-60.8/2011). We also acknowledge the hospitality of the KITP in Santa Barbara and the MPI-PKS in Dresden, where this work was started, and financial support by the National Science Foundation under grant no. NSF PHY-1125915, the MPI-PKS Visitors Program, and the German Academic Exchange Service (DAAD) through a Kurzstipendium (for M.L.).
Author information
Authors and Affiliations
Contributions
M.L. and K.K. developed the theory; M.L., A.M., H.Y., H.T. and I.K. designed and conducted the experiments and field surveys; M.L., A.M., I.K. and H.Y. analysed the data; M.L. and K.K. wrote the paper. All authors discussed the results and implications and commented on the manuscript at all stages.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary Figures 1–4, Supplementary Tables 1 and 2, Supplementary References 1–7
Rights and permissions
About this article
Cite this article
Lämmel, M., Meiwald, A., Yizhaq, H. et al. Aeolian sand sorting and megaripple formation. Nature Phys 14, 759–765 (2018). https://doi.org/10.1038/s41567-018-0106-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41567-018-0106-z
This article is cited by
-
Coevolving aerodynamic and impact ripples on Earth
Nature Geoscience (2024)
-
Megaripple mechanics: bimodal transport ingrained in bimodal sands
Nature Communications (2022)
-
Analyzing grain size distributions with the modal decomposition method: literature review and procedures
Bulletin of Engineering Geology and the Environment (2021)
-
Millennial paleotsunami history at Minna Island, southern Ryukyu Islands, Japan
Progress in Earth and Planetary Science (2020)
-
A unified model of ripples and dunes in water and planetary environments
Nature Geoscience (2019)