Grain separation. Experiment showing how different grains in a mixture separate into layers, an effect seen during the formation of sedimentary rocks

---

Grain separation. Experiment showing how different grains in a mixture separate into layers, an effect seen during the formation of sedimentary rocks such as sandstone. A mixture of sand & coloured sugar (red) is poured between 2 vertical sheets of glass. The mixture forms a mound whose sides periodically reach a critical angle, causing an avalanche. The smooth grains of sand stop short of the kink at the bottom of the heap, whilst the bigger, rougher sugar grains go a little further. As more grains fall the kink rides upward, forming 2 layers. Each succeeding avalanche makes another pair of layers. This experiment was devised by Hernan Makse of Boston University, USA, in 1997.

---

Size: 4488px × 4525px
Photo credit: © SAM OGDEN/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: effect, effects, experiment, experimnt, formation, geology, grain, layer, layering, layers, physical, physics, rock, sand, sandstone, sedimentary, separate, separation, strata, sugar