Fingers in a volcanic Dyke

Fingers of compacted grains on the side of a volcanic dyke. The dyke, a vertical thick sheet once full of magma, became more erodible than the surroundings after cooling. With time, the infill was eroded, and the side walls stitch out in the Neguev Desert. The sides of this dyke show particular features of labyrinthine lines protruding out of the rock. These lines, forming finger sides, branch and merge. They are made of the same hard grains as the surrounding sandstone, compactly packed together, while other minerals were expelled. See e.g. https://hal.archives-ouvertes.fr/hal-01685526v1 for a modelling of these dyke fingers, [video](https://www.youtube.com/watch?v=zQb_MhehRPY&feature=youtu.be). [ ITN FlowTrans](http://www.flowtrans.net) . Thanks to E Aharonov and G Baer, HUJI, for guiding us on there in 2013! J A Eriksen, R Toussaint, K J Måløy, E Flekkøy, O Galland, and B Sandnes (2018). Pattern formation of frictional fingers in a gravitational potential. Phys. Rev. Fluids 3, 013801