Pitted pebbles

As early as 1863 Sorby proved that pitted pebbles are the result of solution at the points of mutual contact in a conglomerate. As cause he suggested solution under pressure in saturated, stagnant groundwater by what has afterwards been designated Riecke’s principle. By the examination of polished cuts through a pitted conglomerate I found confirmation of this hypothesis. The alternate explanation by Daubrée, Kumm and others of solution in water held by capillarity at the points of contact could not cause the observed shapes of the pits. The experiments they used to disprove Sorby’s view are fundamentally incorrect. They attempted to form pits by a solvent liquid, instead of using pressure and saturated water. Groningen, November 1942.