20/04/2017
Stone of the hats (El Calafate, Santa Cruz Province, Argentina. ) in the same province of Santa Cruz (Argentina) for the preview image, are these concretions quite striking. These "hats" are within a sedimentary rock and are large concretions formed by iron oxides. These oxides rushed around ferruginous kernels that facilitated this chemical precipitation, in a process geochemical favoured by circulating water by the interstices of the rock. Original Ferruginous kernels that facilitated the rainfall, they could have diverse origin. Without ruling out that could be several fragments of a "Siderolito" (meteorite composed of iron) who fell very close to each other (in other parts of the Patagonia Argentina have been found large siderolitos within marine limestone exploited for the production of cement. Concretions) these were way roughly spherical. What you see in this moment, forming the Central Corps of the hats, is the central part of the concrete around the nucleus, the more hardened and hence more resistant to erosion. What appears to be the "Wing" of the hats, it's the outside of each realization, less hardened and thus more easily removed by erosion with the whole of the rock. On the rock of the last photo of this series, you will see an "hat" almost entirely eliminated, and in their environment appear liesegang rings, which are typical halos of oxidation by activity interstitial geochemistry.