3. Rudists in Ordesa




    There are in fact two specific spots on the path that leads from Pradera de Ordesa to Cola de Caballo. Pitted limestones can also be seen along a long stretch of the way. Geological unit C-M.



    Rudists are characteristic of some of the limestones in the gorges or the limestone formation of Estrecho. The fact that they easily dissolve and hence erode away leaves the limestone full of holes or pitted, a type of stone that is very common throughout the Ordesa-Monte Perdido Park.
    It is, therefore, difficult to find examples that have been preserved, in this case thanks to the ditches along the forest track. These are very delicate sites that must be protected.
    Rudists became extinct towards the close of the Cretaceous, as did the dinosaurs, but in the area with which we are concerned they are only plentiful in the limestone formation in the gorges.



    Two particular locations, one at UTM coordinates UTM 31T 251763 4727844 next to the top vantage points at Estrecho waterfall and another at UTM coordinates UTM 31T 252110 4725023 in Las Hayas wood. You can see pitted limestones, the holes in which are the result of the dissolution of rudist fossils in the area near both spots.