Lower Silurian (Llandovery) sedimentary rocks crop out in the western part of the Cordon de Lila mountain range These are the first fossiliferous Silurian rocks discovered in Chile and were named Quebrada Ancha Formation A stratigraphic section of c 200 m thick was levelled, which is formed by conglomerates sandstones and sandy limestones, which were divided Into three units Units 1 and 3 correspond to a high energy near shore environment Unit 2 contains abundant brachiopods and conularids The brachiopods represent a very shallow subtidal Benthic Assemblage dominated by Hindella, which represents 79 per cent of the brachiopods collection The extensive collecting of the abundant brachiopod fauna allowed the study of the variability of the meristelloid brachiopod Hindella crassa incipiens.