Gossans, Slates, and the Red and Black Hamlets of Segovia (Spain): Interrelated Geological and Architectural Features

Abstract

The Sierra of Ayllón in Central Spain has a rich heritage from both the architectonic and geological perspectives. On one hand, the low lands flanking the northern side of the sierra in the Segovia Province host the so-called red hamlets and black hamlets (pueblos rojos-pueblos negros). The red and black terms derive from the traditional local building materials: Miocene red gossan breccias and Ordovician-Silurian black slates, respectively. Although these hamlets have a series of undeniable esthetic and historical values, it is the geology of this realm which accounts for most of the remarkable features in the studied zone. In this regard, near the hamlet of Madriguera, there are outstanding, unique outcrops of Miocene gossan deposits and deeply hydrothermally altered Silurian slates, forming what we have here defined as the “Madriguera Gossan Corridor” geosite. This, together with the intrinsic historical and esthetic values of the red and black hamlets, confers to the area (both at the regional and local scales) an immense scientific, educational, and touristic potential. The formal assessment of this site following the official methodology of the Geological Survey of Spain (IGME) confirms its highly valuable interest as a geosite.