ABSTRACT The Porvenir serpentinites are an ~600-m-thick body of meta-peridotites exposed in SW Iberia (Variscan Orogen). The serpentinites occur as a horse within a Carboniferous, out-of-sequence thrust system (Espiel thrust). This thrust juxtaposes the serpentinites and peri-Gondwanan strata onto younger peri-Gondwanan strata, with the serpentinites occupying an intermediate position. Reconstruction of the pre-Espiel thrust structure results in a vertical juxtaposition of terranes: Cambrian strata below, Porvenir serpentinites in the middle, and the strata at the footwall to the Espiel thrust culminating the tectonic pile. The reconstructed tectonic pile accounts for yet another major thrusting event, since a section of upper mantle (Porvenir serpentinites) was sandwiched between two tectonic slices of continental crust (a suture zone sensu lato). The primary lower plate to the suture is now overlying the upper plate due to the Espiel thrust. Lochkovian strata in the upper plate and the Devonian, NE-verging folds in the lower plate suggest SW-directed accretion of the lower plate during the Devonian, i.e., Laurussia-directed underthrusting for the closure of a Devonian intra-Gondwana basin. Obduction of the Porvenir serpentinites was a two-step process: one connected to the development of a Devonian suture zone, and another related to out-of-sequence thrusting that cut the suture zone and brought upward a tectonic slice of upper mantle rocks hosted in that suture. The primary Laurussia-dipping geometry inferred for this partially obducted suture zone fits the geometry, kinematics, and timing of the Late Devonian suture zone exposed in NW Iberia and may represent the continuation of such suture into SW Iberia.

Abstract Cadalso de los Vidrios leucogranite is extracted from the Sierra de Guadarrama (Spanish Central System) under the trade name ‘Blanco Cristal’. It is a fine- to medium-grained, hypidiomorphic and equigranular building stone that has been used in many heritage buildings, such as the Villena Palace (1534). The current annual production of Cadalso de los Vidrios leucogranite is approximately 8000 m 3 , of which 40% is exported around the world. It has been used in places such as the Vieux-Port in Marseille (France), Cork International Airport (Ireland) and the Puri EXIM Bank of Jakarta (Indonesia) among others. It is currently being used in the construction of the iconic tower of Jesus Christ of the Sagrada Familia Basilica, in Barcelona (Spain). Cadalso de los Vidrios leucogranite Blanco Cristal has excellent petrophysical properties, a uniform colour and good resistance to thermal shock and freezing temperatures. These qualities make Blanco Cristal an ideal material for monuments and buildings.

Abstract The knowledge that societies have of their geological environment and of the materials used in their heritage is of great importance for the sustainable use and conservation of traditional natural stone architecture. Similar weathering mechanisms occur in natural environments and the built environment and, in both cases, weathering may endanger both natural and built heritage. The Sierra de Guadarrama (Spanish Central System) is a privileged area in which natural and built heritage coexist. This paper describes an area of particular monumental and geological interest on the northern slopes of the Sierra de Guadarrama; its main aim is to propose an itinerary for members of the public, presented as a route through the area around Segovia, in which architecture/cultural heritage and an Earth sciences approach are brought together with an educational purpose. To this end, some connections are established between weathering forms in natural and built environments, as well as between the lithological characteristics of the rocks used in construction of ancient monuments in the area and the distribution of stresses and loads of walls.