The end of the Permian period is characterized by the largest mass extinction ever recorded in marine and terrestrial sedimentary rocks. The oldest plant macro-remains after the P–T boundary recorded in the Castilian Branch of the Iberian Range after this mass extinction belong to the Eslida Formation of Anisian age. These associations have been recovered at four localities and include sphenophytes (Equisetites, perhaps Neocalamites or Schizoneura), conifers (Volzia, Albertia, Pelourdea), lycophytes (Pleuromeia) and a possible seed fern (Peltaspermum).
Facies associations and sedimentological analysis of the Eslida Formation have allowed for distinguishing four architectural elements: CH (channel deposits), LA (lateral accretion), CS (crevasse splay) and FF (overbank fines). The largest fossil remains are associated with CH and LA architectural elements and high-energy events, and they form part of the basal lag or reactivation surfaces. Smaller and well-preserved fragments are associated with the CS architectural elements.
A sedimentologic, taphonomic and palaeoclimatic analysis reveals gradation from riparian hygrophytic vegetation to semi-arid xerophitic vegetation across the alluvial complexes and a progressive aridification through time. A comparison with other areas shows that this association is similar to coeval floras of Iberia and of the “Grès à Voltzia” Formation of northeastern France.