The Hoces del Río Riaza Natural Park, Spain: A possible new member of the European Geoparks Network, Global Geoparks Network, UNESCO

A short time after the main guidelines of the "Geopark" concept were proposed (June, 2000), the European Geoparks Network (EGN) was established. This organization aimed to protect geodiversity, is integrated in the Global Geoparks Network, UNESCO, and defined a "European Geopark" as a territory, which include a particular geological heritage and a sustainable territorial development strategy, supported by an European program to promote development. EGN must comprise a certain number of geological sites of particular importance in terms of their scientific quality, rarity, aesthetic appeal or educational value. At present, the EGN is composed by 32 Geoparks across 13 European countries. According to the spirit of the Geoparks, it should be very appropriate to establish within each European country a number of Geoparks representative of its geological heritage.

The “Hoces del Río Riaza Natural Park” is located in Spain, at the southern border of the Tertiary Duero Basin. The Riaza River, tributary of the Duero River, crosses lengthwise the Park with deep gorges on its margins. The geology of the park comprises continental (terrigenous) and marine (carbonate) Cretaceous sediments, uncomformably overlaud by continental Neogene-Quaternary deposits. The Alpine Orogeny folded the Cretaceous, and controlled the sedimentation of the Neogene-Quaternary sediments, which are composed of several, stacked alluvial fans grading laterally into fluvio-lacustrine sediments. The compressional stresses of this orogeny also originated faults and joints. This park also shows a good representation of Mesozoic and Cenozoic fauna, such as pelecypods, rudists, gastropods, cephalopods, stromatolites, ostracods and forminifers.

Thus, the Hoces del Río Riaza Natural Park can be considered an excellent example of geological heritage, being a possible new member of the EGN, Global Geoparks Network, UNESCO.