La Rioja is a small autonomous community and province in the north of the Iberian Peninsula. The rivers Ebro and Oja drain the mountainous province, which is located in the Iberian System, with altitudes ranging between 1,000m and 2,000m asl. The highest peak is the Monte San Lorenzo (2,271m asl). The seven valleys are rather famous, a series of seven parallel valleys draining rapidly towards the Ebro from the mountain range. The mountain ridges typically form steep plateaus to the east and escarpments to the west, in other words the sedimentary layers dip towards the east with and angle greater than 40°. Such structures are called hogback in geology. They are named, from east to west, Alhama, Cidacos, Leza, Iregua, Najerilla, Oja and Tirón.
La Rioja has numerous karstified areas and also numerous caves, nevertheless it is quite small and has only one show cave, which is rather young. Currently we have no knowledge about any other underground site.