The Natural Park of Aiako Harria, Jaizkibel and Oarsoaldea are exposed in the geological map prepared by the Department of Geology of the Society of Aranzadi Sciences and the Luberri Geological Unit of Oiartzun. It is a colorful three-dimensional map that shows the rich geological and paleontological heritage of the area. It gathers the oldest rocks of Gipuzkoa and some of the oldest that emerged in the Basque geography, allowing to back 400 million years in geological history.