Near Liberia, capital of the Guanacaste Province.
From Liberia to Rincón de la Vieja National Park winds a road of unusual, resplendent white rocks. The rocks that make up this formation are known as ignimbrite and alternate with basalt and andesite lava-flows. They are of volcanic origin and have a low density and are unable to retain moisture well. This explains why some areas of the Guanacaste region, which lie less than 500 meters above sea level and are covered with ignimbrite rocks, feature a predominant groth of small oak groves, a species adapted to this kind of lithology and the dry climatic conditions. This is the case of the plains and foothills north of the city of Liberia and the Santa Rosa plateau.
Where the inimbrite terrain has been carved by rivers, there are deep, wide canyons or "Talwege", a German term that means valley road and is used to describe the longitudinal profile of a river. A typical example can be seen at the massive River Liberia Canyons with walls of 90°. A lush gallery forest grows at the base of the canyon walls. The most spectacular is located 12 km northeast of Liberia, on the road to Colonia Blanca and Rincón de la Vieja National Park.