Limestone Portal
The limestone cliffs that shape the Ruta del Cares cup their palms to reveal an arch, Picos de Europa National Park, Asturias, España. Limestone is often highly eroded because the moderate acidity of rainwater slowly dissolves the carbonate that forms the basis of the rock. Limestone layers are thus often riddled with caverns and sinkholes, such as the great cenotes in the Yucatán peninsula of México. This is the only example of a limestone arch that I can recall encountering.
Limestone Portal
The limestone cliffs that shape the Ruta del Cares cup their palms to reveal an arch, Picos de Europa National Park, Asturias, España. Limestone is often highly eroded because the moderate acidity of rainwater slowly dissolves the carbonate that forms the basis of the rock. Limestone layers are thus often riddled with caverns and sinkholes, such as the great cenotes in the Yucatán peninsula of México. This is the only example of a limestone arch that I can recall encountering.