garganta de los infiernos natural reserve, extremadura, spain

pilones huge granite roundshaoed forms carved square format fluvial erosion garganta infiernos reserve extremadura spain bed affluent jerte river cavities marmits tectonic reactivation running water natural pools cold turquoise crystalline upper trekkers early autumn season travel sierra tormantos gredos valley space hells gorge southwestern side tornacavas cabezuela del valle mountains gneiss hydrographic network giant potholes sun flares