garganta de los infiernos natural reserve, extremadura, spain

riverbed running water natural pools cold turquoise crystalline waters hydrographic network rocks upper long format whirlpool eddy pilones rapids background garganta infiernos reserve extremadura spain affluent jerte river cavities marmits huge granite roundshaoed forms carved fluvial erosion tectonic reactivation early autumn season travel sierra tormantos gredos valley hells gorge southwestern side tornacavas cabezuela del valle mountains gneiss giant potholes