A canyon or gorge is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Long cut into volcanic rock layer layers tendency sediments erosion washout denudation slot canyons narrow land landslide landslip slide slip slumping geology topography karst valley large brown mainland continent bedrock stony rocky stone escarpment steep slope cliff separates elevation scarp cuesta hill ridge sedimentary horizontal scarpland dip topographic geomorphic cracked broken scree rockfall talus deposits floor Chuluut Khangai Ider Mongolia Mongolian Central Asia aerial fly flying drone overhead over above water creek brook stream UHD 4K 3840X2160