sao din na noi,soil textures eroded sandstone pillars, columns and cliffs, nan province,thailand

ancient arid asia cave chimney clay cliffssao columns cones conical conservation din dry eroded erosion formation geological geology ground hill history lalu land landscape limestone loss mount mountain nan nature noi old phrae pillar pillars provincethailandn rain red rock runoff sandstone scene sky soil stone terrain textures thai thailand tourism travel trekking trip valley view water weathering