Ключевые слова: abstract, aged, background, cave, creation, crust, debris, dissolving, earth, effect, element, environment, eroded, erosion, excavation, exposed, formation, fossil, geological, geology, ground, historic, layers, mass, material, mine, mineral, mineralization, mountain, natural, process, rocks, science, search, sedimentary, sediments, site, slow, soil, stone, structure, surface, texture, textured, time, travel, vegetation,