Related by context. Frequent words. (Click for all words.) 63 geological formations 61 sedimentary rock 61 sandstone 57 stalactites 56 geologically 55 landforms 55 volcanic rock 55 stalagmites 55 basalt 54 cliffs 54 canyon walls 53 outcroppings 53 lava 53 lava flows 53 shale formations 53 limestone 53 waterfalls 53 geologic 52 sandstones 51 caverns 51 sedimentary rocks 50 petroglyphs 50 shales 50 ridges 49 caves 49 karst 49 geological 49 boulders 49 caldera 48 mountain ranges 48 gullies 48 coal seams 48 steep cliffs 48 quartzite 48 cavern 48 hot springs 48 crags 48 sediments 47 magma 47 molten rock 47 volcanic 47 rocks 47 volcanoes 46 mountain peaks 46 topography 46 sands 46 sand dunes 46 canyon 46 volcanic rocks 46 geysers 46 outcrops 46 Earth crust 45 shale 45 calcite 45 geology 45 sandbars 45 boulder 45 hydrothermal 45 waterfall 45 dunes 44 escarpment 44 dolomite 44 canyons 44 outcropping 44 vistas 44 glacier 44 glaciers 44 sedimentary 44 volcanism 44 earth crust 44 shale deposits 44 hydrothermal vents 43 nebulae 43 aquifers 43 volcanic activity 43 steep slopes 43 fossils 43 pictographs 43 formations 43 basins 43 cave 42 ocher 42 reservoir 42 ridge 42 lava flow 42 travertine 42 sediment 42 outcrop 42 gorges 42 gas hydrates 42 nebula 42 schist 41 granites 41 dinosaur bones 41 molten lava 41 landscapes 41 opal 41 lichen 41 jagged rocks 41 subsurface 41 crevasses