Related by context. Frequent words. (Click for all words.) 65 lava tubes 64 basalt 60 volcanic rock 59 sandstone formations 58 granite cliffs 58 basaltic 57 limestone 56 rock outcrops 56 escarpments 56 limestone formations 56 granite boulders 55 magma chamber 55 sandstone 55 stalactite 54 Valles Marineris 54 landform 54 lava tube 54 salt crystals 54 sedimentary rock 54 volcanic crater 54 aragonite 54 calcareous 53 rock outcrop 53 mudstone 53 igneous rock 53 clasts 53 sand dredged 53 sediment 52 hydrothermal vent 52 deep gorges 52 silts 52 volcanic peaks 52 pumice 52 oceanic crust 52 landforms 52 limestone cave 52 steam vents 52 rock formations 52 silt 52 inter tidal 52 igneous rocks 52 rocky outcrops 52 undersea volcanoes 52 marine sediments 52 calcite 52 Meteor Crater 52 karst 52 lakebed 51 lunar soil 51 petrified wood 51 intertidal 51 lavas 51 lava rocks 51 glacial till 51 petroglyph 51 middens 51 Spiral Jetty 51 evergreen forests 51 Sediments 51 mudstones 51 outcroppings 51 ridges 51 embayment 51 mud volcanoes 51 biogeochemical 51 snail shells 51 alluvium 51 alternating layers 51 temperate rainforest 51 continental crust 51 trackway 51 extinct volcano 50 pyroclastic 50 caldera 50 quartzite 50 temperature gradient 50 basalts 50 stalagmite 50 palisades 50 ammonites 50 volcanic 50 calcrete 50 rocks 50 Namib Desert 50 limestone caves 50 lava 50 sediments 50 granite 50 crustal 49 lush rainforest 49 metamorphic rocks 49 limestones 49 stromatolites 49 moss covered 49 geological formations 49 mudflat 49 montane 49 peridotite 49 calcium carbonate 49 syncline 49 siliceous