Related by context. Frequent words. (Click for all words.) 54 meteorite 53 underwater caves 51 dinosaur footprints 50 Lake Vostok 50 hydrothermal vent 49 geologically active 48 melting glacier 48 Namib Desert 48 meteor 48 volcanic crater 48 lunar soil 48 volcano erupting 47 crater 47 Chicxulub 47 dinosaur fossil 47 astronomical observatory 47 limestone cave 47 lava tubes 47 rock outcrop 47 volcanically active 47 geological formations 46 cave explorers 46 underground cavern 46 meteoroid 46 microfossils 46 fossilized remains 46 stalactite 46 Cabeus 46 Valles Marineris 45 Geologists 45 extrasolar planet 45 Oort Cloud 45 infrared telescope 45 lava tube 45 Martian rocks 45 peat bog 45 archeologists 45 dinosaur fossils 45 steam vents 45 active volcanoes 45 Tunguska 45 Meteorite 45 limestone caves 44 plesiosaur 44 Volcano erupts 44 paleontological 44 methane 44 stromatolites 44 Opportunity rover 44 volcanic vent 44 astrobiologists 44 marine sediments 44 dinosaur bones 44 spherules 44 Jupiter moons 44 Titan Saturn 44 aurorae 44 whale skeleton 44 beaver dam 44 Higgs particle 43 Saturn moon Enceladus 43 cavern 43 Sensing Satellite LCROSS 43 comet 43 methane hydrate 43 archaeological 43 Meridiani 43 Arctic permafrost 43 earth tremors 43 stalagmite 43 Archeologists 42 unexploded shells 42 magma chamber 42 alien spacecraft 42 meteorites 42 disused quarry 42 petroglyph 42 skull fragment 42 geologists 42 ancient pyramids 42 Saturn moon 42 methane hydrates 42 Martian equator 42 rock formations 42 archaeologists 42 Gliese #g 42 prehistoric 42 lakebed 42 Comet McNaught 42 moon Europa 42 particle detector 42 Endurance Crater 42 lake sediments 41 Martian landscape 41 igneous rock 41 termite mounds 41 Paleontologists 41 asteroid 41 Astrophysicists 41 archeological 41 limestone formations