Related by context. Frequent words. (Click for all words.) 65 igneous rocks 62 iron oxides 62 marine sediments 60 sedimentary rock 60 lavas 60 salt crystals 60 lava tubes 60 igneous rock 59 basalt 59 calcareous 59 volcanic rock 59 olivine 59 lunar soil 58 isotopic composition 58 clasts 58 silicates 58 calcite 58 striations 57 basaltic 57 silicate 57 continental crust 57 stalactite 57 hydrothermal activity 57 mud volcanoes 57 spherules 56 peridotite 56 coarse sand 56 microfossils 56 landforms 56 magmas 56 basalts 56 oceanic crust 56 calcium carbonate 56 glacial till 56 sediments 56 calcium sulfate 56 soils 55 alternating layers 55 lichen 55 zircons 55 lake sediments 54 pumice 54 resinous 54 greenish brown 54 carbonaceous 54 lithosphere 54 regolith 54 haematite 54 limestone 54 apatite 54 Meridiani 54 reddish color 54 moss 54 elemental composition 54 silts 54 alluvium 53 zeolites 53 icy crust 53 Sediments 53 Lake Vostok 53 stromatolites 53 sulphates 53 sphagnum moss 53 igneous 53 dacite 53 lotus leaf 53 oxygen isotopes 53 siliceous 53 chemical composition 53 silica 53 feldspar 53 mudstone 53 geologic formation 53 sulphate 53 methane hydrate 53 bathymetry 53 aerosol particles 53 rock outcrops 52 oxidization 52 limestones 52 polar vortex 52 moraines 52 Arctic permafrost 52 kerogen 52 carbonic acid 52 petrified wood 52 hydrological cycle 52 martian soil 52 depositional 52 calcrete 52 biogeochemical 52 nacre 52 limestone formations 52 mineral salts 52 volcanism 52 patinas 52 muds 52 steam vents 52 landform 52 lichens 52 exfoliated