Related by context. Frequent words. (Click for all words.) 61 volcanism 61 marine sediments 61 Younger Dryas 59 interglacial period 59 ejecta 59 glaciation 59 continental crust 58 oceanic crust 57 mass extinction 57 Precambrian 56 sedimentary rock 56 supernova explosion 55 olivine 55 meteoroid 55 Paleocene 55 Quaternary 55 lavas 54 isotopic 54 mass extinctions 54 Ordovician 54 tetrapods 54 megafauna 54 scarps 54 zircons 54 Pliocene 54 lithosphere 54 magma chamber 54 interglacial 53 microfossils 53 supernova remnant 53 Gliese #g 53 oxygen isotopes 53 Late Cretaceous 53 crustal 53 radiocarbon 53 basalts 53 diatoms 53 geologically active 52 greenhouse warming 52 tyrannosaur 52 calcite 52 magnetar 52 polar caps 52 Archaeopteryx 52 radiocarbon dating 52 continental drift 52 subatomic particle 52 subduction zones 52 radioactive decay 52 geologic 52 Medieval Warm Period 52 glacial melting 52 Little Ice Age 52 Saturn rings 52 mid latitudes 51 atmospheric CO 51 Iapetus 51 cosmic microwave background 51 Tunguska 51 microlensing 51 Australopithecus 51 thermosphere 51 GRBs 51 quark gluon plasma 51 plate tectonics 51 landforms 51 Carboniferous 51 gamma ray burst 51 lake sediments 51 silicates 51 sediments 51 Cretaceous Period 51 magmatic 50 Eocene 50 Meridiani 50 diatom 50 Tiktaalik 50 gravitational lensing 50 pterosaur 50 sunspot cycle 50 ocean ridges 50 seamount 50 cometary 50 Kuiper belt 50 earth crust 50 retreating glaciers 50 sunspot activity 50 cosmologists 50 glacial melt 50 lava flows 50 theropods 50 extrasolar planets 50 atmospheric carbon dioxide 50 hadrosaur 50 terrestrial ecosystems 50 landmasses 50 volcanically active 50 basalt 49 hydrothermal 49 hydrothermal vents 49 methane hydrates