Related by context. Frequent words. (Click for all words.) 69 interglacial 65 glaciation 62 PETM 61 volcanism 60 Little Ice Age 59 Cretaceous Period 59 Late Cretaceous 59 Medieval Warm Period 58 mass extinction 57 mass extinctions 56 supernova explosion 56 Pliocene 56 Pleistocene 56 Holocene 55 megafauna 55 marine sediments 54 Quaternary 54 greenhouse warming 54 sunspot cycle 54 hydrological cycle 53 magnetar 53 Precambrian 53 Ordovician 52 atmospheric carbon dioxide 52 lithosphere 52 sunspot activity 52 terrestrial ecosystems 52 multicellular organisms 52 plate tectonics 52 continental drift 52 atmospheric CO2 51 anatomically modern 51 anoxic 51 Ice Age 51 X ray emission 51 Eocene 51 multicellular 51 CO2 concentrations 51 sunspot 50 isotopic 50 mid latitudes 50 atmospheric circulation 50 Carboniferous 50 diatoms 49 Cretaceous 49 eruptive 49 volcanic eruptions 49 methane hydrates 49 Mesozoic 49 lake sediments 49 gamma ray burst 49 supernova explosions 49 sunspots 49 Bose Einstein condensate 49 El Ninos 49 Archaea 49 ENSO 49 crustal 49 Homo sapiens 49 diatom 49 fossil 49 subtropical regions 49 cosmic microwave background 48 glacial melt 48 equatorial regions 48 dinosaurs roamed 48 stalagmite 48 species extinctions 48 volcanic activity 48 genus Homo 48 Australopithecus 48 eukaryotes 48 Archaeopteryx 48 auroral 48 archaea 48 magmatic 48 extinctions 48 speciation 48 single celled organisms 48 single celled 48 El Niño 48 coral bleaching 48 geologically active 48 oxygen isotopes 48 sedimentary rock 48 upwelling 48 trilobites 47 volcanic 47 anthropogenic 47 mammoths 47 methane hydrate 47 Gliese #g 47 Tibetan Plateau 47 radioactive decay 47 geomagnetic storm 47 equatorial 47 abiotic 47 Earth crust 47 Crab Nebula 47 decadal 47 mountain glaciers