Earth science
Articles about geology, climate, oceans and the planet.
Neogene
Neoproterozoic
Nevado del Ruiz
Nevado del Ruiz — snow‑capped volcano in Colombia and the Armero disaster
Nevado Tres Cruces
New Red Sandstone
Nintoku Seamount
Nitrogen narcosis
Nor'easter
North American plate
Nubian Sandstone Aquifer System
Nuclear winter
Nuclear winter: causes, effects, history, and uncertainties
Numerical weather prediction
Nuvvuagittuq Greenstone Belt
Nyamuragira
Nyamuragira: Shield Volcano and One of Africa's Most Active Volcanoes
Oblate spheroid
Obsidian
Occluded front
Ocean
Ocean acidification
Ocean current
Ocean gyre
Ocean surface wave
Oceanic climate
Oceanic climate (maritime climate)
Oceanic crust
Oceanic trench
Oceanography
Oceanography: The Science of the Seas and Marine Environment
Oil field
Oil sands
Oil sands (tar sands): composition, extraction, impacts, and global significance
Ōjin Seamount
Ōjin Seamount: Extinct Guyot in the Hawaiian–Emperor Seamount Chain
Ojos del Salado
Ojos del Salado: Highest Active Volcano and Second-Highest Peak in the Americas
Ol Doinyo Lengai
Ol Doinyo Lengai: Tanzania’s unique carbonatite volcano
Old Earth creationism
Old Faithful Geyser
Old Red Sandstone
Oldest dated rocks
Oldest dated rocks and minerals on Earth and the Moon
Oligocene
Oligocene epoch
Olivine
Onyx
Onyx: banded chalcedony used as gemstone and ornamental stone
Ooid
Ooid: small concentrically layered carbonate grain
Opal
Ophiolite
Ophiolite: exposed sections of oceanic crust and upper mantle
Orbital forcing
Orbiting Carbon Observatory
Orbiting Carbon Observatory (OCO)
Ore
Orogeny
Orosirian
Orosirian Period (Palaeoproterozoic): 2.05–1.80 billion years ago