Α - Β - Γ - Δ - Ε - Ζ - Η - Θ - Ι - Κ - Λ - Μ -
Ν - Ξ - Ο - Π - Ρ - Σ - Τ - Υ - Φ - Χ - Ψ - Ω
A - B - C - D - E - F - G - H - I - J - K - L - M -
N - O - P - Q - R - S - T - U - V - W - X - Y - Z
0 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9
Oasis
Observation well
Ocean-basin crustal type
Ocean-basin floor
Oceanic crust
Oceanicity
Oceanic plateau
Oceanic-trench crustal type
Ocean-island basalt
Ocean wave
Ochoan
Odderade
Oddo–Harkins rule
Odintsovo
ODP, Ocean Drilling Programme
Oedometer
Oersted
Offshore zone
Ogive
Oikocryst
Oldham, Richard Dixon
Old Red Sandstone Continent
Olduvai
Olenekian
Oligomictic
Oligotaxic times
Olivine
Omphacite
Onesquethawian
One-way travel time
Onnian
Onondagan
Ontarian
Opal
Ophiolite
Opoitian
Oppel, Albert
Oppel zone
Oxfordian (stage)
