offset vertical seismic profiling - ore-hosting calcareous siltstones
- opesiula
- opesium
- ophicalcite
- ophicephalous
- ophimottling
- Ophiocistioidea
- ophiolite
- ophiolitic
- ophiolitic series
- ophirhabd
- ophite
- ophitic
- ophitic texture
- ophthalmite
- Opisthobranchia
- opisthoclade
- opisthocline
- opisthodetic
- opisthognathous
- opisthogyrate
- opisthosoma
- Oppelzone
- opposing wind
- opposite geomagnetic polarity
- opposite time-distance curves
- opposite time-distance graphs
- opposite traveltime curves
- opposite traveltime graphs
- opposite-leaved
- opposition
- opthalmite
- optic angle
- optic axial angle
- optic axial plane
- optic orientation
- optic sign
- optical
- optical activity
- optical altimeter
- optical character