- O Pré-sal brasileiro e suas vertentes
- Ocean Energy and Coastal Protection
- Ocean Governance
- Offshore Exploration of Oil and Gas in Cuba using Digital Elevation Models (DEMs)
- Oil and Gas Exploration
- Oil and Gas Exploration in Cuba
- Oil Panic and the Global Crisis
- Oil Shales
- Old Red Sandstone: New Walks in an Old Field
- On Significant Applications of Geophysical Methods
- On the Law Which Has Regulated the Introduction of New Species
- On The Origin of Species
- One Hundred Proofs that the Earth is Not a Globe
- Onshore-Offshore Relationships on the North Atlantic Margin
- Opening and Closure of the Neuquén Basin in the Southern Andes
- Ordovician Trilobites
- Ore Deposits
- Origin and Evolution of Earth
- Origin and Evolution of the Cape Mountains and Karoo Basin
- Origin and Formation of Coastal Boulder Deposits at Galway Bay and the Aran Islands, Western Ireland
- Origin and History of the Earth
- Origin of Carbonate Sedimentary Rocks
- Origins
- Orogenic-Type Polymetallic Mineralization Associated with Multistage Orogenesis in Northern North Ch...
- Orígenes
- Ostracoda as Proxies for Quaternary Climate Change (Enhanced Edition)
- Our Beautiful Moon and its Mysterious Magnetism