- Sagan, Carl (1934-1996)
- Salt Wedging
- Saltation
- Saltwater
- Saltwater Encroachment
- Sand
- Sandstone
- Satellite
- Saturated Zone
- Schist
- Schrödinger, Erwin (1887-1961)
- Scientific Data Management in Earth Sciences
- Scientific Method
- Scilla, Agostino (1629-1700)
- Sea-Floor Spreading
- Seasonal Winds
- Seasons
- Seawalls and Beach Erosion
- Sedgwick, Reverend Adam (1785-1873)
- Sedimentary Rocks
- Sedimentation
- Seeing
- Seismograph
- Seismology
- SETI
- Shear Zones
- Shepard, Alan B. (1923-1998)
- Shock Metamorphism
- Silicic
- Silicon