Subject
- Railroads1
- Recreation areas1
- Reefs1
- Refuse and refuse disposal1
- Reservoirs1
- Roads1
- Sand1
- Sewage disposal plants1
- Soil and civilization1
- Sports facilities1
- Storage tanks1
- Swamps1
- Trails1
- Trees1
- Vegetation and climate1
- Vegetation classification1
- Vegetation mapping1
- Waste disposal sites1
- Water treatment plants1
- Windmills1