natural barriers
Terrain blocking passage
Natural barriers are geographical features that impede movement or separate territories—mountains, rivers, deserts, oceans.
They historically determined borders, slowed invasions, and isolated populations: The Pyrenees form a natural barrier between France and Spain.
The term extends to anything inherent that blocks progress: Shyness can be a natural barrier to making friends.
- oceansVast saltwater bodies
- desertsAbandons or barren lands
- cliffsSteep natural rock walls
- glaciersSlow-moving ice masses
- forestsDensely treed land areas
dense jungle · mountains · fjords · straits · plateaus · islands · canyons · terrain · coral reefs · fog · chokepoints · no man's land · mangroves · steep cliffs · ice sheets · polar ice · rivers · coastlines
- bordersborder, boundary, border crossing, national borders, boundary line
- mountain boundariesridges, ridge lines, watersheds, peaks, summits
natural barrierswalls
Vertical enclosing structures
fences · fortifications · barricades · dams · levees
natural barriersmountain passes
Routes traversing elevated ranges
land bridges · open plains · river valleys · river crossings · trade routes