| Answer | Crossword Clue |
|---|---|
| hypogene | formed underground |
| SINKHOLE | Topographical feature formed by underground erosion |
| subaerial | Existing, occurring, or formed in the open air or on the earth's surface, not underwater or underground |
| potholes | A deep natural underground cavity formed by the erosion of rock, esp. by the action of water |
| anthill | mound of earth, leaves, etc., formed by a colony of ants in digging or constructing their underground nest |
| resistances | The underground movement formed in France during World War II to fight the German occupying forces and the Vichy government |
