borehole drifts downstream
1tunnels and underground excavations — ▪ engineering Introduction Great tunnels of the world Great tunnels of the worldhorizontal underground passageway produced by excavation or occasionally by nature s action in dissolving a soluble rock, such as limestone. A vertical opening …
2Dye 3 — is an ice core site and previously part of the Distant Early Warning (DEW) line, located at (65°11′N 43°49′W / 65.183°N 43.817°W / 65.183; 43.817 ( …
