Abyss, Alcove, Asylum, Bay, Breach, Break, Cache, Canyon, Carrel, Cavity, Chamfer, Chap, Chase, Chasm, Check, Chimney, Chink, Cleft, Col, Concealment, Corner, Couloir, Cove, Cover, Covert, Crack, Crevasse, Crevice, Cubicle, Cut, Dado, Defile, Dell, Den, Ditch, Donga, Draw, Dugout, Engraving, Excavation, Fault, Fissure, Flaw, Flute, Fluting, Foxhole, Fracture, Furrow, Gap, Gape, Gash, Gorge, Gouge, Groove, Gulf, Gully, Hideaway, Hideout, Hiding, Hole, Incision, Joint, Kloof, Lair, Leak, Moat, Niche, Nook, Notch, Opening, Pass, Passage, Ravine, Recess, Refuge, Rent, Retreat, Rifling, Rift, Rime, Ruck, Rupture, Rut, Sanctuary, Score, Scratch, Seam, Slit, Slot, Split, Streak, Striation, Trench, Valley, Void, Wadi, Wrinkle