"tunnel valley"^^ . . "A deep but narrow valley with a 'U' shaped cross-section and frequently a 'U' shaped plan which is usually found filled with glacial till. It is formed when the edge of an ice mass advances up a slope. Its length may be appropriately measured in centimetres or kilometres, depending on the circumstances of formation."^^ . "tunnel-vale"^^ . "ENVO:00000436"^^ . . "Wikipedia:Tunnel_valley"^^ . "ENVO"^^ . "rinnental"^^ .