Relaxing river sound - Gentle river, Nature sounds, Singing birds ambience

A sound is often formed by the seas flooding a river valley. This produces a long inlet where the sloping valley hillsides descend to sea-level and continue beneath the water to form a sloping sea floor. The Marlborough Sounds in New Zealand are good examples of this type of formation. Sometimes a sound is produced by a glacier carving out a valley on a coast then receding, or the sea invading a glacier valley. The glacier produces a sound that often has steep, near vertical sides that extend deep under water. The sea floor is often flat and deeper at the landward end than the seaward end, due to glacial moraine deposits. This type of sound is more properly termed a fjord (or fiord). The sounds in Fiordland, New Zealand, have been formed this way. A sound generally connotes a protected anchorage. It can be part of most large islands. In the more general northern European usage, a sound is a strait or the narrowest part of a strait. In Scandinavia and around the Baltic Sea, there are more than a hundred s