Beach and nearshore morphology and sedimentation in Fiordland, New Zealand: a comparison between fiords and glacial lakes

Abstract

The morphology of 56 beaches from the Fiordland coast is described. Four groups of beaches are recognised: open coast sand beaches, fiord margin sand/gravel beaches, fiord margin boulder beaches, and bay head deltas. Fiord margin beaches and deltas have a shelf profile; on the fiord margin beaches this shelf is narrow and steep and is formed by local wind waves, and on the bay head deltas the shelf is wide and flat and the morphology is controlled by the rate of sediment supply. The ocean fiord beaches have a deep-water shelf.

On sheltered beaches sediments fine across the shelf, with a transition from sand to mud at the shelf break. The sediment distribution and morphology of the inner fiord beaches is similar to that on nearby glacial lakes and is a model of progradational shelf formation on the continental margins.

Keywords:

• beaches
• nearshore environment
• fiords
• glacial lakes
• sediments
• Fiordland
• shore features
• limnology