How estuaries grow old Newsletter
- Author
- Terry Hume, Andrew Swales
- Year
- 2003
- Journal / Source
- Water & Atmosphere
- Publisher / Organisation
- NIWA
- Volume
- 11
- Number
- 1
- Summary
- Estuaries in New Zealand have not always looked like they do today. These semi-enclosed coastal water bodies, where land drainage mixes with the sea, began life about 6500 years ago, when climatic warming caused sea level to rise some 150 m to its present level. The sea level rise drowned an ancient and varied landscape. So, in the Auckland region, the seabed of present-day Hauraki Gulf was once a broad alluvial plain with meandering river channels incised into it and the coast was out beyond Great Barrier Island. In south-west New Zealand, the landscape was dominated by deep U-shaped valleys cut by glaciers. The “proto-estuaries” that formed as sea-level rose were very different from those we see today because since that time they have filled with sediment and grown old.