Development of a chenier plain, Firth of Thames, New Zealand Journal Paper
- Author
- C.D. Woodroffe; R.J. Curtis; R.F. McLean
- Year
- 1983
- Journal / Source
- Marine Geology
- Publisher / Organisation
- Elsevier
- Volume
- 53
- Number
- 1-2
- Month
- August
- Pages
- 1-22
- Keywords
- chenier, Firth of Thames, Kaiaua, Miranda, Mactra ovata
- Summary
- A chenier plain is a prograded coastal plain in which ridges, composed of coarse material moved by longshore drift, are stranded overlying finer-grained marine or littoral sediments. Subsurface data from the Miranda coastal plain, Firth of Thames, New Zealand, confirm that shell ridges between Kaiaua and Miranda are true cheniers. Surveys of a modern chenier indicate that coarse sediment and shell form sand bars on the foreshore and that these migrate landwards through swash action. Subsequently a shell ridge is built on the sand bar from shell derived from offshore and reworked from the north, and storm events form a storm crest above high spring tide level. Deposition of fine-grained sediment occurs in an embayed tidal flat behind the chenier and within this environment the bivalve Mactra ovata is found. These sediments can accrete to an elevation at which mangrove and salt marsh are able to colonise.