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Abstract
Dunes of the Pegasus Bay progradation sequence, North Canterbury, New Zealand, have been assigned previously to three soil‐based systems, with age estimates based on inferred rates of coastal progradation and soil development. The present study of the coastal reach between the Kowai and Ashley Rivers, Pegasus Bay, identifies five transverse dune systems. The dune ridge systems trend subparallel to the coast and each system relates to a specific, relict or active, sand and/or mixed sand and gravel beach. A morphogenetic classification based on the relationship of the dunes to the prior strandlines is proposed. This is supported by an absolute (coarse fraction thermoluminescence) chronology of the dune systems. Dune‐forming events occurred at c. 6500, <6000, <2600, 1000, and 500 years ago.
The transverse dune ridges relate to onshore northeasterly winds. The effective inland penetration of these winds with respect to sand transport is limited to a few hundred metres. Transverse dunes inland of the modern coast are being slowly degraded by the development of low‐amplitude parabolic dunes aligned with the northwest fohn wind. These winds are blowing sand back towards the beach.
