Geology and Geomorphology
The Kaikoura Peninsula is located on the east coast of the South Island of New Zealand. Geologically the peninsula consists of an asymmetrical anticline bounded on either side by two synclines, the axis of which strikes northeast–southwest. The peninsula is made up of two different types of sedimentary rocks, the Amuri Limestone of Palaeocene age and Oligocene aged mudstone. Intense folding and minor faulting have occurred, particularly in the limestone area. Shore platforms are developed in both lithological units, those in limestone displaying wider variability in morphology. The multi-level terraces were once wave-cut platforms, created at sea level and uplifted out of the sea by tectonic processes, at which point the next step would be cut. In the landscape they appear as a flight of terraces with the oldest appearing at the top and the youngest at the shoreline where the Kaikoura township is situated.
The shoreline of the Kaikoura Peninsula is exposed to an extremely long fetch from the Pacific Ocean, and it is also characterized as a high-energy oceanic swell environment, with high-energy storms interrupting long periods of relative calm. High-energy storms due to the passage of cyclonic depressions over New Zealand can occur at any time of the year. The Kaikoura Coast is mesotidal with a mean range of 1.36 m and a maximum of 2.57 m. The region has a temperate climate with moderate rainfall, averaging 865 mm per year and mean monthly temperatures range from 7.7° Celsius in July to 16.2° Celsius in January.
The Kaikoura Peninsula environment is subject to highly energetic processes in terms of both marine and weathering processes. Shore platforms are exposed to the dominant wave directions and are in the intertidal zone. Consequently, both marine erosive forces and subaerial weathering processes contribute to erosion. Shore platforms range from 40 m to over 200 m wide and are cut in Tertiary mudstones and limestones.
Tectonic uplift of the peninsula is estimated to be in the order of 100 metres during the Quaternary and 2 metres during the last 1000 years. The shore platforms are therefore clearly polycyclic and contain inherent morphological features but are being actively rejuvenated by the removal of cover deposits.
Four main phases of tectonic activity are identified for the last 5–6000 years. These involve changing tectonic-eustatic levels, platform processes and erosional episodes in the hinterland. Consequently the platforms are rapidly evolving features which reflect both contemporary processes and recent tectonic history.
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