Observations of the incipient and penultimate stages of Holocene marine terrace development

Dickson, M. E. et al. (2022) Observations of the incipient and penultimate stages of Holocene marine terrace development. Earth Surface Processes and Landforms, 47(13), pp. 3019-3032. (doi: 10.1002/esp.5440)

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Abstract

Flights of Holocene marine terraces are useful for reconstructing past earthquakes, but coastal erosion can remove terraces from the landscape, potentially leading to incorrect estimates of earthquake magnitude and frequency. Relatively little effort has been afforded to studying terrace erosion processes, and this paper presents the first field evidence that we are aware of documenting terrace erosion rates. Two case studies from New Zealand provide a unique opportunity to observe the beginning and end phases of terrace development. We present downwear and backwear erosion measurements, showing that both sets of processes are important. Micro-erosion meter measurements from Kaikōura Peninsula, South Island, confirm that downwear processes are modifying new marine terraces that were created when the peninsula was uplifted about 1 m during the 2016 earthquake. Erosion rates were high immediately following uplift as the relatively barren intertidal rock shore platform rapidly transformed into an incipient marine terrace with cover deposits. However, the Kaikōura earthquake uplifted shore platforms only a small distance above the upper tidal limit and ongoing downwear and backwear erosion may begin to remove parts of this terrace in future decades. We explored this prospect with a case study at Māhia Peninsula, North Island, where 100–300 years have elapsed since the last terrace-forming earthquake. Historical photographs were used to document about 80 years of backwear erosion. Terrace erosion rates have been nearly constant through this period, and extrapolation implies that the terrace will be removed in places by 2030. The erosion data in this paper provide new insights into how terraces can be removed from the landscape, but there are many complicating factors. To help understand these factors we present a new conceptual model of marine terrace creation and destruction for soft-rock coasts.

Item Type:Articles
Additional Information:Funding support was provided by the Royal Society Te Apārangi, Marsden Fund Grant Number UOO1828, University of Otago Research Grants 2017 2018, University of Otago Division of Humanities Research Grant 2017, University of Otago School of Geography Strategic Fund 2017.
Keywords:Earth and Planetary Sciences (miscellaneous), Earth-Surface Processes, Geography, Planning and Development
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hurst, Dr Martin
Authors: Dickson, M. E., Omidiji, J., Litchfield, N. J., Norton, K. P., Matsumoto, H., Krier‐Mariani, R. L., Horton, S. L., Acharya‐Chowdhury, L., MLlean, A. D., Hurst, M. D., and Stephenson, W. J.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Earth Surface Processes and Landforms
Publisher:Wiley
ISSN:0197-9337
ISSN (Online):1096-9837
Published Online:04 July 2022
Copyright Holders:Copyright © 2022 The Authors
First Published:First published47(13): 3019-3032
Publisher Policy:Reproduced under a Creative Commons licence

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