Abstract
This thesis investigated the contemporary processes and origins of Te Taero a Kereopa/Te
Tahuna a Tama-i-ea The Nelson Boulder Bank. The Nelson Boulder Bank is an aesthetically
and geomorphically significant coastal landform in Whakatū Nelson, Aotearoa New Zealand.
A 13 km long gravel barrier, the Boulder Bank is also unique at a global scale. This is due to
the length of the barrier, the extent of its low-tide coarse-clastic platform, and that it is situated
in the relatively protected, fetch-limited wave environment of Tasman Bay. There are two
competing models for the origins of the Nelson Boulder Bank: the longshore drift model and
the in situ-transgressive barrier model. Both models are informed primarily by morphosedimentary
data, however, data on the coastal processes operating on the Boulder Bank is
lacking. As such, this thesis addressed this knowledge gap by observing short (< 3 months) and
medium (< 17 years) term geomorphic change at the Boulder Bank. Fieldwork for this thesis
was conducted from 18/02/23 – 19/05/23, utilising an Unmanned Aerial Vehicle (UAV) and
various post-processing analytical methods. A wave-like propagating pattern in erosion and
deposition was discovered on the ridge of the Boulder Bank, likely representing the longshore
drift of fine clasts and a morphodynamic feedback process. Coarse clasts were predominantly
mobile on the Boulder Bank in a southwest direction alongshore, with an increasing onshore
component towards the barrier terminus. As such, this thesis demonstrated several mechanisms
of longshore drift. It was found that the ridge is likely a Holocene landform. However, on the
platform, it is unclear if the longshore transport of clasts was a developmental process. For
much of the Boulder Bank, the platform was essentially immobile. In addition, the morphosedimentary
architecture of the Boulder Bank suggests substantial transgression in its past. The
platform may be a product of two or more interglacial periods. Therefore, neither the longshore
drift model nor the in situ-transgressive barrier model explain the origins of the Boulder Bank.
This thesis categorises the Nelson Boulder Bank as a ‘badass’ landform to attempt to explain
why its origins are difficult to reconcile. A law-place-history triad may explain the origins of
the Boulder Bank. As universal laws likely apply to all landforms, the unique environmental
and historical contingency of the Nelson Boulder Bank determined its origins. This thesis
recommends that future research on the origins of the Nelson Boulder Bank employ the badass
framework for geomorphic systems.