Margaret Brocx

The focus of this Thesis is geoheritage of the coastal zone, and thus coastal geoheritage. The coast is one of the most complex environments on the Earth’s surface being a zone of intersection and interaction between land, sea, groundwater, and atmosphere. The geodiversity developed along the coast is variable depending on parent rock types, sediments and other materials, local biodiversity, hydrochemical effects, and diagenesis, and variable according to environmental setting and climate. As such, the coastal zone presents complicated products of erosion, sedimentation, biogenesis, and diagenesis, and well-exposed wave-washed, sediment-scoured, and salt-weathered rock sequences. With its complexity and variability, the coastal zone lends itself to developing principles, classifications, and procedures for geoheritage, geoconservation, and policy to protect sites of geoheritage significance. The coastline of Western Australia is an ideal starting point for the development of a classification of coastal types and for the development of principles for coastal geoheritage because it manifests a wide variety of coastal forms along its 6000 km length and 22° of latitudinal range. It transcends a diverse range of geological regions and several climate zones (from tropical to near-temperate, and humid to arid), encompassing large tracts that are rocky and erosional versus sedimentary and depositional, and fronts various oceanographic and coastal settings (from macrotidal to microtidal, from wave-dominated to tide-dominated to protected, to wind-dominated). The approach in this Thesis is original in that, for the first time, there is a holistic study that identifies the significance of the coast for its geoheritage values. From forty-four sites described along the Western Australian coast, as well as information from literature review, a new coastal classification was developed, tailored for purposes of comparative geoconservation. Twelve coastal types were identified, categorised as inundational, erosional, depositional, biogenic, and diagenetic types, and their combinations. In addition, a Geoheritage Tool-kit was developed to establish a category-based inventory for identifying and assessing sites of geoheritage significance. The Geoheritage Tool-kit is applied to a selection of four large-scale and four small-scale sites. Outcomes of this study resulted in the development of concepts, principles, approaches and methods, and classifications with the objectives of identifying, selecting, and assessing coastal sites of geoheritage significance within Western Australia. Within a National legislative framework in Australia that is biocentric, and a Draft National Heritage Strategy that does not encompass geoheritage, policy specific to Western Australia and the coastal zone was developed in this Thesis. This policy incorporated overall themes and philosophy of geoconservation with principles and criteria adapted from overseas. More specific policy/policies were designed, tailored to site-specific geological regions, local geomorphology, and hazards resulting from oceanographic and biogeographic setting.