Abstract Two spectacular cliff lines occur along Australia’s south and west coasts: the Great Southern Scarp (new name) and the Zuytdorp Cliffs. Detailed measurements of their length show that they are exceptionally long and unusually continuous. The Great Southern Scarp is the southern edge of the Nullarbor Plain’s Bunda Plateau; it is cut into shallow marine sediments and extends for 820 km. Once a continuous sea-cliff, local uplift has isolated two sections from the ocean, so it now comprises the Bunda Cliffs (210 km of coastal cliff, 180 km of which is uninterrupted cliff line), Hampton Range (inland; 300 km), Baxter Cliffs (160 km of coastal cliff) and Wylie Scarp (inland; 160 km). The Zuytdorp Cliffs are coastal cliffs cut into eolianite, and extend for 210 km with an uninterrupted section of 120 km. The length of the Great Southern Scarp and the Zuytdorp Cliffs results from an unusual combination of circumstances. They are both composed of poorly jointed, relatively homogenous biogenic calcarenites, presented to high-energy ocean waves by regional uplift. The carbonates are sufficiently well cemented to maintain a steep vertical cliff face, but susceptible to disintegration under direct wave attack. Cliff retreat has been fairly uniform because of the broad spatial scale of both lithology and erosion. The arid climate, absence of nearby non-karstic catchments and karstic nature of the cliffs’ hinterlands has discouraged integrated drainage development, so no significant fluvial systems dissect the cliffs; this is a key factor in cliff edge preservation. In the case of the Great Southern Scarp, these processes have formed the longest continuous cliff line in Australia and probably the world. Referenced against criteria from Australia’s National Heritage List, the cliffs have potentially international/national levels of significance for the rarity of their scale, their demonstration of landscape evolution, and their spectacular beauty. KEY POINTS Australia’s longest coastal cliffs, the Bunda (SA) and Zuytdorp (WA) cliffs, are equal in length (210 km, within defined confidence levels). The Bunda Cliffs are part of the Great Southern Scarp (new name), an 820 km-long feature of the Nullarbor Plain that also includes the coastal Baxter Cliffs (160 km in length) and two paleocoastal scarps. The unusual continuity of the cliff lines results from a landscape history specific to the Australian continent, and the Great Southern Scarp is likely to be unusual on a global scale. The Great Southern Scarp and the Zuytdorp Cliffs have potentially national and/or international levels significance for geoheritage values in the criteria of events and processes, rarity and aesthetics.

中文翻译：

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澳大利亚最长海岸悬崖线的起源、地貌和地质遗产潜力

摘要 澳大利亚南部和西部海岸有两条壮观的悬崖线：大南部悬崖（新名称）和祖特多普悬崖。对它们长度的详细测量表明它们异常长且异常连续。大南部悬崖是纳拉伯平原本达高原的南缘；它被切割成浅海沉积物，延伸820公里。曾经是一个连续的海崖，局部隆起将两段与海洋隔离开来，所以它现在包括本达悬崖（海岸悬崖 210 公里，其中 180 公里是不间断的悬崖线）、汉普顿山脉（内陆；300 公里）、 Baxter Cliffs（160 公里的海岸悬崖）和 Wylie Scarp（内陆；160 公里）。Zuytdorp悬崖是切割成风吹石的沿海悬崖，绵延210公里，不间断的一段为120公里。大南部悬崖和祖特多普悬崖的长度是由不同寻常的情况组合而成的。它们都由连接不良、相对均质的生物钙质钙质组成，通过区域隆起呈现给高能海浪。碳酸盐岩胶结良好，可以保持陡峭的垂直悬崖面，但在直接波浪冲击下容易崩解。由于岩性和侵蚀的广泛空间尺度，悬崖后退相当均匀。干旱的气候、附近没有非岩溶集水区以及悬崖腹地的岩溶性质阻碍了综合排水系统的开发，因此没有重要的河流系统剖析悬崖；这是悬崖边缘保护的关键因素。在大南部陡坡的情况下，这些过程形成了澳大利亚乃至世界最长的连续悬崖线。参照澳大利亚国家遗产名录中的标准，这些悬崖因其规模的稀有性、景观演变的展示和壮观的美丽而具有潜在的国际/国家级意义。要点 澳大利亚最长的海岸悬崖 Bunda (SA) 和 Zuytdorp (WA) 悬崖的长度相等（210 公里，在确定的置信水平内）。本达悬崖是大南部陡崖（新名称）的一部分，这是纳拉伯平原 820 公里长的特征，其中还包括沿海的巴克斯特悬崖（长 160 公里）和两个古海岸陡崖。悬崖线不寻常的连续性源于澳大利亚大陆特有的景观历史，大南部悬崖在全球范围内很可能是不寻常的。在事件和过程、稀有性和美学的标准方面，Great Southern Scarp 和 Zuytdorp Cliffs 对地质遗产价值具有潜在的国家和/或国际意义。