Document ID: chunk:federal_register_of_legislation:F2025L00287:reg:3:p17
Version: federal_register_of_legislation:F2025L00287
Segment Type: reg
Provision Reference: reg 3 (pt 17/276)
Character Range: 57637–60385

ha are protected in a network of 18 public reserves, most of which are located along the coastline.

1.2.2        Geology and geomorphology
Norfolk and Phillip Islands are small remnants of a large volcano that developed on the Norfolk Ridge. The volcanic landmass of which they are a small part was created during several eruptions between 3.1 and 2.3 million years ago (Jones & McDougall 1973). Nepean Island, located between Norfolk and Phillip Islands, is not volcanic in origin and is composed of calcarenite (a form of limestone). It was formed from windblown sand dunes during the last two ice ages (Jones & McDougal 1973; NIP & FS 2003).
One of the two main volcanic vents was in the vicinity of Mt Bates (318 m above sea level) and Mt Pitt (316 m above sea level), which now stand as the two highest peaks on the main island. The other significant geological feature is the southern plateau, formed from horizontal sheets of basalt, which occupies most of the main island and is dissected by deep narrow valleys (Jones & McDougall 1973). There is a smaller plateau in the north-west near Duncombe Bay. The fourth physical region is the coastal lowland around Kingston, comprising the land formed by infilling behind the calcarenite barrier (Abell & Falkland 1991). Precipitous cliffs surround the island and most of the valleys hang over the cliffs, suggesting that wave action has been the most important force in shaping the features of the landscape.
Surface water is restricted on Norfolk Island, with no lakes and few wetlands. The three permanently flowing streams on the southern side of the island are relatively small compared to the valleys they occupy, suggesting that they were largely eroded during a wetter period. These three streams are the only creek lines that drain down to sea level. The northern portion of the island has only sparse and intermittent creek lines.
Groundwater flow systems are localised, following the major drainage basins, with vertical drainage through the weathered volcanics leaking into the underlying agglomerate and basalt aquifers, which are generally hydraulically interconnected (Petheram et al. 2020). Recharge occurs across the elevated portions of the island, including the southern and northern plateaus. A high-level water table with hydraulic potential occurs under the southern plateau at a height of over 100 m above sea level (Petheram et al. 2020).
On Phillip Island there are three (possibly four) volcanic vents. At 280 m, Jacky Jacky is the highest point on Phillip Island with steep cliffs fringing the perimeter. There are no permanent streams on the island. The tuff and ash beds are very friable and sensitive to erosion. There has been severe erosion on Phillip Island as a