Natural Features

Geology

The Otago Peninsula is the remnant of a shield volcano active approximately 10 to 13 million years ago. The Hereweka Harbour Cone property is composed mainly of volcanic rocks of the Dunedin volcanic group. The high points of Peggys Hill (401 m) and Harbour Cone (315 m) consist of hard basaltic lava flows.

Much of the property is underlain by volcanic ash and rubble, which weathers to clay-rich material. Combined with wind-blown loess that also mantles the Peninsula, this gives rise to the steep, rugged topography and widespread evidence of landsliding and erosion that characterises the property.

Conglomerate boulders are scattered throughout the landscape, ranging in size from approximately that of a basketball to that of a large vehicle. These were propelled skyward when the area served as a lateral vent during the volcano's initial eruption phase. The composition of cobbles and pebbles within these boulders matches rock formations in Antarctica, reflecting the shared geological history of New Zealand and Antarctica as former parts of the supercontinent Gondwana, which began separating more than 80 million years ago.

A fault scarp is visible as the eastern face of Peggys Hill. A small area of sedimentary rock, including limestone, is exposed at the southern end of the property near the site of the historic lime kilns.

Topography and Catchments

The property straddles the main Peninsula ridgeline and drains into two catchments: Smiths Creek on the harbour side and Stewarts Creek on the Hoopers Inlet side. Smiths Creek supports five species of indigenous freshwater fish and is considered a significant freshwater habitat. Both creeks support populations of the threatened kōura (freshwater crayfish).

Landscape Character

Grazed pasture is the dominant vegetation cover, with approximately 14% being indigenous woody vegetation. Stone walls, derelict structures, old shelter plantings of macrocarpa, hedgerows, and orchard remnants are visible throughout, reflecting the property's settlement history. The property wraps around three sides of Larnach Castle and is adjacent to the Otago Peninsula Trust's property containing historic lime kilns.

Harbour Cone's distinctive conical shape has made it one of the most recognised landmarks on the Peninsula. Its prominence has made it a subject for numerous New Zealand artists, including Dame Robin White, who lived in Portobello for several years and returned to Harbour Cone repeatedly in her work.