09/04/2026
This months meeting on Tuesday 14th April 7pm we are delighted to receive Peter Frost, Science Support Service Whanganui as our guest speaker.
Peter is a prolifically interesting scientist with a wealth of knowledge and experience across a broad range. He recently presented the talk at our museum regarding our flora as likely effected by Moa.
He will be engaging us with the wonders of Granites and granite landforms and has provided the synopsis below. This is a rare treat for the club to have such a quality speaker.
Granites and granite landforms
Granites are plutonic rocks, formed deep inside the earth’s crust by the gradual cooling of magma upwelled into the earth’s crust and from crustal rock itself melted by the heat of magma hotspots below. This slow cooling produces large, visible crystals, mostly quartz and feldspars interspersed with shiny flakes of mica, giving granite its characteristic off-white, pink, or reddish colour. Although granite landforms are found throughout the world, sometimes resulting in dramatic monoliths—e.g., El Capitan and Half Dome in Yosemite National Park in the USA—this talk will focus on just one set of granites, those making up the Matobo and Chinamora batholiths in Zimbabwe. These are massive, 2.6–3.5 billion-year-old
Archaean rock formations, formed deep inside the earth’s crust and slowly exposed subsequently over millions of years as the softer overlying rock was etched away. Today, they are seen as bornhardts (sometimes referred to as whalebacks or dombos), surrounded by
tors or castle kopjes, products of both spheroidal and chemical weathering. Caves and overhangs, which are prominent features in granite landforms, are mostly formed by subaerial erosion. The resulting landscapes are home to a wide range of animals and
specialised plants, and have long been used by humans as shelters. The Matobo National Park in Zimbabwe has been designated a UNESCO World Heritage Site on account of the numerous caves bearing outstanding examples of African rock art. These paintings, dating as far back as about 13,000 years, were created primarily by early San hunter-gatherers. In this talk, I will describe these and other features of this landform with the aim of giving you
some insights into its formation and functioning.
Peter Frost
Science Support Service
Whanganui
