The Napier Mountains are a group of close set peaks, the highest being Mount Elkins, at about 2,300 meters above sea level.

The Napier Mountains were discovered in January 1930 by the British Australian New Zealand Antarctic Research Expedition under explorer Douglas Mawson.

Radiometrically dated to as old as 3.8 billion years, some of the zircons collected from the orthogneisses of Mount Sones are among the oldest rock specimens found on Earth.

Using a lutetium-hafnium (Lu-Hf) method to examine garnet, orthopyroxene, sapphirine, osumilite and rutile from this UHT granulite belt, Choi et al determined an isochron age of 2.4 billion years for this metamorphic event.

[4] Using SHRIMPU–Pb zircon dating methodology, Belyatsky et al determined the oldest tectonothermal event in the formation of the Napier Complex to have occurred approximately 2.8 Ga.[5] Preservation of the UHT mineral assemblage in the analyzed rock suggests rapid cooling, with closure likely to have occurred for the Lu-Hf system at post-peak UHT conditions near a closure temperature of 800 °C.

UHT granulites appear to have evolved in a low Lu-Hf environment, probably formed when the rocks were first extracted from a mantle profoundly depleted in lithophile elements.