Mount Titiroa

The white granite that forms the summit and high ridges of Mount Titiroa was formed as liquid magma at 10 - 15 kms depth along an extended line on the margin of Gondwana about 120 million years ago. These magma chambers fed a chain of volcanoes at the surface above them. This chain of magmatism can be traced through New Zealand to Queensland (Australia) and also Antarctica. At this location the overlying rocks have all been eroded away to reveal the fossilised magma, now crystaliised into granite. Weathering has broken down the granite into scattered and piled up boulders and further into loose sand, containing crystals of feldspar, quartz and biotite mica. If you have ever been on holiday to Kaiteriteri near Nelson, you may be interested to know that the beach sand there is derived from exactly the same granite type as here, about 500kms away.

This is a great place to explore the maze of sculpted rocks - a photographers paradise! You will notice that on some of the granite surfaces there are bowl shaped depressions. These have taken tens of thousands of years to form by the action of freezing and thawing of ice on the rock surface. Think about how many of the boulders are rounded in shape whilst others are splintered into thin slabs. What might cause this difference? You will also notice that the light coloured sand that you are walking on is made up largely of crystal fragments - mainly feldspar. Can you find some nice specimens that show clear crystal faces?