Mount Titiroa

BY ROSE TURNBULL (GNS)
Accessibility: DIFFICULT
Rock basins, J.Thomson / GNS Science
An ancient Gondwana magma chamber that has been eroded into a wonderland of scattered pinnacles and weirdly shaped boulders.
Granite pinnacles, J.Thomson / GNS Science
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.
The southern slopes of Mt Titiroa, J.Thomson / GNS Science
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?
Directions/Advisory

About 4 kms east of Manapouri, take Weir Road towards Tuatapere until it joins with Blackmount - Redcliff Road. Continue south until you see a sign for Lake Monowai. Follow this road for 11.5 kms until you reach Borland Lodge. Here you will park your car and start walking!

This is a remote alpine environment. Be prepared for all weather conditions. Requires strong route finding and bush skills.

Accessibility: DIFFICULT

Follow the track to North Borland Hut (approx 6 hours) and from there it is a two to three hour 'bush bash' uphill to the ridge below Mt Titiroa Peak. The area of tors and boulders is about 3 kms south of the summit. You will need to be informed (DOC) and prepared to navigate this access route.

Features
Plutonic Landform Active Erosion
Geological Age
About 120 million years old
Zealandia Evolution Sequence
Eastern Province (Mesozoic growth): 300 – 110 million years ago