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Ultramafic Magnificence

A cache by Tim+Jed Send Message to Owner Message this owner
Hidden : 3/13/2011
1.5 out of 5
5 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

Ultramafic Magnificence


Those who claim this earth cache will certainly earn it- but what a reward it offers. So if you are interested in earth science and the wonder of the wilderness then this is for you -only problem- it takes three days to walk there!

Location and Conditions
The location of this EarthCache is on the boundary of Fiordland and Mt. Aspiring National Parks in New Zealand, at a spot known as COW SADDLE. Cow Saddle is the middle pass/saddle/col on a 5-8 day tramping route known as THE FIVE PASSES. To get there you need to be experienced in wilderness tramping a route (as opposed to the much friendlier DOC tracks). You must carry and be able to use all the necessary equipment including shelter, cooking gear and food, all weather clothing and emergency equipment. On this route there are no huts, marked or cut tracks or Department of Conservation personnel. You need to be able to handle river crossings, snow, map reading and navigation and all the weather that Fiordland and Mt Aspiring will throw at you. Being a wilderness area you are only permitted to walk to this spot- no landing any aircraft.

Ultramafic Rock
The Red Mountain range in this area of Westland is one of the most colourful and geologically interesting ranges in New Zealand and one of the more unusual world wide. It is made up of ULTRAMAFIC rock consisting of peridotite or dunite (the later named after the Dun Mountain in Nelson). ULTRAMAFIC rocks contain very little quartz or feldspar, and are composed essentially of ferromagnesium silicates (Iron and Magnesium). Because of this HIGH IRON CONTENT, these hills weather to a distinctive, beautiful, deep red, brown rust colour. Being deficient in Ca, Na, K, P, Bo and other essential minerals no vegetation grows on them, but they are not "toxic" as often reported, merely deficient in essential elements.

Red Mountain, as seen from above the upper Cascade Valley

Close up of Ultramafic rock on Fiery Col

The Red Mountain's ultramafic rock has been thrust up least 10 km from the magma below through the earth's crust to the surface by the tectonic actions of the Indo-Australian and Pacific plates. This action results in ultramafic rock appearing in isolated patches, surrounded by the more usual alpine rock of greywacke and schist. These colourful patches contrast dramatically against the surrounding rock and are known as ULTRAMAFIC INTRUSIONS.

Another striking effect of the tectonic process is readily apparent as you consider the distribution of ultramafic intrusions in the South Island. Geologically the other half of this Red Mountain range lies in Nelson, some 480kms to the north and is called Red Hills and Dun Mountain. In the past all these hills and miuntains were adjacent, but on either side of the alpine fault - Differential movement along the fault over time has lead to them being now far apart. (see map illustration of this below).

The cache owner at Cow Saddle (24 March 2011). Behind is a face of Ultramafic rock coming down off Niobe Peak. This location is some 30km south of Red Mountain

At Cow Saddle, the site of this cache, you can see exposed ULTRAMAFIC rock, where a huge face of it pours down to the saddle from the south east (see photo of me above). And then looking up an additional 500 vertical metres to the west you see the appropriately named Fiery Col where more ultramafic rock is visible. As you clamber over this rugged col and pass into the Olivine River Valley the differentiation of the red ultramafic rock to the east side of your path and the traditional greywacke scree to the west is striking (see picture below). On a practical level- for trampers the ultramafic rock is great to walk on- it is rough like sand paper and gives a great grip for your boots when you really need it. It also signals its presence with a distinctive brick like clinking when it bangs together under your footfall.

Google Earth image of landscape in this area, showing the relationship of the three ultramafic intrusions at Cow Saddle and Fiery Col (bottom centre) and the distant Red Mountain (top centre). View is looking North

Fiery Col from North- note the distinctive colour difference in rocks from one side to the other

Claiming the Cache
The cache coordinates are a location adjacent to an obvious ROCK set amongst some mountain tarns- If you are in that spot- hearty congratulations for getting there- and what a place to be! To log the find please e-mail me back with the answers to the following questions.

1- At the coordinates there is a Rock. What type of ROCK is it?
2- What evidence supports your conclusion to answer 1?
3- How do you think this ROCK got to this location?
4- What is the approximate size of the ROCK (Big House? Small house?, Dump Truck?, Mini bus?, Car?)
5- There is a nice big rounded rock immediately to the west of the ROCK (good for climbing and sitting on for lunch and drying out wet gear!)- approximately how far is the top of this sitting rock from the ROCK?

OPTIONAL- As well as the answers, if you can e-mail me a picture of you at the ROCK that would be a great (don’t put it in the gallery though, as that would spoil the questions for others).

AGAIN OPTIONAL- If the weather permits- please take a photo for the gallery of yourself at Cow saddle or Fiery Col with your GPS and some of the plentiful ultramafic rock. This will indeed be a good record of your mighty exploits. Any tales of your journey would also be most welcome in the log.

Travel Safely

This Geocache has been published with the permission of the NZ Department of Conservation.

Additional Hints (No hints available.)



27 Logged Visits

Found it 5     Write note 21     Publish Listing 1     

View Logbook | View the Image Gallery of 164 images

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Coordinates are in the WGS84 datum

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