Chaotic Rocks - The Don EarthCache
Hidden : 11/29/2017
Difficulty:
1.5 out of 5
Terrain:
3 out of 5

Size: Size: other (other)

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Geocache Description:

The Terrain rating is because of the rock hopping you have to do to get to GZ.
With good balance and a bit of care it will not be a big issue.
Also the tide can make a difference so visiting at low tide will be much more enjoyable.

Here at Don Heads you will be visiting a fantastic geological phenomamon that we think is very deserving of an Earth Cache so other teams can also enjoy this location.
Near the mouth of the Don River there occurs about 500mts of Igneous Shore Platform which formed in the Tertiary period. This was caused by two massive flows that were Olivine rich and filled the course of the old Don River before Bass Straight waters rose about 25 million years ago.
In some places lava from the second flow filled cracks in the first flow. If you examine the fallen rounded sea worn rocks you may see some xenoliths in the rock. (xenoliths a piece of rock within an igneous mass which is not derived from the original magma but has been introduced from elsewhere, especially the surrounding country rock.)

These xenoliths show as a dense fine grained olivine nephelinite (like basalt) rock with peices of coarse "mantle" peridodite (mineral like olivine)
If you look as you walk to GZ you will notice the shore platform is made up polygonal Basalt Columns with the corners rounded by the salt water as well as a lot of basalt rocks that have been eroded by the wave action.

Depending on what level the tide is will depend on how close you can get to the outstanding Sea Stack.
From what ever distance you will notice this stack is made up of columnar polygon shaped basalt that were formed as the lava cooled.

To claim a find for this Earth Cache you will have to observe the area and answer the questions below and send us the answers, do not post them in your log.

Q1. The name of this Earth Cache.
Q2. In your own words explain how you think these basalt columns are standing where they are.
Q3. Now looking to your left from the stack you will see another lave flow. Did it cool into columns the same as the stack.
Q4. Did you see a xenoliths in the basalt you have been clambering over.

We hope you enjoy your visit.

Additional Hints (Decrypt)

Fvzcyl fraq hf gur nafjref gb gur dhrfgvbaf

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)


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