Mersey Bluff EarthCache

This cache has been archived.

Tealby: After receiving a very abusive email from a new cacher who failed to comply with the EarthCache listing, I have decided to archive this cache to avoid any repeat performance - I'm afraid that I am not prepared to monitor compliance with the EarthCache logging requirements if I risk receiving such abuse when I delete a log as I am obliged to do so.

I trust that all cachers who have been to this picturesque spot have enjoyed themselves - there are other physical caches nearby for future visitors to enjoy (including a great multi).

More
Hidden : 1/23/2007
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size: not chosen (not chosen)

Join now to view geocache location details. It's free!

Watch

How Geocaching Works
Looking for a different adventure?

Please note Use of geocaching.com services is subject to the terms and conditions in our disclaimer.

Geocache Description:

This area is part of the Tasmania’s Great Nature Trail, which starts near here, and travels across the north coast ending past my other Tassie EarthCache at Stanley to the “Edge of the World”. This trail covers a truly spectacular part of the state and also has some wonderful geocaches! The Tiagarra Aboriginal Cultural Centre and Museum is also located at the Mersey Bluff.

At Mersey Bluff you will find a headland of dolerite rock. This rock dates back to the Jurassic Age, 185 million years ago.

Dolerite is a type of igneous rock, which is formed from melts in the Earth's crust. Igneous rocks are classified using grain size, silica content and/or silica saturation.

Grain size reflects the depth at which the molten rocks form in the Earth:
- Volcanic rocks form close to the surface, cool quickly and form fine grains/crystals.
- Plutonic rocks form deep in the Earth, cool slowly and form coarse grained rocks.
- Sub-volcanic rocks form at intermediate depths, generally in dykes (vertical sheet of intrusive igneous rock) or sills (horizontal sheet of intrusive igneous rock) and form medium grains. Intrusives are when igneous rocks have intruded other rocks.

Most people know of basalt, which is the most common volcanic rock on Earth. Dolerite is the sub-volcanic equivalent to basalt.

The dolerite rock at Mersey Bluff formed as a sill (or horizontal) intrusion, faulted down, to Bass Strait. The rock cooled giving joints and fractures. Some joints are like “packs of cards”. When the rock has eroded it has provided flat surfaces for seating for Tasmanian aboriginals. They also carved inscriptions/engravings onto the rock, known as petroglyphs. Over 200 petroglyphs are located in the Mersey Bluff area, and 10 are on show to the public. The listed coordinates will take you to one of these petroglyphs (near #9 post marker).

To claim this cache you need to email me with the following information/answers:
1. the shape of this petroglyph,
2. the colour of the lichen growing on the dolerite rocks (some of the lichen is green as expected, but what is the other colour?), and
3. are there any visible crystals (also known as diabase for American visitors) in the dolerite rock?

I am happy for you to log your visit in anticipation of my confirmation; however, if I do not receive your email with the correct information I will be obliged to delete your log.

Your log should indicate how many people were in your party and include a photo of your visit to this picturesque area. Obviously your log, including any photos, should not give away either of the answers. Photos of other petroglyphs are OK, just not #9.

For further information on igneous rock formation visit the Australian Museum Online at (visit link)

Additional Hints (No hints available.)



Advertising with Us

Inventory

There are no Trackables in this cache.

View past Trackables

What are Trackable Items?

Bookmark Lists

View all bookmark lists...