This is an EarthCache and has special requirements for logging it. You cannot log a Found It without responding to the logging requirements set out below.
Only one find claim per Message. Each Geocacher claiming a find must submit an individual response. One team can not lodge a response on behalf of a group of people.
Hopefully, after visiting this site, you will have an expanded appreciation of the wonders of our natural environment, and recognise that the environment here has a rather rare geological feature.
When walking here recently after an extended four days of rain in October 2017, I came across a sign at the bottom of the track that read: "Caution! Parts of this track will be slippery when wet."
So what was slippery? Mud or Clay, I guessed. Walking along the track, I soon came upon a slippery bit – not the usual rolling rock type: just stuff that looked like clay and ………
Everything geological, it seems, comes from rock. When rocks break down (called weathering – physical or chemical, but that’s another story), they can become silt, clay or mud.
Clays that are tan, brown or brick in colour contain iron oxide (e.g. terra cotta and stoneware) as the colouring agent. Clays that lack iron oxide are grey to white in colour (e.g. porcelain).
Note that another difference in clays is texture. Clays vary in particle size, and some are much coarser than others. Under pressure, these turn into siltstone, claystone and mudstone – sedimentary rocks.
Clastic (meaning composed of broken pieces of older rocks ) sedimentary rocks are classified by size of the sediment particles making up the rock. Particle size descriptions like sand, silt, and clay have specific meaning in geology and engineering
- Siltstone - greater than half of the composition is silt-sized particles.
- Claystone - greater than half of the composition is clay-sized particles.
- Mudstone - hardened mud; a mix of silt and clay sized particles.
Fine sand particles are about one sixteenth of a millimetre. Silt particles are about one one hundred and twenty-eighth of a millimetre, while Clay particles are about one two hundred and fifty-sixth of a millimetre. The Wentworth Scale is a very good chart of grain sizes.
Sedimentary rocks make up 75 percent of the rocks at the earth’s surface. Some of these are conglomerate, sandstone, siltstone, mudstone and shale (chemically formed sedimentary rocks include limestone, gypsum, coal and amber - but not around here).
Technically, mudstone forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are buried and compacted by overlying sediment hence forming mudstone. Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.
So, mudstones and shales are made of silt- and clay-sized particles that are too small to see.
The only difference between mudstone and shale is that mudstones break into blocky pieces whereas shales break into thin chips with roughly parallel tops and bottoms.
What tremendous geological forces must have been in play here millions of years ago to raise this area up!
Find GZ for this earth cache. It is on the track – don’t wander off into the bush. As a further reference, position yourself on the track so that you can see the forked tree in this photo on the left-side of the track walking down (right-side walking up).
To claim your “Found It” for this earth cache, answer the following questions:
- What do you see here – clay, silt or mud?
- Are the rocks mudstone or shale – justify your answer.
- Colours are vivid. Describe the colours you see.
- Describe the texture. Squeezing some of the particles between your fingers might be good.
And finally, take of photo of yourself OR your GPS to show a view of GZ. Include it in your message, but please do not post it in your log, it might give too much away.
When you have your response to the above, please, if possible, MESSAGE us, using the link at the top of the page underneath the name of the Cache. We prefer the MESSAGE method, as apparently, we don't respond to emails very well, but messages we do. We will contact you by MESSAGE once your MESSAGE has been received. But you can log your find in the meantime, and just say that you have MESSAGED your answers to the COs.
Happy Earthcaching!