The posted coordinates are located on the ocean side of the tunnel,some crawling will be involved.Due to the surrounding your GPSr signal may be weak,GZ is located against the cliff wall on the right hand side as you exit the tunnel.
There are no hand rails or safety guarding at this site,you do not need to be near the edge to find your answers,however please be mindful of gaps, edges and drop-offs when visiting this area.
What Is Geological Time?
Geological Time is the method used to date the age of rocks and minerals that make up the Earth and all other planets.
Deep Time is concidered the overall age or time of the materials in the universe,this time is measured back as far as we know time to be some 13.8 Billion years ago,the beginning of all time,the time known as the Big Bang.
Some of the oldest minerals on Earth are found here in Australia dating or measuring back some 4.4 million years old,these zircon minerals have previously had an earlier life,as the zircon mineral had eroded,decayed and then redeposited into newer younger material,Most rocks on Earth have gone through this process.Some meteorites have been found on Earth that are 4.54 billion years old and Astronomers believe the Earth was formed at the same time as these meteorites so the given age of the Earth is 4.450.000.000 years old,thats 4.54 billion years old,only 1/3 of all Deep Time.
Geoscientist use 2 methods for recording Geological Time - Absolute and Relative.
Absolute Time is the age of materials and rock formations in the years before present.With scientist knowing the decay rate and half life of an atom they can determine the absolute time from Radiometric dating and then also Carbon dating.
Relative Time is an event or a period captured within Deep Time,the best way to understand Relative time is to think of it as time related to evolutionary events in Earths history such as the Permian Period 299-251 million years ago or the well known Jurassic Period from 199-145 million years ago.
How Old Is A Rock?
Relative time is best to describe the age of a rock.Sedimenary sandstone is formed over many millions of years.As sediment falls to the ocean floor it is then compacted downward from the water pressure above,over millions of years more and more sediment falls forming compressed layers,some minerals trapped inside these layers later react within the sediment bonding it together with a naturally formed cement.
Alot of these falling sediments are from material caught within Ice Glaciers.When these glaciers melted the sediments would fall to the ocean floor contributing to the making of sandstone.Larger stone caught in these glaciers and then dropped to the ocean floor are known as Dropstones.This is when a much older rock is caught within the development of younger forming rocks,
Sedimentry rock stratas are formed horizontally or very near so when origanally deposited,so knowing this when we are looking at sedimentry layers we know the bottom layer is much older then the next layer above,so making the top layer the youngest, unless the rock has been completly turned upside down.If the lines on a sedimentry structure are not sitting horizontally this is proof that the rock has been shifted or buckled from volcanic activity or uprising.Sandstone is made up from fragment deposits from much older eroded and broken down rocks.Radiometric dating in sandstone will determain the age from the deposited rocks and not the actual time the sandstone was formed,
Sedimentry layers from oldest to youngest
Buckled Sedimentry layers
Sea Caves and Tunnels
Sea caves and tunnels such as Gosang's can be found along coastlines around the world.A Littoral cave is formed by wave action in zones of weakness in sea cliffs,these weaker zones are more easily exposed to many types of erosion such as Hydraulic action from the pounding waves,Chemical erosion from chemicals found within water that can break down certain rocks like sanstone leaving a pitted effect similar to how rust eats at metal,then there is Wind erosion where the wind pushes against a surface dislodging and moving away small fragments leaving a smooth bowl effect.Often these weaknesses are faults , dykes or bedding plane contacts.Some wave cut caves can now be found way above sea level due to later uplift or from the sea subsiding
With scientific studies from Carbon dating and Fossil Indexing we know the land formation here was formed and shaped during the Permian period so as you enter the tunnel and move towards GZ you can concider yourself going back 299 million years of Geological Time.
Earth Lesson Questions - all answers are found from observations at the posted coordinates.
1 - What is the main feature here that had influence in the construction of the tunnel?
2 - Do you see evidence here of chemical erosion,if so where?
3 - You will find a feature here just above head height,what is the feature?(a,b or c) measure its approximate size in height and width?
a - wind erosion
b - chemical erosion
c - dropstone
4 - Looking west you will see the sedimentry layers here that make up the formation.If we assume the layer at sea level is 299 million years old,and each layer takes approximately 10 000 years to form,How old is the rock platform from where you are currently standing?
5 - Have the standing rock structures here been distorted or moved, or does it still sit horizontally?
6 - (Optional)Post a pic of yourself or your device from the posted coordinates(please no spoilers)
Please message or email your answers to me via Geocaching.com,you do not need to wait for a reply to log your find,however any unsatisfactory logs will be deleted.