The Pinnacles EarthCache
Hidden : 10/24/2017
Difficulty:
1.5 out of 5
Terrain:
1.5 out of 5

Size: Size: other (other)

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Geocache Description:

A 2km drive on a good sealed road heading to the Maclean Lookout will take you to the Pinnacles 

Great views over looking the  Township of Maclean The Clarence River  and out lying areas can be seen from gz 

This is a very simple Earthcache answers can be obtained from description or by viewing the Pinnacle 

Composed mainly of sand sized mineral particles of rock The Pinnacle Rocks and nearby cliff are composed of Cretaceous -Jurassic Kangaroo Creek Sandstone ,over laying Jurassic Siltstone of the Walloon Coal Measures 

There are a number of examples in the region where the boundary of the Strong Sandstone overlaying the weaker Siltstones has led to major landslips 

This is usuall triggered by Intense Rainfall or possibly a minor Earthquake 

Pinnacle Rocks are formed by a cliff line collapsing into a pile of large boulders which are strewn down the hill side for 100&'s of metres 

Part of the cliff has slid down intact without collapsing producing The Pinnacles that we see today 

 

JURASSSIC PERIOD

The Jurassic Period ended 145 million years ago. In this period the Earth's climate changed from hot and dry to humid and subtropical 

Resulting in lush vegetation and abundant life ,many dinosaurs  emerged .

Crumbling land masses and inland seas changed the face of the earth 

SILTSTONE 

Siltstone and shale are sedimentary rocks formed in ancient marine environments

They are mud rocks composed of silt and clay particles slowly deposited through suspension in calm waters 

Silica and calcium carbonate from marine creatures provide the cement necessary to eventually form the rock 

 

CRETACEOUS PERIOD 

This period followed on from the Jurassic Period and spanned 79 million years 

This period was a time of great inundation by shallow seas that created swamp conditions favourable for the accumulation of Fossil Fuels at the margin of the land area 

Coal bearing strata are found in some area of Australia,Siberia ,New Zealand ,Mexico and west United States 

SANDSTONE 

Sandstone is a classic sedimentary rock

Composed mainly of sand sized particles of rock fragments(0.0625 to 2mm)

Mainly comprising of quartz and feldspar,this is because they are most resistant to the weathering process at the earths surface 

 

To log this cache you must forward answers to the below questions 

I will delete log entry if I do not recieve answers 

 

Q1   Explain in your own words how the Pinnacle has formed 

Q2   Which was formed first the Sandstone or the Siltstones ,give your reason why 

Q3    How many rock layers form the Pinnacle 

Q4    Has man changed the appearance of the Pinnacle ,if yes how?,this question is to prove that you were at gz 

Take the time to drive up to the Lookout after spectacular views await you 

 

 

Researched information 

Cretaceous Period Facts and information  National Geographic (national geographic.com/science/prehistoric)

Jurassic Period Facts and Information National Geographic                           
What environment is likely to form siltstone or shale ?Sciencing (visit link) )

Sandstone rocks (visit link)

Council Information board at GZ

Congratulations ChrisDen on FTF 

Additional Hints (No hints available.)



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