These rocks were deposited as sediments, in a shallow marine environment nearly 800 million years ago.they were originally deposited horizontally in a deep trough called the Adelaide Geosyncline and were part of a sedimentary pile over 10 kms thick. The grainsize of the original sediments varied from mud (very fine), through silt (fine) to sand (medium to coarse), The compaction, dewatering and hardening of these sediments (called lithification) rwsulted in the formation of mudstones, siltstones and claystones.
About 500 million years ago there was a significant mountain building event that resulted in this area of South Australia being subjected to major folding and significant uplift. These rocks reacted differently to all this upheaval, depending on their grainsize.
At GZ you will find a sign,You are welcome to log a "Found it" log when you message or email the answers for the following questions. any "Found it" logs without the answers being sent will be deleted.
What is the groundwater rich in that seeped into the fractures of the rocks and what did it deposit ?
Describe the colours of the rocks around GZ and how they change in layers ?
How are the rocks different from one side of the track to the other ?
Do these rocks contain any fossils ? explain how you got your answer ?
Are these rocks classified as Hard or Soft rocks ?