Encased Rock & twigs
Layers in Profile
|Class:||Crust (Crust) - Crust (Crust) - Crust (Crust)|
|This Photo:||Layers Cleaved Open|
General Species Information:
Found on Ellura (in the Murray Mallee, SA) and elsewhere
This is here to show the difference between the organic Microphytic crust & the calcrete layer (duri-crust) formed when calcium/limestone leaches up from below.
A millenia ago Ellura was under the ocean and a limestone shelf was created from dead shellfish, etc. This limestone shelf is up to 60m below. The calcium from the limestone shelf leaches up and crystallises around rocks and branches near the surface creating another shelf, this time calcrete. Same minerals, different process
There is also another form of calcium deposits here called Stromatolites which is created from a different process again.