The present day features of this site are the result of a long history of landscape and soil formation. The soil here overlies 650 million year old Burra Group rock. The material that formed this rock was deposited in the midst of a 300 million year period, when an enormous thickness of sediment was laid down by water, wind and glaciers. Incredible upheaves from deep within the earth subsequently folded and distorted the rocks, forming huge mountains.
Long periods of erosion followed, eventually causing the landscape to be levelled.
40 million years ago the land was thickly covered by local sands. In the more recent geological times, heavy clays were laid down in lakes, gravelly clay alluvium washed out the Barossa Ranges, and accessions of marine origin calcium carbonate dust permeated the landscape.
At this site, the North Para River removed the overlying sand and clay, exposing the underlying rock to soil forming processes. The result is a soil profile with a topsoil of organic rich, dark coloured sandy loam over a lighter coloured layer with cemented quartz gravel, and a sub soil of acidic red clay with yellowish mottles. Below this is a greenish grey, alkaline, soft meta siltstone rock with red and yellow mottles.
To log this earthcache you must visit this sculpture and email me the answers to the following question,all answers are obtained from the plaque on the sculpture.
Q1: The sculpture displays the mottled colours which indicate prolonged wetness at depth and the long weathering history of the underlying rock, What is the dark surface layer highlighting?
Q2: What is the Australian Soil Classification?
Q3: What is this sculpture made from and what is the dimensions of the sculpture?
Q4: What is the soil profile at:
0-35cms? *Example Answer* (topsoil) acidic sandy loam
35-100cms?
100-140cms?
140-200cms?
200-420cms?