Shell Hill EarthCache
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As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org
Shell Hill was so named because of the deposit of oyster shells, which in some cases were 6 metres thick. Shell Hill was formerly part of a shallow sea occupying the Murray Basin.
The deposit is said to be (Question 1) million years old and is the only one of its type above the surface of the earth in the southern hemisphere.
Due to storms and slow sinking of the Basin, the oysters would die and be covered by another layer, building up over thousands of years.
These ancient deposits were once under threat from farmers using the shells with super phosphate on their farms and councils for road building.
A firm called Ellis & Clarke realised the value of the shell as a fertiliser and work commenced in 1931.
A crushing plant was setup in the gully below with a chute approximately 50 metres long to feed the plant with shell. The crusher had steel blades which turned at great speed. So hard was the shell that the blades had to be changed every eight hours and sent to Adelaide to be rebuilt.
The crushed shell contained a high percentage of (Question 2) and was added to soil of clay structure to cause flocculation of particles to enable agricultural pursuits, especially in the hills and northern areas.
The late Sir Thomas Playford used a great quantity for his orchards in the Adelaide Hills.
After a few years the quarry closed, reopening in 1942 and finally closing in 1946. The area is now known as the Shell Hill Reserve and contains picnic tables and a number of walks through the valleys.
To log your find you will need to send me an email with a few answers to the questions below:
Question 1. How many million years ago is this deposit said to be?
Question 2. What does the crushed shell have a high percentage of?
Question 3. Compare the oyster shells in the hill to the oyster shell that you can buy at the fish shop today - is there any difference after millions of years.
Although not required, pictures at the hill are welcome
Additional Hints
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Treasures
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