I have a correction to my previous post referring to the Coquina shells
of Shark Bay. I was right in saying they were cockle like in fact after
visiting the Discovery Centre at Denham and further reading I learned that ‘Coquina’
is Spanish for Cockle. However it is in fact the cemented together mass that is
referred to as Coquina Rock.
Following is an extract from one source.
It is thought that this
cockle was first deposited here about 4000 years ago. Over the years the shell
deposits have cemented to form soft coquina limestone. Rainwater repeatedly
dissolves small quantities of calcium carbonate of which the shells are composed.
As the water evaporates, the calcium carbonate is precipitated as calcite
crystals, which bind the shells together. Coquina limestone blocks have been
used to build many of Shark Bays old buildings. These blocks have very good
insulation characteristics. A coquinite quarry can be visited at Hamelin Pool,
adjacent to the historic Telegraph Station.
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