Improbable Fossil Stones EarthCache
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Introduction. This street exhibition is a most unlikely
geological occurrence created for the sake of art.
Fossil Stones
This exhibition is called Fossil Stones.
Bluestone is a common building material in the city of Melbourne
but here you will find twelve large 'bluestone' boulders sitting on
the pavement. Upon closer inspection you will also find ten other
allegedly, but very improbable, geological features= the fossils.
Bluestone Australian bluestone is a volcanic basalt or
olivine basalt.
In Victoria, Australia, bluestone was one of the favoured building
materials of the 1850s during the Victorian Gold Rush.
In Melbourne it was extracted from a quarry in the Clifton Hill
area and used extensively in the 19th century. Because the material
was difficult to carve, it was predominantly used for warehouses
and the foundations of public buildings. Significant bluestone
buildings include the Melbourne Gaol, HM Prison Pentridge, St
Patrick's Cathedral, Victoria Barracks, Melbourne Grammar School,
Deaf Children Australia and Victorian College for the Deaf, Royal
Victorian College for the Blind, the Goldsborough Mort warehouses
(Bourke Street) and Timeball Tower. It was also used extensively
for cobblestone roads, many which still exist in some of
Melbourne's smaller lanes as well as walls, bridges, curbs and
gutters in many of the inner suburbs. Some examples of structures
that use the material include Princes Bridge and Federation Wharf
and Hawthorn Bridge. Because of its distinctive qualities,
post-modern Melbourne buildings have also made use of nostalgic
bluestone, including the Southgate complex and promenade in
Southbank, Victoria and apartments such as the Melburnian.
Bluestone was also sourced in many other regions of the Victorian
volcanic plains and used in towns and cities of central and western
regions including Ballarat, Geelong, Kyneton, Port Fairy and
Portland.
When ships arrived at Melbourne laden with passengers and/or
cargo, they would normally depart with less in weight that what
they arrived. This would lead to instability of the vessel if they
should continue their outward voyages, so they were loaded with
‘ballast', small bluestone pieces called ‘spalls'. With limited
dock and wharf space available, a vessel could not simply lie at
wharf till the ballast was loaded hence the ballast craft were
required to ferry the stones to the ships at anchor. It would be
stretching the imagination to suggest that they had a romance of
their own, but there was a culture, a bond, sometimes tenuous,
between the ballast men.
Williamstown was the original site for Melbourne's first settlers.
Many of the first ships arriving from the UK laden with settlers,
stock, building materials etc. returned to England with
Williamstown mined bluestone as ballast.
EarthCache Twelve basalt boulders are sitting on the street
pavement here ( which is also made of Bluestone slabs). Compare the
pitted texture of the pavement slabs with the fresh faces of the
boulders. These pits are known as vesicles which were gas filled
cavities in the molten lava prior to cooling and
crystallization
To log this Earthcache you are required to email Geodirect
with the answers to the following. Do not post the answers online
and do not log your find until you have received confirmation.
Unconfirmed logs will be deleted
A Explain why the ten 'fossils' are geologically
improbable,
B Identify / Name one fossil that can fly and one that is
sleeping
C Provide the year when these boulders were placed
here.
Additional Hints
(No hints available.)