Camper's resident geologist
takes a bite out of the Big t.
Words and picsdavid cookThese may seem to be esoteric sorts of figures,
but they do potentially impact on your camping
trips and your ability to find someone’s address
via your GPS. It is necessary in this time of
extremely accurate GPS mapping to adjust our
global position to reflect our true location. It really
doesn’t make that much difference to your street
navigation, but for the military, aviation, mining
and agricultural activities using extremely accurate
navigation systems that 1.49 metres can make a big
difference.
Our position has actually been adjusted four
mes in the past 50 years, the remapping in 1994
oving us, officially, by a total of 200 metres.
These sorts of figures also have significance
r our northern neighbours, as our northward
ift causes considerable volcanic and tectonic
tivity in Indonesia, New Guinea and the Solomon
nds. The most recent earthquake in New Guinea
ulted in a 7.5 magnitude shake and over 120
hs in February this year.
he Great Australian Bight is the longest ice-free
west coastline in the world.
terestingly, the International Hydrographic
nisation does not recognise the Great
ralian Bight as a separate entity, and shows itTHE GREATAUSTRALIANBIGHTt.Or
AustAn aquaculture pod set
in the Southern Ocean's
pristine watersTHE GREAT AUSTRALIAN BIGHT is a left-over
geological remnant from one of the greatest
movements in Earth’s history. Its familiar sickle-
shaped 'bite' shape forming as a result of Australia
and Antartica, as we know them today, breaking
from the supercontinent Gondwana to create two
distinct continents. It was a process that began
around 70 million years ago — about the time of
the extinction of the dinosaurs — and finished
around 40 million years ago, as part of the natural
process known as rifting.
This rifting, which moves continental and ocean
plates around the surface of the globe and brings
internal heat to the surface, has seen Australia
travelling northward at the relatively rapid rate
of about 69mm per year, and rotating in a gentle
clockwise motion. This means we have moved a
total of 1.49 metres closer to the tropics in the past
12 years. No wonder it seems to be getting hotter
around here!
In comparison, North America only moves about
25mm per year, though it is being squeezed by 75
to 100mm per year by the Pacific Plate, resulting in
further lifting of the Rocky Mountains, the activity
of a total of 92 volcanoes in Canada and the USA
and the sort of tectonic activity that occasionally
trips fracture lines such as the famous San
Andreas Fault.