We’re back with Anita and Roger Palmer of GISetc and Gary Lewis of the Geological Society of America for part 2 of their trip leading 19 educators and students in an investigation of Australia’s singular geography and geology.
Our group could not imagine enjoying anything more than the time we spent in the Sydney Basin, but forge on we did!
After breakfast with the koalas at Sydney Wildlife World, we flew to the northeastern coast of Queensland, Australia. We landed in Cairns (pronounced “Cans”), a beach town that is the launching off point for many adventures.
We were reminded of the enormity of Australia as we traveled to
areas that were quite different from the typical picture of the “arid
red continent.” The arid latitudes are the controlling feature of the
vast majority of the continent, yet the northern part of Australia
extending from 18° south to 10° south is quite tropical.
These lower-latitude lands (located farthest north on the continent)
offer a striking contrast to the rest of the continent in that they are
lushly covered in vegetation and have an abundant supply of
biologically diverse animals and deeply entwined communities of life. A
tropical rainforest dominates the landscape, and, along the shoreline,
hybrid biomes can also be found, such as mangrove swamps and grassland
estuaries of equal robustness. To help us understand the diversity, we
visited the Daintree National Park, much of which is covered by the
Daintree Rainforest, and toured the canopy. With the richness of life
around us, it was surprising to learn how poor rainforest soils
actually are. Rainforest soils require an intense recycling of
nutrients from decaying biomass to enable the richness of life to
thrive. Our guide reminded us that if the trees are removed or the land
cleared, the sophisticated web of life that hangs from these branches
would collapse, requiring a complex and long-term chain of events to
restore the area.
Cattle ranching and sugar cane shoots in the areas on the way to Daintree National Park from Cairns
The mythical-looking cassowary is one of the birds that lives in the
national park, and is indeed becoming one of the casualties of habitat
loss and other factors in the Daintree Rainforest. There may be as few
as 1500 cassowaries left in the world to date, so, try as we might, we
never caught site of this wonderful creature in the wild. Of
course, there is a tremendous movement to protect the cassowaries and
all indigenous species in the Daintree National Park.
Cassowary at Sydney Wildlife World
The ocean has a similar story of poor nutrient support at the base of
the food chain and efficient recycling of nutrients. To illustrate
this, our group spent the day diving and snorkeling on the Great
Barrier Reef. All who were on the boat appreciated the crystal-clear
waters for swimming, but we were surprised to discover that those very
waters are poor sources of nutrients for most plants and animals along
the reef. The reef community demands that any nutrients stored in
animals and plants be recycled efficiently and completely up the food
chain. The clear waters carry very little to feed plants and animals,
so animals like the coral must host plants such as algae within
their structures. The algae, in exchange for feeding the coral, are
protected from most predators that crawl or swim across the reef. So,
the two amazingly diverse systems on land and in the ocean–rainforests
and coral reefs–are actually quite similar.
We finished the day over dinner in the park alongside the shore,
talking about how processes on the coral reef we had just swum over
made our earlier visit to the Jenolan Caves (Installment 1) possible.
The inland sea that encouraged coral deposits that became the Jenolan
Caves disappeared when the eastern side of Australia was uplifted.
These deposits were eventually exposed and eroded slowly to form the
fantastic formations we experienced during our trip to the Sydney
Basin. Perhaps some day in the distant future, the wildly colorful
variety of life forms sheltered by the dozens of corals may themselves
be uplifted and exposed to erosion’s power of artistry! This will be
just one more spectacular feature in an ancient continent.
Stay tuned for the final installment of our travels to the Outback and our take aways from Earth Science Down Under.