A Geological Tour of Australia Quiz

Answer: Lichen

Granite is a coarse grained igneous rock. It is composed of quartz and feldspar and, based on the proportion, the colour ranges from white to gray or pink.

The Bay of Fires is located on the northeastern coast of Tasmania. The granite rocks found here are a stunning orange colour which provides a fiery contrast to the white sand of the beaches and the blue skies. One could easily mistake the bay having being so named for the colour of the rocks. However, Captain Tobias Furneaux actually named it in 1773 for the fires of the Aboriginal people which dotted the bay.

The colour of the granite rocks here is due to the presence of lichen. Lichens are formed by a combination of both algae and fungus and come in many different colours. The rocks at the Bay of Fires get their colour from the lichens belonging to the Hymeneliaceae family.

Answer: Stack

The Twelve Apostles are a group of limestone stacks. Collectively named the Twelve Apostles in reference to the Apostles of Jesus, there were originally only eight in the immediate vicinity. With the collapse of one in 2005, seven remain now.

Stacks are a type of landform formed due to erosion by both wind and waves along the coast. Since the rocks are made of limestone, they are soft and more easily eroded. The region was originally in the form of limestone cliffs. With continuous erosion, cracks formed leading to the creation of a cave. Eventually the entire lower portion gives way, leaving an arch. When the top portion collapses, stacks are left standing.

Answer: Yes

From an archaeological point of view, the Mungo National Park is one of the most important sites within Australia. Lake Mungo, an ancient dry lake inside this park, is the location where the oldest human remains on the continent were discovered. The remains of the Mungo Man date to almost 30,000 years ago making this one of the oldest human remains outside of Africa.

The Walls of China are crescent shaped dunes composed of sand and clay. They have been named after the Chinese workers engaged to construct a shearing shed at a nearby location.

The geology behind the formation of these ancient sand dunes is incredibly complex and has evolved over millions of years. To put it simply, the region was once covered by glaciers and ice landforms during the ice age. As the ice age retreated, lakes formed in this area. Large sand dunes formed on the edges of the lakes. With the climate of the region later moving to a drier and hotter environment, the lakes began to dry out. The clay that was at the bed of the lakes began to be deposited on the dunes. The action of the wind in this barren landscape caused the erosion of the dunes in the shape of a lunette - a crescent shaped dune.

Answer: Cave

The Sunken Garden is found in the Umpherston Sinkhole in Mount Gambier, South Australia. The region where this landmark is located is known as the Limestone Coast, due to the rich natural limestone deposits found here. As limestone dissolves easily in acid, a combination of rain and ground water caused the rocks to erode. Eventually this formed a cave. When the top of the cave collapsed due to no support from the underlying layers, a sinkhole was formed.

The sinkhole was named after James Umpherston who initiated the creation of the gardens in 1884. The top of the cave was composed of good quality soil. When it collapsed, it formed the base and was found suitable for growing plants. Created as a series of terraces, there are multiple viewing platforms and seating areas within the garden.

Answer: Weathering

The Pinnacles are found in the Nambung National Park in Western Australia. They consist of multiple limestone pillars rising from the ground. The process of their formation is interesting. Millions of years ago the area was bounded by sea. This is attested to by the presence of crushed seashells within the limestone pillars. Over a period of time the seashells weathered to form sands rich in limestone.

These solidified to form limestone rocks. When the lighter sand particles were eventually weathered, as the region turned from an ancient seashore to the present desert, what was left was the hard pillars of limestone.

Answer: Sedimentary

Fossils are most commonly found in sedimentary rocks. The process of formation of sedimentary rocks, where layers are deposited over a period of time, makes them most conducive to hold and preserve fossils. Stromatolites are formed by layer upon layer of cyanobacteria being deposited and eventually hardening to form a rock. The word stromatolite itself comes from the Greeks words for layer ('stroma') and rock ('lithos').

Stromatolites are the oldest fossils in the world. These are the earliest form of bacteria which were able to produce oxygen through photosynthesis. At one time they were the most dominant life form on the earth. However, the process of giving out oxygen led to the formation of other life forms and the eventual change in the climate and geology led stromatolites to die out. These were considered an extinct life form till they were rediscovered in the last century earning them the title of "living fossils".

Hamelin Pool in the Shark Bay Heritage Area contains the largest concentration of stromatolites in the world. One of the reasons for this is that the pool has a hypersaline environment with a salinity almost twice that of sea water, allowing these bacteria to thrive in it. As can be expected, these stromatolites are of utmost interest to geologists as they help to better understand how the earth evolved. The stromatolite fossils found here are also the oldest in the world dating back to 3.5 billion years!

Answer: Beehive

The Bungle Bungles are around 350 million years old. The region was first a river bed where sediment was deposited over a period of time. Geological faults caused the sandstone layers to be pushed up and compressed to form rocks. This was followed by wind and rain erosion which led to their unique beehive shape.

The rocks have bands of alternating black and orange colour. These coloured bands are due to the presence of different minerals within the sandstone layers. The orange colour is a result of iron and manganese deposits which have weathered to stain the rocks in this hue.

The dark grey bands are due to the presence of a particular algal growth. When rain water falls on these bands, the algae absorb the moisture and the band appears black.

Answer: Yes

The Horizontal Falls are a truly unique natural feature. As given away by the name, they are often described as a type of horizontal waterfall. However, they are not actually waterfalls. The name was coined by the well known British naturalist, David Attenborough, who has called them "one of the greatest wonders of the natural world".

There are only two such geographical landforms in the world and both are found in Talbot Bay in the Kimberley region of Western Australia. Given that this is such a rare phenomenon, it is hard to describe the action in words. The waterfall like effect is caused by large amounts of water rushing through the narrow gorges of the McLarty Range. Narrow channels through the range cause the tidal water to gush through the gaps in the gorges causing rapids. This area has some of the largest tides on the planet. When the water is in flow, it appears like a sleeping waterfall as the water rushes through the gorges from one level to the other. As these are fuelled by the tides, the waters also change their direction of flow when the tide changes.

Answer: Lava tubes

Undara is famous for its lava tubes. Millions of years ago, this region was a shield volcano. Lava frequently erupted and flowed out of this volcano. At one point, the river of lava was enclosed within a valley and the top part formed a crust like cover and solidified creating a tunnel for the lava to flow through. Ultimately when the lava drained out, a lava tube formation was left behind.

This is one of the longest lava tube formations in the world. The Undara Volcano is now extinct.

Answer: Sandstone

Uluru is also known as Ayers Rock and is found within the Northern Territory of Australia. Composed of sandstone, this rock formation is sometimes likened to an iceberg. Despite standing at a height of 348 meters above ground, the majority of it is underground. Since it is surrounded by flat land in all directions for miles, while looking at it, one is unable to really appreciate its size. For comparison, Uluru, above the ground, is 24 meters taller than the Eiffel Tower, at its highest point. That is not all.

The rock formation underground is estimated to be 2.5 kilometers. Uluru is believed to have been formed around 500 million years ago. This is around the same time that Australia separated out into a continent. The sediments that eventually formed Uluru were deposited when the area was covered by a shallow sea.

The sea receded and the natural process of orogeny pushed the rocks above folding them under tight pressure to create a single landform.