Earthwatch Australia Teach Live

A view from the mountain side to the sea.

This region of the North queensland coast has been formed by a number of major geological events over the last 400 million years.

At about 420 million years ago, the coast was connected to other ancient landmasses but as this part of the coast separated a trough formed like a large bowl at the foot of the then existing mountains. Sediment formed by erosion filled this trough, washed down from these mountains and eventually formed layers of rock at the base of the mountains.

Some time later around 360 million years ago these layers were squeezed – like putting 4 different coloured sponges on top of one another and then pushing the ends toward each other. This formed hills – and the heat generated changed the rocks from sedimentary to metamorphic rocks. These folds formed a new mountain range – much wider that we see today.

Later still, around 100 million years ago, molten lava domes formed under these hills. Some forced their way upwards and became volcanoes – one estimate is that there were up to 380 active vents in this region. Other magma chambers simply cooled under the surface forming huge granite balls. These granites have been pushed up over time to the surface, large enough to form mountains of their own and much of the country side is littered with broken boulders which are remnants the upper parts of these granites.

From 65 million years ago to now, the sea levels have risen and fallen a number of times which has helped erode much of these original mountains leaving what we see today – a narrow line of mountains formed by both volcanism and the folding and pressure of the earth.

Task 1 - Draw a time line of the geological events that have occurred in this region... research and insert when dinosaurs rose and then disappeared.

Task 2 – Research one of the following:

How are magma chambers are formed?

How do volcanoes work?

What is erosion and what causes it?

What is the difference between Granite and Basalt?

How are volcanic lakes formed?

Find a volcanic lake in the Cairns regions; what is it used for today?

- Present your findings to the class.