introduction | balancing water and salt

A change of climate—one reason

Tropical rainforest palms
still living in special
places in the desert.
Photo: T Reardon

A wet past

As the climate of Australia became drier it affected the plants and animals that lived there.

• Some groups of animals and plants died out. All we have are their fossils.
• Some groups of animals and plants evolved to live in the drier climate.
• Some animals and plants were restricted to the small patches of remaining rainforest.

About 10 million years ago the Australian plate collided with the Asian plate, pushing up the New Guinea mountains and changing the warm tropical current from north of Indonesia which flowed along the western Australian coast. In turn, this reduced the amount of moisture carried inland across Australia by the prevailing westerly winds. As rainfall decreased, grasslands and desert began to replace the lusher vegetation across much of Australia. This is one factor which led to rainforests being confined to their present locations.

One reason is that Australia is on the move. Look at where it has gone in 135 million years!