They have the mystery of ferns that disappeared a million years ago into the coal of the carboniferous era.

During the carboniferous times the poles were as warm as the tropics and when the Ice Age came on it was very chilly everywhere.

The Dawson, Comet, Mackenzie, Isaacs, and Bowen Rivers drain this carboniferous area; and numerous outcrops of coal have been observed on these streams.

When they re-emerge, in what is called the Lower Carboniferous period, they do, indeed, live up to their potential.

"By the Carboniferous, life had become so well established on land that there were thriving biomes all over the world," says Dooley.

Their numbers began to decline throughout the Silurian, Devonian and Carboniferous periods, before completely petering out by the end of the Permian for reasons unknown.