Evolution

Geological / environmental event

The Elder Gods wait patiently for millions of years for life to be born from their focussed magics, arising deep within the lava-flows of the planet. The new life emerges as the world cools.
  The great lava flows leave vast tracks of hollowed out earth and underground waterways where the ecosystems are born - many feeding directly from the magic that flows through the veins of the earth.
  Life emerges onto the surface and explodes in diversity beneath the light of the sun.
  This is the sign the Elder Gods are waiting for, The ripening of the World.