Complex sentence: Pollen fossil sampling from the silt that had settled to the bottom of those craters since their formation confirmed Aboriginal myth-tellers advice that at the time eucalypt forests dominated rather than the current wet tropical rain forests.
Split into simpler sentences: Pollen fossil sampling from the silt which had settled to the bottom of the craters since their formation confirmed Aboriginal myth-tellers' story. When the craters were formed, eucalyptus forests dominated rather than the current wet tropical rain forests.