sentences: fossil fuels / fossils forming occurs over a period of 300000000 years which is considered a very long time to a human
docs: fossil is remains. period is geological_time. petroleum is fossil_fuel. gestation_period_for_humans is 9_months_from_conception. fossil_fuel_generation is geologic_process. geological_period is geological_time_period. geological_era is geological_time_period. geological_age is geological_time_period. years has 366_days