Fossils up to 75,000 years old can be dated with

Fossils up to 75,000 years old can be dated with Carbon-14.
 
Radio isotopes can be used for the age determination of the fossils. Carbon-14 is a common isotope which is used for that purpose. But the half- life of the Carbon-14 is relatively small as 5730 years. That means the amount of Carbon-14 will be half after every 5730 years. Hence, decay is very fast. So Carbon-14 cannot be used forage determination which is more than 75000 years due to the low accuracy.

He should put sand around the spill in order to contain it so that it won't spread

Reproduction i think