Oligocene, Epoch. A division of geologic time that began about 37,000,000 years ago and lasted 14,000,000 years. The Oligocene is the third and latest division of the Paleogene Period. Most of the rock formed during the Oligocene is sedimentary-During this time some mountain building occurred in the northwestern United States. Petroleum and natural gas are found in commercial quantities in rocks of the Oligocene Epoch.
We've been scribbling our thoughts down on stone and paper for a while now. But the job of assembling a history for all of humanity gets a lot harder once those written records disappear. Luckily, archaeologists are happy to tackle the job.
Every time a new fossil is found, one of the first things scientists determine is how old that fossil really is. But how do they determine it, and how can they be completely accurate?