Linda Hamilton, age 10,of Atlanta, Ga., for her question:
IS THE EARTH REALLY ONLY 6,000 YEARS OLD?
About a century ago, certain experts announced that our wondrous world is a little older than 6,000 years. This estimate was merely a guess, based on past dates of recorded human history. We now know that it was a very poor guess indeed. There are reasons why we cannot pinpoint the birth of the earth ¬but there is plenty of evidence to prove that it is at least 4 billion years old.
It seems we are a little sloppy about certain words we use to measure periods of time. For example, our days may mean 12 or 24 hours. The horse and buggy days lasted for centuries and the days of the dinosaurs lasted more than a million years. Obviously we need more precise terms to measure the history of the ancient earth.
Geologists divide the long story into five major chapters called eras. The evidence that tells the story is in the rocky Formations of the earth's outer crust. As life progressed, the earth kept a sort of diary and fossilized specimens were preserved among the rocky pages.
The evidence proves that a major era lasted hundreds of millions of years. It is divided into several shorter paragraphs called periods, each lasting tens of millions of years. The divisions between eras and periods are based on major natural changes that occurred in the earth's history. Our estimates of the earth's total age got longer and longer as experts probed deeper and deeper into the dim distant past.
We live in the Cenozoic Era, which began when the dinosaurs departed merely 60 million years ago. The dinosaurs thrived through the Mesozoic Era, which began about 220 million years ago. This followed the Paleozoic Era, which dates back 600 million years. The Archaeozoic Era began about 3 billion years ago. The records of the first chapter, the Azoic Era, are blurred with time. But they indicate that the long story began some 4.5 billion years ago.
Nobody knows the exact age of the earth and most likely we never will know. But we can be sure that it is much older than 6,000 years. Its true age is closer to 5 billion years.