January 7 is Old Rock Day. The unofficial holiday encourages people to acknowledge, celebrate, and learn more about old rocks and fossils.
A rock is a solid mass made of minerals or mineral-like substances. Used for a variety of purposes throughout the history of humankind - as tools, musical instruments, weapons and for mining - rocks form the outermost layer of Earth.
A Peek Into Earth's History
While natural processes - volcanic eruptions and erosion - continually help create rocks on Earth, old rocks are especially important to those who study the Earth and its history. Old rocks hold many answers to the mysteries of Earth's formation - they can tell scientists about natural events that played a role in the formation of the rocks and the effects that event had on other life forms in the area.
Old rocks can also sometimes hold fossils - the preserved remains of animals, plants and other organisms. These fossils can help scientists find out the kind of flora and fauna that existed in the past and what may have caused them to evolve or go extinct.
Finding the Age of Old Rocks
Geologists date old rocks using a technique called radiometric dating or radioactive dating. The process involves looking at the decay of radioactive elements available in rocks. The oldest rock of terrestrial origin to be dated using this method is a zircon found in the Jack Hills of Australia. Scientists estimate that the rock could be as old as 4.4 billion years.
How to Celebrate?
Learn more about the types of old rocks.
Pick up a book about fossils and learn how fossils tell us more about the Earth’s past or visit your local natural history museum.
Take a walk in the park and collect interestingly shaped rocks.
Buy your loved ones some pretty looking rocks. And by rocks, we mean jewels. After all, diamonds are old rocks.