Reading Earth's magnetic history

In order to date environmental events from Earth's history — such as meteorite impacts or climate change — geologists have long studied variations in slow-growing seafloor sedimentary rocks called ferromanganese crusts that build up in layers over the eons. The layers can be dated by various means, such as by analyzing radioactive isotopes, but those methods don't provide accurate dating on small scales: a millimeter of rock, for example, can include information that spans as much as hundreds of thousands of years.

Read the whole article on Physorg

More from Physorg