So by extracting a cylindrical core sample containing layers that go way back, they can build a model of the climate of the past.
[Image courtesy of Accu ] Finally, pollen is good for something besides making you sneeze.
But those rocks also carry less obvious information—their magnetic signatures.
Ice sheets are laid down in layers, and the layer corresponding to each year is a little different.
The important thing for climate researchers is that the oxygen isotopes present in a layer can help show what the temperature was that year.
It also led him to the conclusion that it was created in 1944, meaning it was created during the Manhattan Project, making it one of the world's oldest-known samples of enriched plutonium.
[Image courtesy of .] A pile of skeletons probably wouldn't tell us much more than the obvious.
Moa, the giant flightless birds of New Zealand, may have been extinct for at least 500 years, but their dung is surprisingly resilient.
On cave floors and buried in shelters, researchers found dung from the moa, with some of the samples being 15 cm (nearly six inches) in length.
Medieval manuscripts have a lot more to say than simply the words on their pages; often they're written on parchment made from animal skins, and organic material keeps its secrets for a long time.
Literary historian Timothy Stinson developed a way to extract the DNA from parchment itself, and if you can tell what animal a parchment was derived from, you might be able to tell more about what time and place the document originated.
It's wasn't so long ago that megafauna ruled the American continent.
Sloths and wooly mammoths pushed their weight around; horses and camels had their day.
At the time rocks form, however, their magnetic materials acquire the particular orientation of the planet's magnetism at the time, giving geologists a window into the Earth's magnetic past.