Ice excavated from deep under the surface of Antarctica has just yielded humanity's oldest directly dated samples of glacial ice and air ever found. From beneath hundreds of meters of glacial ice that gradually accumulated over eons at Allan Hills , a team of scientists led by glaciologist Sarah Shackleton of the Woods Hole Oceanographic Institute has retrieved samples that have been buried for some 6 million years. "Ice cores are like time machines that let scientists take a look at what our