Ancient rocks suggest that ice entirely covered our planet on at least two occasions. This theory may help explain the rise of complex life that followed.
After 100 years as a national park and eons as a geological wonder, the American icon continues to reveal layers of its past and of the landscape ahead
Five new things we’re learning about the extinct animals and their ancient kin
Geologists explore the rise of the Andes, whose high-altitude peaks and plateau alter global climate.