Rodents tell a geologic tale
By Sid Perkins
From Ottawa, at a meeting of the Society of Vertebrate Paleontology
The discovery of previously unknown rodent species that lived in Chile millions of years ago suggests that mountains in the southern Andes first rose to significant heights at least 18 million years ago.
By measuring the proportions of radioactive isotopes in ash deposits, scientists can estimate the date but not the height of a particular volcanic eruption. Therefore, geologists haven’t been able to determine when the southernmost portions of South America’s Andes, as a whole, rose to their current heights, says Jill Wertheim, a paleontologist at the University of California, Santa Barbara. Fossils could provide the answer.