The Sierra Nevada range reached its present height 50 million years ago — 30 million years earlier than geologists once believed, according to a new study.
The research adds to a growing body of evidence that the Sierra Nevada is far older than once thought and has implications for the evolution of the plants and animals in the West.
The study, by scientists at Yale University and the University of California Museum of Paleontology, used 50 million-year-old chemical traces left by microbes and rain droplets that fell onto ancient leaves to calculate the new height estimate for the mountains at that time. The western United States would have been filled with lush forests of vines and magnolias.
“This is a time period where there would have been crocodiles in Wyoming,” said Michael Hren, lead author and a University of Michigan postdoctoral fellow who did the research while at Yale.
Putting together data to create a coherent picture of the past is what drew him to the work, Hren said. “It’s amazing to break open a rock and look at these amazingly preserved leaves that can tell you a story from 50 million years ago,” he said.