Tomas Alarcon trotted his horse up to ride beside mine and pointed to the vertical layer cake of limestone and shale that rose above the ugly scar of a mining road across the valley.

“I climbed those cliffs when I was a child,” said my Chilean guide. “And you know what? There are millions and millions of seashell fossils in the rock. Here, at nearly five thousand meters!”

We rode in silence for a minute, pondering the massive tectonic forces that could lift what was once the bed of the Pacific Ocean more than 16,000 feet above sea level and create the cut-glass peaks of the Andes mountains…. Full Story