Where did Darwin collects fossilized sea shells in mountain top caves?

Darwin collected fossilized sea shells in mountain top caves during his voyage on the HMS Beagle in the Andes Mountains of South America, particularly in places like Patagonia. He observed these fossils at high elevations, which contributed to his understanding of geological processes and the theory of evolution. The presence of marine fossils in such locations indicated that these areas had once been underwater, supporting the idea of gradual geological change over time.