Fossil Sea-Shells

Date: 1890
Owner: D. Appleton and Company
Source Type: Images


Darwin collected these fossils in 1834 while exploring the Andes Mountains of Chile for six weeks with two local guides. He was fascinated by the fauna that lived at such high altitudes, such as pumas, condors, and a 2000 foot cloud of locusts, but his most remarkable discoveries in the mountains were geological. Darwin questioned where these (and all) mountains came from and when they were formed, and he suspected (correctly) that these fossils held a clue to the answer.

He found shells like these at 12,000 feet above sea level, causing him to ponder how marine fossils existed so far inland and at such high altitudes. Darwin concluded that the southern region of South America must have been submersed in the ocean before being elevated above water. Deposits of ocean sediment in the valleys between the Andean peaks inspired the idea that, for a time, the apexes of the range were individual islands in the southern ocean, and only the continuous process of elevation brought them to their contemporary grandeur. Plate tectonics, the modern theory that explains how mountain ranges are raised by the collision and subduction of huge pieces of the lithosphere, did not fully develop until the early 1960s, but the observations of nineteenth century naturalists like Darwin brought such fundamental questions to the fore.

CITATION: Darwin, Charles. Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage Round the World of H.M.S. 'Beagle' Under the Command of Captain Fitz Roy. R.N. New York: D. Appleton and Company, 1890.