Geological Observations on South America - Being the Third Part of the Geology of the Voyage of the Beagle, under the Command of Capt. Fitzroy,

This was the third and last instalment of Darwin's account of the geological research he did during his five-year voyage on the Beagle. First published in 1846, it focuses on the geological history of South America. It includes detailed maps of South America and sketches of the terrain discussed.