As discussed earlier, this work by Charles Darwin was a journal of his keen observations of various localities around the world.  His notes during this voyage show his changing view on mutability of species.  In it we can read the first inklings of his theories on evolution and common descent.

Chapter 14 of this work focused on Central Chile.

A brilliant interactive study of the voyage can be enjoyed here.

http://www.aboutdarwin.com/voyage/voyage01.html

Chapter XIV focusing on central Chile may be read here:

http://www.bartleby.com/29/14.html#21

Or listened to here: