THE GEOLOGICAL EVOLUTION OF THE ANDES AND AMAZON: CONSTRAINING PHYLOGENETIC ANALYSES
The main difficulty faced by geologists undertaking paleogeographic reconstruction of the region is that few outcrops exist across all of TSA. Most of the geologic history is buried deep beneath the modern forest. However, it is also true that geologists have made unfounded assumptions in interpreting the geologic and geochemical data from scattered outcrops and drill cores. We will briefly review and provide our own evaluation of prior interpretations of key elements of the history of TSA, such as the Cenozoic history of the uplift of the Andes, marine incursions in the western Amazon, the so-called Pebas mega-lake or mega-wetland, the role of “tectonic arches” in affecting Cenozoic drainages, the eastward flow of the Amazon to the Atlantic, and Quaternary or earlier climate variation. The best future path to reconcile these issues and to accurately constrain the nature and timing of vicariant events is to obtain much more substantial geologic data, and the only effective way to do that is by deep drilling across the entire Amazon.