Geology of the area of Bahía Blanca, Darwin's view and the present knowledge: a story of 10 million years

Abstract

Theaim of this paper is to give an updated outlook of the scenery described by Charles Darwin when he visited Bahía Blanca and surrounding areas, following the itinerary during hisvoyage on board HMS Beagle. Such an outlook is a state of the art of the current understanding of the Late Miocene-Holocene history in the southwestern Pampas (Argentina). Multidisciplinary results were integrated in a chrono sequence chart synthesizing the suggested space-time correlation of the recognized events. Some of the studied localities covering the whole time interval represented in the area were arranged in this chart in a hypothetical E-W line crossing the Río Sauce Grande basin and the surrounding highlands. This line is also approximately the one followed in partby Darwin when riding from Bahía Blanca to Tapalqué (Tapalguen) as he crossed the region toward the Río Sauce. Paleoenviromental and paleoclimatic inferences for the last 10 m.y. are also given. Paleontological studies included vertebrates, ostracods and palynomorphs. Many of the resultsof these investigations are the answers to Darwin's question when he first visitedthe area.