An 8500-Year Record of Lacustrine Activity and Changes in Archaeological Settlement Patterns in the Magdalena Lake Basin, Jalisco, Mexico

Abstract

The Magdalena Lake Basin of Jalisco, Mexico, has a rich cultural history from the Early Formative to Protohistoric Periods (1500 BCE–1600 CE). We investigated the relationship between climate chronologies, lake-level variations, and cultural changes before European contact. Chronostratigraphic reconstructions identified lake-forming periods reflecting regional and local paleoclimate sequences and coincide with variations in site location, numbers, and size, derived from our regional archaeological survey. Populations increase during high lake levels and decrease during low lake levels. An Early Archaic lake (~6800–5060 BCE) gives way to lowered lake levels in the Middle (~4980–3790 BCE) to Late Archaic (~1800 BCE). Pollen evidence for agricultural clearing appears at the end of this low period. The highest lake level, 1367 masl, occurred during the Middle Formative, followed by Late Formative/Classic lakes between 1361 and 1364 masl. The Epiclassic Period (~600–1000 CE) experienced low lake levels, coincident with a pan-Mesoamerican drought. Dated tephra layers (500–600 CE) several centimeters thick significantly impacted lake ecology and human populations. Tephra age and geochemical properties do not match the primary candidate at the nearby Ceboruco Volcano in the 10th century CE nor any other known eruption during this time period.