3000 years of environmental change at Zaca Lake, California, USA.

摘要

This study uses pollen and sediments to generate a 3000 year record of vegetation and climate along the southern California coast, and discusses implications for regional anthropologic models of Native American cultural evolution. High Salix percentages and high pollen concentration from 500 to 250 cal yr BP represents the wettest period of the record. There is evidence for 3 warm periods between 1350 and 650 cal yr BP identified in the record by the presence of Pediastrum boryanum var. boryanum. A multi-centennial drought between 2700 and 2000 cal yr BP is identified, corroborating evidence from across the Great Basin. Corresponding wetter conditions in the northwest indicate that the modern ENSO precipitation dipole likely persisted during this drought. Today this dipole is associated with La Nina conditions. This period corresponds with key changes in Chumash culture, and a new model of the impacts of climate on Chumash cultural evolution is suggested.