Summary: Quaternary Science Reviews 26 (2007) 1713­1724
Orbital- and millennial-scale vegetation and climate changes of the past
225 ka from Bear Lake, Utah­Idaho (USA)
Gonzalo Jime´ nez-Morenoa,b,c,Ã, R. Scott Andersona
, Peter J. Fawcettb
a
Center for Environmental Sciences and Education, and Quaternary Sciences Program, Northern Arizona University, Flagstaff, AZ 86011, USA
b
Department of Earth and Planetary Sciences, Northrop Hall, University of New Mexico, Albuquerque, NM 87131, USA
c
Departamento de Estratigrafi´a y Paleontologi´a, Universidad de Granada, Fuente Nueva s/n, 18002, Granada, Spain
Received 8 November 2006; received in revised form 4 March 2007; accepted 7 May 2007
Abstract
Continuous high-resolution pollen data for the past 225 ka from sediments in Bear Lake, Utah­Idaho reflect changes in vegetation and
climate that correlate well with variations in summer insolation and global ice-volume during MIS 1 through 7. Spectral analysis of the
pollen data identified peaks at 21­22 and 100 ka corresponding to periodicities in Earth's precession and eccentricity orbital cycles.
Suborbital climatic fluctuations recorded in the pollen data, denoted by 6 and 5 ka cyclicities, are similar to Greenland atmospheric
temperatures and North Atlantic ice-rafting Heinrich events. Our results show that millennial-scale climate variability is also evident
during MIS 5, 6 and 7, including the occurrence of Heinrich-like events in MIS 6, showing the long-term feature of such climate
variability. This study provides clear evidence of a highly interconnected ocean­atmosphere system during the last two glacial/interglacial

Source: Anderson, R. Scott - Quaternary Sciences Program, Northern Arizona University
Jiménez-Moreno, Gonzalo - Departamento de Estratigrafía y Paleontología, Universidad de Granada

Collections: Environmental Sciences and Ecology; Geosciences