Early holocene glaciation on Mount Baker: Washington State, USA

The relation between radiocarbon-dated tephras and glacial moraines on the south Bank of Mount Baker, Washington, records evidence of an early Holocen e glacier advance. Scoria that erupted from a local cinder cone 8420 +/- 70 C-14 yr BP (9450 +/- 100 cal yr) occurs immediately in front of, but not o n, a complex of moraines overlain by Mazama ash. Radiocarbon ages of 7670 /- 130 C-14 yr BP (8415 +/- 110 cal yr) and 7045 +/- 65 C-14 yr BP (7890 +/ - 90 cal yr) were obtained from charred wood below the Mazama ash and above till of the moraines, bracketing the age of the glacial advance between si milar to 7700 and 8400 (14)Cyr BP (similar to 8400 and 9450 cal yr). Well-p reserved Little Ice Age moraines occur proximal to the maximum Holocene pos itions. Assuming that precipitation regimes were similar, depression of for mer equilibrium line altitudes suggests that climate during the early Holoc ene event was at most similar to 2 degrees C cooler than present, and simil ar to 0.5 degrees C cooler than the Little Ice Age. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.