Varve, paleomagnetic, and C-14 chronologies for late pleistocene events inNew Hampshire and Vermont (USA)

Citation
Jc. Ridge et al., Varve, paleomagnetic, and C-14 chronologies for late pleistocene events inNew Hampshire and Vermont (USA), GEOGR PHYS, 53(1), 1999, pp. 79-107
Citations number
124
Categorie Soggetti
Earth Sciences
Journal title
GEOGRAPHIE PHYSIQUE ET QUATERNAIRE
ISSN journal
07057199 → ACNP
Volume
53
Issue
1
Year of publication
1999
Pages
79 - 107
Database
ISI
SICI code
0705-7199(1999)53:1<79:VPACCF>2.0.ZU;2-Y
Abstract
A deglacial chronology for northern New England has been formulated using a n atmospheric C-14 calibration of the New England Varve Chronology and pale omagnetic records. This C-14 chronology is based on C-14 ages from macrofos sils of non-aquatic plants and is about 1500 yr younger than existing chron ologies that are based primarily on C-14 ages of bulk organic samples. The lower and upper Connecticut Valley varve sequences of Ernst Antevs (NE varv es 2701-6352 and 6601-8500) overlap (lower 6012 = upper6601) based on their crudely matching varve records and their similar paleomagnetic records. Th ree 14C ages at Canoe Brook, Vermont (NE varve 6150 = 12.3 C-14 ka) calibr ate the lower Connecticut Valley sequence. New AMS and conventional C-14 ag es on woody twigs from Newbury, Vermont calibrate the upper sequence from 1 1.6-10.4 C-14 ka (NE varves 7440-8660) and are consistent with the overlapp ing varve and paleomagnetic records, and the Canoe Brook C-14 ages. Deglaci ation of the Connecticut Valley in southern Vermont began at 12.6 C-14 ka ( 15.2 cal ka) and the Littleton-Bethlehem Readvance in northern New Hampshir e and Vermont reached its maximum at 11.9-11.8 C-14 ka(14.0-13.9 cal ka) fo llowed by recession of ice into Quebec at about 11.5 C-14 ka(13.4 calka). A lake persisted in the upper Connecticut Valley until at least 10.4(14)C ka (12.3 cat ka) and may have been seen by the first humans in the area.