Data consists of summer temperature reconstruction based on laminae thickness
in sediments from Donard Lake, Baffin Island, Canada.
ABSTRACT (from the online documentation):
Clastic varved sediments from Donard Lake, in the Cape Dyer region of Baffin
Island, provide a 1250 yr record of decadal-to-centennial scale climate
variability. Donard Lake experiences strong seasonal fluctuations in ... runoff
and sediment fluxes due to the summer melting of the Caribou Glacier, which
presently dominates its catchment. The seasonal variation in sediment supply
results in the annual deposition of laminae couplets. A radiocarbon date
measured on moss fragments, with a calibrated age of 860 +/-80 yrs before
present (BP), is in close agreement with the age based on paired-layer counts.
Together with the fabric of the laminae determined from microscope analysis,
the age agreement demonstrates that the laminae couplets are annually
deposited varves. Comparisons of varve thickness and average summer
temperature from nearby Cape Dyer show a significant positive correlation (r=
0.57 for annual records, r = 0.82 for 3-yr averages), indicating that varve
thickness reflects changes in average summer temperature. Varve thickness was
used to reconstruct average summer temperatures for the past 1250 yrs, and
shows abrupt shifts and large amplitude decadal-to-centennial scale
variability throughout the record. The most prominent feature of the record is
a period of elevated summer temperatures from 1200-1375 AD, followed by
cooler conditions from 1375-1820 AD, coincident with the Little Ice Age.