P-202604 comments

10Be and 26Al production rate calibration comments (14C: see below)
expage.github.io

Baboon Lake, Sierra Nevada, W USA
Cosmogenic data from Borchers et al. (2016), Marcott et al. (2019), and Moore and Granger (2019).
Erosion rate set to 0 mm/ka for all samples.
Sampling year for Borchers et al. (2016) and Moore and Granger (2019) samples based on sample names.
Calibration age based on Clark and Gillespie (1997) 14C age of 11190 ± 70 BP. Calibration using the
IntCal20 curve yields an age of 13102 ± 75 cal BP. Plus 57/58/65 years for sampling year.
Calibration age uncertainty of 250 years assumed.
Three 10Be production rates are excluded (SNV-02, SNV-03, SNV-08) to fulfill the clustering
criterion.
Isostatic adjustment calibration data: ICE7G.

SP lava flow, Arizona, USA
Cosmogenic 10Be data from Fenton et al. (2019) and 26Al data from Fenton et al. (2022).
Calibration age of 72000 ± 2000 yr from Fenton et al. (2019) based on 40Ar/39Ar dating.
Isostatic adjustment calibration data: Gowan2021.

Lake Bonneville shoreline, W USA
Cosmogenic data from Lifton et al. (2015).
Calibration age based on 14C ages and U-series data (Lifton et al. 2015) with an IntCal09 age of
18300 ± 300 cal BP. Back-calculation with IntCal09 yields a 14C age of 15119 ± 279 yr BP, which,
calibrated with IntCal20, yields an age of 18427 ± 299 cal BP. Plus 55 years for sampling year.
Uncertainty kepts as 300 years.
Isostatic adjustment calibration data: ICE7G.

Cobblestone Hill spillway, NE USA
Cosmogenic data from Balco et al. (2009).
Sampling year based on sample names.
Calibration age based on IntCal04 calibration age range in Balco et al. (2009) of 13051-13316 cal
BP. Back-calculation with OxCal 4.4 yields a 14C age of 11299 ± 150 yr BP , which, when calibrated
with IntCal20 yields an age of 13200 ± 144 cal BP. Plus 56 years for sampling year.
Isostatic adjustment calibration data: ANU2017.

Leverett spillway, NE USA
Cosmogenic data from Balco et al. (2009).
Sampling year based on sample names.
Calibration age based on IntCal04 calibration age in Balco et al. (2009) of 15850 ± 300 cal BP.
Back-calculation with IntCal04 yields a 14C age of 13349 ± 183 yr BP , which, when calibrated with
IntCal20 yields an age of 16074 ± 273 cal BP. Plus 56 years for sampling year. Uncertainty is kept
from Balco et al. (2009) as 300 years.
Isostatic adjustment calibration data: ANU2017.

Littleton/Birch Hill moraine, NE USA
Cosmogenic data from Balco et al. (2009) and Borchers et al. (2016).
Erosion rate assumed to be 0.00007 cm/yr for all samples based on Balco et al. (2009).
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) IntCal09 age of 13900 ± 250 cal BP.
Back-calculation with IntCal09 yields a 14C age of 12005 ± 163 BP, which, when calibrated with
IntCal20 yields an age of 13928 ± 245 cal BP. Plus 56/57 years for sampling year. Uncertainty is
kept from Borchers et al. (2016) as 250 years.
Isostatic adjustment calibration data: ANU2017.

Clyde River delta, Baffin Island
Cosmogenic data from Balco et al. (2009) and Young et al. (2013).
Topographic shielding factors calculated from DEM based on Codilean (2006) and Li (2013).
10Be concentrations from Balco et al. (2009) converted to 07KNSTD standardization before calculation
of uncertainty-weighted mean concentrations.
Sampling year based on sample names.
Calibration age based on 3 min and 3 max 14C ages from Briner et al. (2007) calibrated with the
Marine20 calibration curve and a and ΔR = 130 year (Young et al. 2013) using the Bayesian approach
of Martin et al. (2015). This yields a calibration age of 8050 ± 248 cal BP. Plus 51/53 years for
sampling year. Uncertainty is kept from Balco et al. (2009) as 250 years.
Isostatic adjustment calibration data: ANU2017.

Tasiussaq moraine, W Greenland
Cosmogenic data from Briner et al. (2012) and Young et al. (2013).
Sampling year based on sample names.
Calibration age based on 4 min and 5 max 14C ages from Briner et al. (2012) calibrated with the
IntCal20 and Marine20 calibration curves using the Bayesian approach of Martin et al. (2015). This
yields a calibration age of 8064 ± 271 cal BP. Plus 58/59 years for sampling year. Uncertainty set
to 500 years to cover the wide spread between min and max ages.
Isostatic adjustment calibration data: ICE7G.

Marrait moraine, W Greenland
Cosmogenic data from Young et al. (2013).
Sampling year based on sample names.
Calibration age based on two min and two max 14C ages from Young et al. (2013) calibrated with the
IntCal20 calibration curve using the Bayesian approach of Martin et al. (2015). This yields a
calibration age of 9174 ± 61 cal BP. Plus 61 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Coire Fearchair YD deglaciation, NW Scotland
Cosmogenic data from Borchers et al. (2016).
Erosion rate set to 0 mm/ka for all samples.
Sampling year based on sample names.
Calibration age 11700 cal BP from Borchers et al. (2016) based on Greenland ice core chronology.
Plus 56 years for sampling year. Calibration age uncertainty set to 500 yr (300 yr in Borchers et
al. 2016) in light of conflict regarding Scotland YD deglaciation (see site Rannoch Moor below).
Isostatic adjustment calibration data: ICE7G.

Corrie nan Arr YD deglaciation, NW Scotland
Cosmogenic data from Borchers et al. (2016).
Erosion rate set to 0 mm/ka for all samples.
Sampling year based on sample names.
Calibration age 11700 cal BP from Borchers et al. (2016) based on Greenland ice core chronology.
Plus 52/56 years for sampling year. Calibration age uncertainty set to 500 yr (300 yr in Borchers et
al. 2016) in light of conflict regarding Scotland YD deglaciation (see site Rannoch Moor below).
Isostatic adjustment calibration data: ICE7G.

Maol Chean-dearg YD deglaciation, NW Scotland
Cosmogenic data from Borchers et al. (2016).
Erosion rate set to 0 mm/ka for all samples.
Sampling year based on sample names.
Calibration age 11700 cal BP from Borchers et al. (2016) based on Greenland ice core chronology.
Plus 56 years for sampling year. Calibration age uncertainty set to 500 yr (300 yr in Borchers et
al. 2016) in light of conflict regarding Scotland YD deglaciation (see site Rannoch Moor below).
Isostatic adjustment calibration data: ICE7G.

Rannoch Moor, Scotland
Cosmogenic data from Putnam et al. (2019) and Small and Fabel (2016).
Sampling year assumed to be 2014 for Small and Fabel (2016) samples.
Calibration age set to 11700 ± 500 yr (same as Scotland sites above) in light of conflicting views.
Plus 60/64 years for sampling year.
Conflicting views on deglaciation age:
Putnam et al. (2019) - midpoint age between bracketing 14C ages (IntCal 13): 12590 ± 140 cal BP.
Lowe et al. (2019) - radiocarbon ages and tephrochronology: deglaciation c. 11500 cal BP.
Isostatic adjustment calibration data: ICE7G.

Glen Roy glacier lake shorelines, Scotland
Cosmogenic data from Small and Fabel (2015).
Sampling year based on sample names.
Calibration age based on proposed tephra ages (Small and Fabel 2015) using the midpoint of 12013 ±
267 b2k and 11938 ± 275 b2k. The uncertainty is constructed to cover the uncertainties of both the
min and the max age. Plus 6 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Halsnøy moraine, W Norway
Cosmogenic data from Goehring et al. (2012).
Sampling year based on sample names.
Calibration age based on the age-depth modelling OxCal code for the Eplandmyr stratigraphy in the
supplementary data of Lohne et al. (2012), re-run using OxCal 4.4 and the IntCal20 curve, yielding a
deglaciation age (upper glacial silt boundary) of 11576 ± 101 cal BP. Plus 58 years for sampling
year.
Isostatic adjustment calibration data: PD2015.

Oldedalen rock avalanche, W Norway
Cosmogenic data from Goehring et al. (2012).
Sampling year based on sample names.
Calibration age based on one 14C age of 5220 ± 80 BP from outer wood (Nesje 2002: Beta-155582),
calibrated using the IntCal20 curve, yielding an age of 6010 ± 113 cal BP. Plus 58
years for sampling year.
One 10Be production rate is excluded (OL08-11) to fulfill the clustering criterion.
Isostatic adjustment calibration data: PD2015.

Grøtlandsura rock avalanche, N Norway
Cosmogenic data from Fenton et al. (2011).
Calibration age based on two 14C dates from marine shells in Fenton et al. (2011) yielding a
weighted mean 14C age of 9923.2 ± 17.7 BP. Calibration against the IntCal20 calibration curve yields
an age of 11313 ± 43 cal BP. Plus 56 years for sampling year. Uncertainty set to 800 years to
include 6-8% uncertainties for the shielding.
Isostatic adjustment calibration data: PD2015.

Russenes rock avalanche, N Norway
Cosmogenic data from Fenton et al. (2011).
Calibration age based on three 14C dates from marine shells in Fenton et al. (2011) yielding a
weighted mean 14C age of 9593.7 ± 33.5 BP. Calibration against the IntCal20 calibration curve yields
ing an age of 10937 ± 109 cal BP. Plus 56 years for sampling. Uncertainty set to 1000 years to
include 8-12% uncertainties for the shielding.
Isostatic adjustment calibration data: PD2015.

Billingen Baltic ice lake drainage, S Sweden
Cosmogenic data from Stroeven et al. (2015).
Sample elevations updated based on LiDAR 1 m elevation. Single 26Al measurement from Stroeven et al.
(2016).
Calibration age based on correlation of clay varve record and the δ18O NGRIP record: drainage event
age = 11620 cal BP. Plus 53 years for sampling year. A combined uncertainty of 300 years has been
assigned to the clay varve/ice core correlation and emergence history. Calibration carried out using
the isostatic adjustment for shielding/production under water (isostsubm), with the PD2015 (Påsse
and Daniels 2015) uplift history modified by a factor of 1.13 (isostsubmmod) to match the highest
shoreline at 122-136 m a.s.l. (interpolated by the Swedish Geological Survey) at the sample
locations and the time of deglaciation.
Isostatic adjustment calibration data: PD2015 modified by 1.13 (isostPmod).

Black Forest
Cosmogenic data from Hofmann et al. (2024).
Calibration age 15680 ± 420 cal BP from Hofmann et al. (2024) based on minimum age limiting
radiocarbon ages calibrated against the IntCal20 calibration curve yielding 95% ranges of 15600–
15210, 15480–15040, and 15680–15240 cal BP plus a luminescence date of 15.8 ± 1.7 ka. Plus 70 years
for sampling year.
Isostatic adjustment calibration data: ICE7G.

Chironico landslide, S Swiss Alps
Cosmogenic data from Claude et al. (2014).
Sample density assumed to be 2.65 g/cm3.
Sampling year assumed to be 2012.
Calibration age based on three 14C dates from wood fragments in Antognini and Volpers (2002)
yielding a weighted mean 14C age of 11502.9 ± 173.1 BP. Calibration against the IntCal20 calibration
curve yields an age of 13389 ± 166 cal BP. Plus 62 years for sampling year.
One 10Be production rate is excluded (Chi-10) to fulfill the clustering criterion.
Isostatic adjustment calibration data: ICE7G.

Lake Mahoma moraine, Rwenzori Mountains, Uganda
Cosmogenic data from Anderson et al. (2026). The 10Be concentrations are a bit lower than the
concentrations published in Jackson et al. (2019) but the Anderson et al. (2026) concentrations are
correct (based on email contact with Margaret Jackson).
An erosion rate of 1 mm/ka assumed based on Anderson et al. (2026) supplementary information stating
that two LGM (c. 20 ka) boulders in the Nyamugasani valley displayed quartz veins protruding 1-3 cm
above surrounding rock surface.
Calibration age based on two 14C dates presented in Anderson et al. (2026):
17600 ± 160 14C yr BP (OS-150232)
17700 ± 170 14C yr BP (OS-147844)
yielding a weighted mean 14C age of 17647 ± 71 BP. Calibration against a 50%:50% mixed calibration
curve of the IntCal20 and the SHCal20 calibration curves yields an age of 21293 ± 161 cal BP. Plus
62 years for sampling year. Uncertainty of 500 years assumed.
Isostatic adjustment calibration data: ICE7G.

Huancané II moraine, Quelccaya ice cap, Peru
Cosmogenic data from Kelly et al. (2015) and Phillips et al. (2016).
Latitude adjusted (-13.9657 to -13.9457) for sample Q-137 based on Figure 2 and Google Earth.
Erosion rate set to 5 mm/ka for all samples.
Sampling year for Kelly et al. (2015) samples assumed to be 2005 for KNSTD samples and 2008 for
07KNSTD samples.
Calibration age based on 7 min and 16 max 14C ages from Kelly et al. (2015) calibrated with a
50%:50% mixed calibration curve of the IntCal20 and the SHCal20 calibration curves and using the
Bayesian approach of Martin et al. (2015). This yields a calibration age of 12185 ± 552 cal BP. Plus
55/58 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Azanaques fan-delta, Bolivia, South America
Cosmogenic data from Martin et al. (2015).
Topographic shielding factors calculated from DEM based on Codilean (2006) and Li (2013).
Sampling year based on the ICE-D production rate database.
Calibration age based on Bayesian approach of Martin et al. (2015), with calibration against a
50%:50% mixed calibration curve of the IntCal20 and the SHCal20 calibration curves, yielding an age
of 16009 ± 587 cal BP. Plus 60 years for sampling year.
Three 10Be production rates are excluded (AZA-30, AZA-32, AZA-33) to fulfill the clustering
criterion.
Isostatic adjustment calibration data: ICE7G.

Herminita moraine, Lago Argentino, Patagonia
Cosmogenic data from Kaplan et al. (2011).
Sample density assumed to be 2.65 g/cm3.
Sampling year based on sample names.
Calibration age based on 14C age of 10350 ± 45 BP calibrated with the SHCal20 curve, yielding an age
of 12133 ± 158 cal BP. Plus 56/57 years for sampling year.
One 10Be production rate is excluded (HE-07-12) to fulfill the clustering criterion.
Isostatic adjustment calibration data: ICE7G.

Puerto Bandera moraine, Lago Argentino, Patagonia
Cosmogenic data from Kaplan et al. (2011).
Sample density assumed to be 2.65 g/cm3.
Sampling year based on sample names.
Calibration age based on 14C data from Strelin et al. (2011) calibrated with the SHCal20 calibration
curve and using the Bayesian approach of Martin et al. (2015) with two minimum ages and eight
maximum ages. This yields a calibration age of 12781 ± 171 cal BP. Plus 58 years for sampling year.
One 10Be production rate is excluded (EQ-08-04) to fulfill the clustering criterion.
Isostatic adjustment calibration data: ICE7G.

Macaulay valley debris flow, New Zealand
Cosmogenic data from Putnam et al. (2010).
Calibration age based on ten 14C dates from organic material buried below the debris flow in Putnam
et al. (2010) yielding a weighted mean 14C age of 8755.3 ± 51.6 BP. Calibration against the SHCal20
calibration curve yields an age of 9705 ± 112 cal BP. Plus 58 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Boundary Stream tarn moraine, inner recessional ridges, New Zealand
Cosmogenic data from Putnam et al. (2010).
Calibration age based on a basal 14C date (OS-42664) of 14800 ± 65 BP from Vandergoes et al. (2008),
calibrated against the SHCal20 calibration curve, yielding an age of 18078 ± 94 cal BP. Plus 58
years for sampling year. Uncertainty of 300 years assumed.
Isostatic adjustment calibration data: ICE7G.

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Comments to the data not included in the global average

Saddlebag Lake, W USA
Cosmogenic data from Nishiizumi et al. (1989).
Latitude, longitude, elevation, sample thickness, density, and shielding derived from Phillips et
al. (2016). 10Be standard assumed to be KNSTD.
26Al standard assumed to be KNSTD.
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) and Phillips et al. (2016) IntCal09
age of 15750 ± 500 cal BP. Back-calculation with OxCal 4.2 yields a 14C age of 13008.5 ± 236 BP,
which, calibrated with IntCal13, yields an age of 15558 ± 369 cal BP. Plus 36 years for sampling
year. Uncertainty is kept from Borchers et al. (2016) and Phillips et al. (2016) as 500 years.

Mount Starr, W USA
Cosmogenic data from Nishiizumi et al. (1989).
Latitude, longitude, elevation, sample thickness, density, and shielding derived from Phillips et
al. (2016).
10Be standard assumed to be KNSTD.
26Al standard assumed to be KNSTD.
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) and Phillips et al. (2016) IntCal09
age of 15750 ± 500 cal BP. Back-calculation with OxCal 4.2 yields a 14C age of 13008.5 ± 236 BP,
which, calibrated with IntCal13, yields an age of 15558 ± 369 cal BP. Plus 36 years for sampling
year. Uncertainty is kept from Borchers et al. (2016) and Phillips et al. (2016) as 500 years.

Twin Lake, W USA
Cosmogenic data from Nishiizumi et al. (1989).
Latitude, longitude, elevation, sample thickness, density, and shielding derived from Phillips et
al. (2016).
10Be standard assumed to be KNSTD.
26Al standard assumed to be KNSTD.
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) and Phillips et al. (2016) IntCal09
age of 15750 ± 500 cal BP. Back-calculation with OxCal 4.2 yields a 14C age of 13008.5 ± 236 BP,
which, calibrated with IntCal13, yields an age of 15558 ± 369 cal BP. Plus 36 years for sampling
year. Uncertainty is kept from Borchers et al. (2016) and Phillips et al. (2016) as 500 years.

June Lake, W USA
Cosmogenic data from Nishiizumi et al. (1989).
10Be standard assumed to be KNSTD.
26Al standard assumed to be KNSTD.
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) and Phillips et al. (2016) IntCal09
age of 15750 ± 500 cal BP. Back-calculation with OxCal 4.2 yields a 14C age of 13008.5 ± 236 BP,
which, calibrated with IntCal13, yields an age of 15558 ± 369 cal BP. Plus 36 years for sampling
year. Uncertainty is kept from Borchers et al. (2016) and Phillips et al. (2016) as 500 years.

Inner Titcomb Lakes Moraine, W USA
Cosmogenic data from Gosse et al. (1995), Balco et al. (2008), and Borchers et al. (2016).
Latitudes and longitudes based on map figures and Google Earth.
Shielding factor (including shielding by snow) derived from Borchers et al. (2016) and assumed for
sample 140-I to be the same as samples 138-I, 139-I, and 333-I.
10Be concentrations derived from Balco et al. (2008) supplementary dataset for 9 samples. For the
remaining sample (140-I) the 10Be concentration is derived by multiplying the published
concentrations in Gosse et al. (1995) by 0.972 based on the ratio between the Balco et al. (2008)
concentrations and the Gosse et al. (1995) concentrations.
10Be concentration uncertainties assumed to be 3% of the concentrations for all samples.
10Be standard assumed to be KNSTD.
26Al concentrations and uncertainties derived from Borchers et al. (2016).
26Al standard assumed to be KNSTD.
Sampling year based on sample names in Balco et al. (2008) supplementary dataset.
Calibration age and uncertainty based on Borchers et al. (2016) IntCal09 age of 12100 ± 700 cal yr
BP. Back-calculation with OxCal 4.2 yields a 14C age of 10429 ± 542 yr BP, which, calibrated with
IntCal13, yields an age of 12093 ± 694 cal yr BP. Plus 42/43 years for sampling year. Uncertainty is
kept from Borchers et al. (in press) as 700 years.

NC New Jersey, USA
Cosmogenic data from Larsen (1996).
Latitudes and longitudes based on map figures and Google Earth.
Topographic shielding factors based on dip angles derived from Balco et al. (2008) supplementary
dataset.
10Be concentrations calculated from isotope ratios and sample/carrier weight.
10Be standard based on direct information from Marc Caffee. 26Al standard assumed to be KNSTD.
Calibration age and uncertainty based on discussion in Clark et al. (1995) and Larsen (1996) with an
assumed 14C age of 19000 ± 1000 (IntCal13 age 23129 ± 1216 cal BP). Plus 44 years for sampling year.

Köfels landslide, W Austria
Cosmogenic data from Kubik et al. (1998) and Kubik and Ivy-Ochs (2004).
Latitudes and longitudes based on Figure 1 in Kubik et al. (1998), information in Kubik and Ivy-Ochs
(2004), and Google Earth.
Sample density assumed to be 2.65 g/cm3.
Shielding factors based on published values for topographic shielding and snow shielding from Balco
et al. (2008): 0.969.
10Be standard for all sampls assumed to be S555 based on Kubik and Ivy-Ochs (2004).
26Al standard assumed to be ZAL94.
Sampling year assumed to be 1996 for all samples.
Calibration age and uncertainty based on wiggle matching analysis of six radiocarbon dates from
Nicolussi et al. (2015) calibrated using the IntCal13 calibration curve to an age of 9513 ± 15 cal
BP. Plus 46 years for sampling year.

An Teallach cirque, Scotland
Cosmogenic data from Stone et al. (1998).
Latitudes and longitudes based on map figures and Google Earth.
Sample thickness back-calculated from thickness correction in Table 1 and 3, assuming a sample density of 2.65 g/cm3.
26Al standard assumed to be Z92-0222.
Sampling year assumed to be 1996.
Calibration age 11700 ± 300 cal BP from Borchers et al. (2016) based on Greenland ice core
chronology. Plus 46 years for sampling year.

Breque moraine, Cordillera Blanca, Peru
Cosmogenic data from Farber et al. (2005).
Sample thickness assumed to be 2.5 cm.
Sample density assumed to be 2.65 g/cm3.
Topographic shielding factors calculated from SRTM 90 m dem based on Codilean (2006) and Li (2013).
10Be standard derived from the ICE-D production rate calibration database
(http://calibration.ice-d.org/).
Sampling year assumed to be 1998 based on some sample names.
Calibration age and uncertainty based on radiocarbon data in Farber et al. (2005) calibrated with
OxCal 4.2 using the ShCal13 curve. Min age: 12826 ± 76 cal BP (14C age 10990 ± 60 BP). Max age: 
13093 ± 122 cal BP (14C age 11280 ± 110 BP). Calibration age: midpoint of the min and max ages.
Uncertainty covers both the min and the max ages. Plus 48 years for sampling year.

Holyoke Range, NE N America
Cosmogenic data from Balco et al. (2009).
Sampling year based on sample name.
Calibration age and uncertainty based on Balco et al. (2009) IntCal04 age of 16750 ± 320 cal BP.
Back-calculation with OxCal 4.2 yields a 14C age of 14025.5 ± 187 BP, which, when calibrated with
IntCal13 yields an age of 17022 ± 285 cal BP. Plus 56 years for sampling year. Uncertainty is kept
from Balco et al. (2016) as 320 years.

Asheulot River Valley, NE N America
Cosmogenic data from Balco et al. (2009).
Sampling year based on sample names.
Calibration age and uncertainty based on Balco et al. (2009) IntCal04 age of 15100 ± 300 cal BP.
Back-calculation with OxCal 4.2 yields a 14C age of 12810.5 ± 170 BP, which, when calibrated with
IntCal13 yields an age of 15261 ± 314 cal BP. Plus 56 years for sampling year. Uncertainty is kept
from Balco et al. (2016) as 320 years.

Perry Mountain moraine, NE N America
Cosmogenic data from Balco et al. (2009).
Sampling year based on sample names.
Calibration age and uncertainty based on Balco et al. (2009) IntCal04 age of 14590 ± 230 cal BP.
Back-calculation with OxCal 4.2 yields a 14C age of 12495 ± 98 BP, which, when calibrated with
IntCal13 yields an age of 14679 ± 247 cal BP. Plus 56 years for sampling year. Uncertainty is kept
from Balco et al. (2016) as 320 years.

Puget Lowland sites (Whidbey Island and San Juan Island), NW USA
Cosmogenic data from Borchers et al. (2016).
Sampling year based on sample names.
Calibration age and uncertainty based on Borchers et al. (2016) IntCal09 age of 15560 ± 500 cal BP.
Back-calculation with OxCal 4.2 yields a 14C age of 12893.5 ± 205.5 BP, which, calibrated with
IntCal13, yields an age of 15388 ± 348 cal BP. Plus 56 years for sampling year. Uncertainty is kept
from Borchers et al. (2016) as 500 years.

====================================================================================================
14C production rate data:

White Mountains
Data from Borchers et al. (2016) and Koester and Lifton (2023).
Calibration age from Koester and Lifton (2023): 50000 ± 500 yr.
Isostatic adjustment calibration data: Gowan2021.

Death Valley
Data from Borchers et al. (2016) and Koester and Lifton (2023).
Calibration age from Koester and Lifton (2023): 50000 ± 500 yr.
Isostatic adjustment calibration data: Gowan2021.

SP lava flow, Arizona, USA
Data from Fenton et al. (2019) and Koester and Lifton (2023).
Calibration age of 72000 ± 2000 yr from Fenton et al. (2019) based on 40Ar/39Ar dating.
Isostatic adjustment calibration data: Gowan2021.

Lake Bonneville shoreline, W USA
Data from Lifton et al. (2015) and Koester and Lifton (2023).
Calibration age based on 14C ages and U-series data (Lifton et al. 2015) with an IntCal09 age of
18300 ± 300 cal BP. Back-calculation with IntCal09 yields a 14C age of 15119 ± 279 yr BP, which,
calibrated with IntCal20, yields an age of 18427 ± 299 cal BP. Plus 55 years for sampling year.
Uncertainty kepts as 300 years.
Isostatic adjustment calibration data: ICE7G.

Marrait moraine, W Greenland
Data from Young et al. (2014) and Koester and Lifton (2023).
Sampling year based on sample names.
Calibration age based on two min and two max 14C ages from Young et al. (2013) calibrated with the
IntCal20 calibration curve using the Bayesian approach of Martin et al. (2015). This yields a
calibration age of 9174 ± 61 cal BP. Plus 61 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Scotland (Corrie nan Arr + Maol Chean-dearg)
Data from Borchers et al. (2016) and Koester and Lifton (2023).
Calibration age 11700 cal BP from Borchers et al. (2016) based on Greenland ice core chronology.
Plus 56 years for sampling year. Calibration age uncertainty set to 500 yr (300 yr in Borchers et
al. 2016) in light of conflict regarding Scotland YD deglaciation (see site Rannoch Moor above).
Isostatic adjustment calibration data: ICE7G.

Chile
Data from Borchers et al. (2016) and Koester and Lifton (2023).
Calibration age from Koester and Lifton (2023): 50000 ± 500 yr.
Isostatic adjustment calibration data: Gowan2021.

Macaulay valley debris flow, New Zealand
Data from Putnam et al. (2010), Schimmelpfennig et al. (2012), and Koester and Lifton (2023).
Calibration age based on ten 14C dates from organic material buried below the debris flow in Putnam
et al. (2010) yielding a weighted mean 14C age of 8755.3 ± 51.6 BP. Calibration against the SHCal20
calibration curve yields an age of 9705 ± 112 cal BP. Plus 58 years for sampling year.
Isostatic adjustment calibration data: ICE7G.

Antarctica
Data from Borchers et al. (2016) and Koester and Lifton (2023).
Calibration age from Koester and Lifton (2023): 50000 ± 500 yr.
Isostatic adjustment calibration data: Gowan2021.
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