advances.sciencemag.org/cgi/content/full/4/5/eaar5040/DC1

Supplementary Materials for

Deglaciation of the Pacific coastal corridor directly preceded the human

colonization of the Americas

Alia J. Lesnek, Jason P. Briner, Charlotte Lindqvist, James F. Baichtal, Timothy H. Heaton

Published 30 May 2018, Sci. Adv. 4, eaar5040 (2018)

DOI: 10.1126/sciadv.aar5040

This PDF file includes:

fig. S1. Map of southeastern Alaska with labeled islands.

fig. S2. Representative boulder and bedrock samples collected for 10Be dating.

fig. S3. Normal kernel density estimates of 10Be ages.

fig. S4. Fossilized mammal bone 14C ages from caves in southeastern Alaska.

fig. S5. Box-and-whisker plot of fossilized cave bone δ13C values from Prince of

Wales Island.

fig. S6. Sensitivity testing of the fossilized cave bone 14C age calibration.

fig. S7. Fossilized cave bone δ13C values and marine carbon percentages through

time.

table S1. 10Be sample information.

table S2. 10Be ages calculated with alternative production rates and scaling

schemes.

table S3. Fossilized cave bone sample information used for 14C calibration.

Reference (66)

fig. S1. Map of southeastern Alaska with labeled islands. Shuká Káa on Prince of

Wales Island is denoted by the orange star.

fig. S2. Representative boulder and bedrock samples collected for 10Be dating. (A-

B) Bedrock samples from Dall Island. (C) Perched boulder from Suemez Island. (D)

Bedrock sample from the abraded surface of a rôche moutonée at Suemez Island. (E-F)

Perched boulders from a cirque on Baker Island. (G) Bedrock sample from Warren

Island. The old apparent 10Be age of this sample is due to cosmogenic nuclide

inheritance from previous exposure. (H) Perched boulder sample from Warren Island.

fig. S3. Normal kernel density estimates of 10Be ages. In both panels, individual 10Be

ages are represented by the gray lines and the thicker black line represents the

summed probability distribution of the entire 10Be age population. (A) 10Be ages from a

cirque on Baker Island. Average excludes one outlier from a bedrock surface (15SEAK-

11; 17.0 ± 0.7 ka) that is >3 SD older than the remaining three 10Be ages. (B) 10Be ages

from perched boulders and bedrock at Dall, Suemez, and Warren Islands. Average age

excludes one outlier from a bedrock surface (17SEAK-12; 24.8 ± 1.0 ka) that is >3 SD

older than the remaining nine 10Be ages.

fig. S4. Fossilized mammal bone 14C ages from caves in southeastern Alaska. (A)

Summed probability distribution of all ages. Dark green line = Shuká Káa; light green

line = all other caves. (B) Fossilized mammal bones by species. Dots represent the

mean of the total range of each calibrated 14C age. Vertical gray bar denotes the timing

of maximum CIS extent in southeastern Alaska.

Cal ka BP

fig. S5. Box-and-whisker plot of fossilized cave bone δ13C values from Prince of Wales Island. Fossils are grouped

by species. White boxes show the Q1-Q3 interquartile range, and the horizontal black line in each box denotes the

median. Black circles represent the average δ13C value for each species, and white circles denote outliers which have

δ13C values exceeding 1.5 times the Q1-Q3 interquartile range from the median. Blue shading shows the divisions

between various percentages of marine carbon used for the 14C age calibration.

fig. S6. Sensitivity testing of the fossilized cave bone 14C age calibration. Under

multiple calibration schemes, a hiatus in fossil 14C ages (blue arrow) appears from ~20-

17 ka.

Cal ka BP

20.17 ± 0.59 to 17.36 ± 1.20 cal ka BP

19.80 ± 0.60 to 16.62 ± 1.29 cal ka BP

20.18 ± 0.59 to 17.1 ± 1.23 cal ka BP

fig. S7. Fossilized cave bone δ13C values and marine carbon percentages through

time. Blue dots = 100% marine carbon; teal dots = 50% marine; green dots = 0%

marine. Hiatus in fossil ages from ~20-17 ka, which is interpreted as CIS cover of the

Alexander Archipelago, is indicated by the gray bar.

Age (cal ka BP)

table S1. 10Be sample information.

table S2. 10Be ages calculated with alternative production rates and scaling schemes.

table S3. Fossilized cave bone sample information used for 14C calibration.

table S3, continued

table S3, continued

table S3, continued