Wrangell Mountain /St. Elias Study Glacial Record

A. Summary of the glacial geologic data from the Wrangell-St. Elias glacier study.

Graphic 1

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Summary diagram showing radiocarbon ages, tree-ring crossdates and estimated moraine ages. (a). Early advances are determined by radiocarbon ages from the outer rings of killed trees. Bars represent the two sigma range of each date, which is used when assessing age equivalence. See Table 1 for a list of radiocarbon ages and their significance. (b). Tree-ring crossdates on logs overrun by ice at five of the nine glacial forefields. The living tree-ring records used in the dating are from the Tana Dunes and the Big Bend Lake ring-width series from the area south of the Wrangells and the Silvertip composite ring-width data from north of the Wrangells Mountains (Fig. 1). Shaded bars on (a) and (b) are general intervals of ice advance. (c). Histogram showing the minimum ages on 20 moraines from the nine glacier forefields. Minimum ages are assigned based on tree-ring and lichen ages. The black blocks are the outer-most moraines at individual glaciers. 

B. Comparison of the Wrangell Mountain record with the coastal record and the glacier record from the adjoining St. Elias Mountains.

Glacier Study 2

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Correlation diagrams showing the relationship among the glacial chronologies for the past two millennia for the (a) the Gulf Coast of Alaska (Barclay, unpublished data; Calkin et al., 2001; McAllister et al., 2000; Wiles et al., 1999a, b, Yager et al., 1998); (b) the Wrangell Mountains (this study); and (c) the White River area in the St. Elias Mountains (Denton and Karlén, 1977). Radiocarbon ages are labeled with lab numbers and bars represent the two sigma calibrated intervals. Black lines represent logs dated using dendrochronology.

References:

Calkin, P.E., Wiles, G.C., and Barclay, D.J., 2001, Holocene coastal glaciation of Alaska: Quaternary Science Reviews, v. 20, p. 449-461.

Denton, G. H. and Karlén, W., 1977, Holocene glacial and tree-line variations in the White River Valley and Skolai Pass, Alaska and Yukon Territory: Quaternary Research, v. 7, p. 63-111.

Wiles, G.C., Barclay, D., and Calkin, P.E., 1999a, Tree-ring dated Little Ice Age histories of maritime glaciers from western Prince William Sound, Alaska: The Holocene, v. 9, p. 163-173.

Wiles, G.C., Post, A., Muller, E.H., and Molnia, B.F. 1999b, Dendrochronology and late Holocene history of the Bering Piedmont Glacier, Alaska: Quaternary Research, v. 52, p. 185-195.

Yager, E.M., Barclay, D.J., Calkin, P.E. and Wiles, G.C., 1998, Tree-ring based history of Sheridan Glacier, southern Alaska: Geological Society of America Abstracts with Programs, North-Central Section, Columbus, Ohio, March 19-20,