Abstract
Cosmogenic surface-exposure ages from boulders on a terminal moraine complex establish the timing of the local last glacial maximum (LGM) in the Taylor River drainage basin, central Colorado. Five zero-erosion 10Be ages have a mean of 19.5±1.8 ka while that for three 36Cl ages is 20.7±2.3 ka. Corrections for modest rates (∼1 mm ka-1) of boulder surface erosion result in individual and mean ages that are generally within 2% of their zero-erosion values. Both the means and the range in ages of individual boulders are consistent with those reported for late Pleistocene moraines elsewhere in the southern and middle Rocky Mountains, and thus suggest local LGM glacier activity was regionally synchronous. Two anomalously young (?) zero-erosion 10Be ages (mean 14.4±0.8 ka) from a second terminal moraine are tentatively attributed to the boulders having been melted out during a late phase of ice stagnation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 494-499 |
| Number of pages | 6 |
| Journal | Quaternary Science Reviews |
| Volume | 26 |
| Issue number | 3-4 |
| DOIs | |
| State | Published - Feb 2007 |
Bibliographical note
Funding Information:This pilot study was made possible through a Grant-In-Aid of Research from the University of Minnesota. Personnel from PRIME Lab at Purdue University, particularly David Elmore, were extremely helpful during the sampling phase of the project and in the subsequent analysis of the AMS results. Andy Moses assisted in the field. Discussions and assistance from Kurt Refsnider and Larry Benson are gratefully acknowledged. Comments from Ed Brook and two anonymous reviewers improved the manuscript.