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This Article Full Text (PDF) All Versions of this Article: B26271.1v1 121/7-8/1013    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Phillips, F. M Articles by Clark, D. H Search for Related Content GeoRef GeoRef Citation

Glacial geology and chronology of Bishop Creek and vicinity, eastern Sierra Nevada, California

¹ Earth & Environmental Science Department, New Mexico Tech, Socorro, New Mexico 87801, USA
² Department of Hydrology & Water Resources, University of Arizona, Tucson, Arizona 85712, USA
³ Earth & Environmental Science Department, New Mexico Tech, Socorro, New Mexico 87801, USA
⁴ Purdue Rare Isotope Measurement Laboratory, Physics Department, Purdue University, West Lafayette, Indiana 47907-1396, USA
⁵ Department of Geology, Western Washington University, Bellingham, Washington 98225-9080, USA

The valley of Bishop Creek, which drains part of the eastern flank of the Sierra Nevada, California, contains an unusually well-preserved set of middle to late Quaternary moraines. These deposits have been mapped by previous investigators, but they have not been quantitatively dated. We used the accumulation of cosmogenic ³⁶Cl to assign a chronology to the maximal glacial positions mapped in the valley. Our results indicate that the terminal moraines mapped by previous investigators as Tahoe were all deposited between ca. 165 and ca. 135 ka, during marine isotope stage (MIS) 6. Moraines mapped as Tioga were deposited between 28 and 14 ka, during MIS 2. These can be subdivided into Tioga 1 (28-24 ka), Tioga 3 (18.5-17.0 ka), and Tioga 4 (16.0-14.5 ka) advances (no moraines dated to Tioga 2 [21-19 ka] were found, presumably because the Tioga 3 advance either overrode or fluvially eroded them). At 15.0-14.5 ka, the Tioga 4 glacier retreated abruptly to the crest of the range. This was followed by the brief and fairly minor Recess Peak advance at ca. 13.4 ka. No Holocene advances extended beyond the very restricted limits of ice during the Matthes (Little Ice Age) advance. All preserved terminal moraines at lower elevations were deposited during either the Tahoe or Tioga stades. The Tahoe terminal moraines are extensive and voluminous, whereas the Tioga moraines are relatively narrow and have small volumes. However, this notable difference may be more a result of idiosyncrasies in the local glacial history than the result of differences in the length or intensity of glaciation between the two glacial episodes. The history of glacial advances at Bishop Creek exhibits a strong correspondence to global climate cycles, and to paleoclimate events in the North Atlantic in particular.