Geomorphologic evidence provided by late Holocene glacial advances demonstrates the sensitivity of central Brooks Range to changes in temperature and moisture balance over decadal to centennial timescales. High-resolution climate proxy records covering the middle to late Holocene are sparse from this region. One exception is Blue Lake, a small (<0.5 km2), shallow (4.7 m), glacier-fed lake set on the crest of the Brooks Range (68º05.3 N, 150º27.8 W) in north-central Alaska at an altitude of 1265 m. The 4 km2 watershed contains a small cirque glacier located on the north face of the 1890 m high headwall, on the north side of the continental divide. Field observations and air photos indicate that melt-water from the glacier contributes a substantial quantity of fine-grained sediment to the lake. Sediment cores recovered in August of 1999 contain millimeter-scale laminations comprised of lamina couplets, which exhibit the classic mode of varve formation in a glacial basin consisting of a succession of fine sands to silts deposited during the summer months, followed by a well-defined winter clay cap. In addition to annual variability in varve thickness, long-term trends in thickness were identified and compared with the historical climate record. Blue Lake records the glacial response to late Holocene climate phenomena, such as the Little Ice Age (cooling), Medieval Climatic Anomaly (warming), and the 20th century warming trend.Varve measurements from Blue Lake correlate well with regional cooling and warming trends described for the late Holocene from other proxy records across the Arctic.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12092004-173041 |
| Date | 02 February 2005 |
| Creators | Osgood, Barbara Gabriele |
| Contributors | Mark Abbott, Mike Rosenmeier, Charles Jones |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12092004-173041/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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