Download or read book Late Holocene Glacial Advances in the Klamath Mountains Northern California Determined from 10Be Cosmogenic Exposure Dating and Dendrochronology written by Joshua Tate Graham and published by . This book was released on 2013 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The well-preserved moraines in the cirque at the head of Grizzly Creek, Klamath Mountains, California, provide the most complete record of late-Holocene glacier fluctuations yet documented in this region. Two separate moraine complexes lie below the modern glacier, within the cirque, only one of which supports substantial tree growth. 10Be cosmogenic ages of scoured bedrock surfaces and moraine boulders, as well as tree-ring ages indicate the approximate timing of glacial maxima in the Grizzly Valley cirque. The combination of the detailed climate record, provided by tree-ring widths, and the estimated moraine ages, determined from dendrochronology and cosmogenic dating, allows for an accurate reconstruction of the Grizzly Valley Glacier fluctuations over the last 1,000 years.

Download or read book Chronology and Paleoclimate of Late Pleistocene Glaciation in the Klamath Mountains CA written by Nathan W. Dickey and published by . This book was released on 2016 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glaciers are sensitive to local and global climate variations, especially to changes in precipitation and temperature over sub-millennial timescales. Therefore, glacial deposits are excellent tools for reconstructing past climates. The western United States exhibits an excellent record of glaciation, but ongoing work across the region shows complex and yetunexplained variation in timing and extent of deglaciation between different mountain ranges at the end of the Last Glacial Maximum (LGM). The Trinity Alps of the southern Klamath Mountains in Northern California contain an excellent record of Pleistocene glaciation which I use to fill a significant spatial gap in published glacial chronologies and to provide a bridge between the Sierra Nevada and the Cascades. The Trinity Alps Wilderness is a 2,130 sq. km. federally designated area located at 41.00° N, 123.00°W, approximately 60 km southwest of Mt. Shasta in Northern California. Glacial deposits in the Trinity Alps were located using Google Earth and previously published maps, and were confirmed in the field. Building on a series of previous expeditions, in the summer of 2015 twenty-four samples from five moraines were taken for 10Be exposure dating, as well as three samples from striated bedrock. Of these, six samples were selected for exposure age analysis: five from two early LGM moraines and one from an older moraine. These ages, in addition to twenty-four ages determined in a previous study, provide evidence for at least two stages of post-LGM glaciation of similar extent throughout the Trinity Alps: the first ending at 16.83 ± 1.85 ka, the second at 12.29 ± 1.23 ka. These ages correlate with the regional LGM (~17 ka) and the global Younger Dryas (~12 ka) cooling event, respectively. The moraine maps were then used to constrain results from a climate-driven 2D numerical model of glacier mass balance and flow. This model was used to determine the potential precipitation and temperature difference from modern climate that would generate the mapped glaciers. Comparison of the resulting paleoclimate curves with nearby proxies and global climate models suggest that an approximate 5.5°C decrease in temperature and 0 to 25% increase in precipitation drove LGM glaciation in the region. Additionally, these results suggest that a similarly wet but slightly warmer-than-LGM climate drove a regionally asynchronous re-advance in the Trinity Alps linked with the Younger Dryas cooling event.

Download or read book Late Quaternary Glacier Fluctuations at Picayune Lake Northern California written by Aidan Patrick Cowan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Klamath Mountains are a 233-km-long (north to south) mountain range located in northern California that shows extensive geomorphic evidence of Pleistocene glaciation. Within the Klamath’s there are many highland lakes, which record evidence of glacial deposition, one of which is Picayune Lake. Lake sediment data collected from Picayune Lake offers insights into the glaciation, and broader depositional history of the Picayune Lake Valley, as well as the climate history of the Klamath Mountains region. I measured magnetic susceptibility, loss on ignition, and grain size in sediment cores and used radiocarbon dating to determine a chronology of glacier fluctuations in the valley. The data show that deglaciation occurred as recently as 11,340 ± 660 cal yr BP and as late as 13,610 ± 120 cal yr BP. Middle Holocene records from Picayune Lake record an inwash of coarse sediments at 7140 ± 690 cal yr BP, as well as deposition of an unsourced tephra at 5640 ± 310 cal yr BP. Late Holocene records from Picayune Lake record layers of coarse sediment at 2490 ± 450 cal yr BP and 1530 ± 220 cal yr BP that I interpret as sediment being washed off the surrounding landscape and deposited into the lake. A second tephra was found at 870 ± 200 cal yr BP, which may have originated from the Little Glass Mountain eruption in northeastern California. The sedimentological record shows no evidence of late Holocene glacier renewal at this site, similar to other low elevation cirques in the region.

Download or read book Regional Correlations of Late Pleistocene Climatic Changes Based on Cosmogenic Nuclide Exposure Dating of Moraines in Idaho written by Cody Sherard and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple post-last glacial maximum (LGM) moraines occur in the Sawtooth Range of the Rocky Mountains in central Idaho. Although relative ages of the moraines have been studied, few numerical ages exist for these moraine sequences. In this study, the ages of LGM and late glacial (Younger Dryas) moraines in the Redfish Lake drainage of Idaho are constrained with 23 new, cosmogenic, 10Be dates. Results of this study include developing a new chronology for the Redfish Lake late Pleistocene moraines that are consistent with regional morainal ages. New cosmogenic 10Be data from boulders on Bull Lake moraines at Redfish Lake are consistent with other dates obtained from Bull Lake moraines elsewhere in the Rocky Mountains. Ages of 107 to 206 ka and 238 to 323 ka suggest synchroniety with other Bull Lake glacial advances in the Wind River Range, Tetons, and Yellowstone. New cosmogenic 10Be data from boulders on terminal moraines in Redfish Lake valley, Idaho, show a LGM at 18.5 ± 0.9 ka to 15.6 ± 0.8 ka, recessional (or minor readvance) moraines deposited between 15.4 ± 0.7 ka and 14.2 ± 0.7 ka; and a Younger Dryas (YD) phase at 11.4-11.7 ± 0.5 ka. Boulders on an LGM moraine at Alturas Lake, Idaho were 10Be dated in order to supplement and test the existing concepts of glaciation there. Ages of 17.2 ± 1.0 ka and 16.8 ± 0.8 ka indicate that this moraine is late Pinedale, not mid-Pinedale as previously suggested by Thackray et al. (2004). The late Pleistocene ice chronology at Redfish Lake is consistent with the glacial chronology in the Wind River Range, WY (LGM 24 ka to l8 ka; recessional deposits 18 ka to 16 ka and YD 11.5 ka); Yellowstone, WY (LGM advances: 29.5-22.5 ka, and 19.5- 5.5 ka); Wallowa Mountains, OR (two 10Be dated LGM advances: 21.1 ± 0.4 ka and 17.0 ± 0.3 ka, and YD advance: 10.2 ± 0.6 ka); Crowfoot Lake, Canada (YD advance: 11,330 ± 220-10,100 ± 70 14C yrs B.P.); and many other places throughout western North America. This research provides chronological constraints on Pinedale LGM (~18.5 ka) moraines, Pinedale recessional (between 18.5 and 14.2 ka) moraines, and Younger Dryas (~11.4 ka) moraines in the Sawtooth Range of the Rocky Mountains, and assists in determining the areal extent of the late Pleistocene cold period in the Western United States.

Download or read book Extent Timing and Climatic Significance of Latest Pleistocene and Holocene Glaciation in the Sierra Nevada California written by and published by . This book was released on 1995 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite more than a century of study, scant attention has been paid to the glacial record in the northern end of the Sierra Nevada, and to the smaller moraines deposited after the retreat of the Tioga (last glacial maximum) glaciers. Equilibrium-line altitude (ELA) estimates of the ice fields indicate that the Tioga ELA gradients there are consistent with similar estimates for the southern half of the range, and with an intensification of the modern temperature/precipitation pattern in the region. The Recess Peak advance has traditionally been considered to be mid-Neoglacial age, about 2--3,000 yr B.P., on the basis of relative weathering estimates. Sediment cores of lakes dammed behind moraines correlative with Recess Peak in four widely spaced sites yields a series of high-resolution AMS radiocarbon dates which demonstrate that Recess Peak glaciers retreated before (approximately) 13,100 cal yr B.P. This minimum limiting age indicates that the advance predates the North Atlantic Younger Dryas cooling. It also implies that there have been no advances larger than the Matthes in the roughly 12,000 year interval between it and the Recess Peak advance. This finding casts doubt on several recent studies that claim Younger Dryas glacier advances in western North America. The 13,100 cal yr B.P. date is also a minimum age for deglaciation of the sample sites used to calibrate the in situ production rates of cosmogenic 1°Be and 26Al. The discrepancy between this age and the 11,000 cal yr B.P. exposure age assumed in the original calibration introduces a large (> 19%) potential error in late-Pleistocene exposure ages calculated using these production rates.

Download or read book Reconstructing Late Pleistocene Deglaciation and Holocene Glacial Advance Using Lacustrine Sediments and 10Be Exposure Dating Brooks Range Arctic Alaska written by Michael E. Badding and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is among the most sensitive locations to climate change, where feedback mechanisms involving the cryosphere result in climate amplification. Because of their sensitivity to summer temperature and winter precipitation, glaciers can be used as proxies for climate change and reconstructions of past glacier fluctuations provide details about paleoclimate. Here, a chronology of late Pleistocene deglaciation and Neoglacial growth is constructed for two valleys in the north-central Brooks Range, Arctic Alaska. Cosmogenic 10Be exposure dating was used on ice-sculpted valley-bottom bedrock outcrops and boulders from Holocene moraine crests. Both valleys show evidence of retreat from the range front ~16-15 ka, and retreat into individual cirques by ~14 ka. There is no evidence for a standstill or re-advance during Late Glacial (14-11 ka) time. Neoglaciation was underway during the middle Holocene, constrained by a moraine dated to 4. 6±0. 5 ka.^Using this moraine age, and another moraine dated at 2. 7±0. 2 ka, this project confirms the accuracy of the previously established lichen growth curve to estimate moraine ages. This project also confirms that glaciers during early Neoglaciation had equal or larger extents than during the Little Ice Age (1200-1900 AD). Sediments collected from a proglacial lake downvalley of modern cirque glaciers reveal episodic sediment deposition from which it is difficult to isolate a signal of glacier advance. Comparing the lake sediment data to the moraine chronology suggests that Upper Kurupa Lake, based on the measured proxies, does not record glacial advances. Several conditions within the lake's catchment likely obscures any glacial signal. Further, more detailed measurements on the lake sediment might reveal additional clues on glacier activity.^Despite the apparent lack of recording changes in glacial length, sediment characteristics suggest a period of stable deposition since 1300 AD, possibly attributed to cooling during the Little Ice Age.

Download or read book Reconstructing Late Pleistocene and Holocene Glacier Fluctuations Using Cosmogenic 10Be Exposure Dating and Lacustrine Sediment Brooks Range Arctic Alaska written by Elizabeth Grayce Ceperley and published by . This book was released on 2014 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to cryosphere-albedo feedbacks mechanisms, climate change is amplified in the Arctic, making it sensitive to changes in temperature. Alpine glaciers grow and retreat depending on climate, and are excellent recorders of past climate fluctuations. By analyzing the landforms and sediment deposited by glaciers, high-resolution climate chronologies can be constructed and past glacier fluctuations can be inferred. 10Be ages and physical properties of lake sediment are used here to reconstruct Late Pleistocene and Holocene glacier activity from Alapah River valley and Shainin Lake in the north-central Brooks Range. 10Be ages from moraine boulders in Alapah River valley in the north-central Brooks Range were used to reconstruct the maximum glacier extent during the LGM. After eliminating outliers, the 10Be ages from a terminal moraine deposit in the Alapah River valley indicate that the local LGM culminated at 21. 0 ℗ł 0. 8 ka. This new 10Be chronology is the first to firmly constrain the timing of the local LGM in the Brooks Range, and is in agreement with LGM moraine records from other sites in Alaska and the globe. Two 10Be ages from boulders located on bedrock 14 km upvalley from the Itkillik II terminal moraine give an age of deglaciation in Alapah River valley of 18. 2 ℗ł 0. 8 ka. This indicates rapid retreat after the LGM and shows that deglaciation is synchronous with sites in Alaska but was initiated earlier than the age of 17 ka previously proposed for onset of LGM deglaciation in the western US. Physical and geochemical properties of lake sediment from a proglacial lake in Alapah River valley, Shainin Lake, were analyzed to investigate any glacial signals recorded in the lake sediment. Age-depth models for each core were established using 14C ages and analytical methods included magnetic susceptibility, wet bulk density (WBD), scanning X-Ray fluorescence (ITRAX) and visible scanning reflectance spectroscopy. The WBD record from Shainin Lake may serve as a proxy for glacial history of Alapah and Kayak Creek valleys. If interpreted correctly, glacial activity increased from 12,700 to ~10,000 cal yr, decreased from ~10,000 to ~5700 cal yr BP, then increased from ~5700 cal yr BP to the present. This indicates that there is evidence for early Holocene glacial activity, the retreating or stagnating glaciers in the middle Holocene until ~5700 cal yr BP, followed by expanding ice.

Download or read book A Late Glacial and Holocene Chronology of the Castner Glacier Delta River Valley Alaska written by Michael W. Howley and published by . This book was released on 2008 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Extension of the Known Area of Pleistocene Glaciation to the Coast Ranges of California written by Ruliff Stephen Holway and published by . This book was released on 1911 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Regional Trends in Holocene Glaciation of the Southeastern Sierra Nevada California written by Michael Wright Trumbower and published by . This book was released on 2011 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Quaternary Glaciations in the Eastern San Bernardino Mountains written by Anne Elizabeth Perez and published by . This book was released on 2003 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 10Be Chronology of Late Pleistocene and Holocene Glaciation of the Alapah Mountain and Arrigetch Peaks Areas Central Brooks Range Alaska written by Simon L. Pendleton and published by . This book was released on 2013 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The amplification of climate change in the Arctic is due to several cyrosphere related feedback mechanisms, making it one of the most climate sensitive environments in the world. Due to this sensitivity, glaciers in this region are excellent recorders of past climate fluctuations. This high-resolution chronology left on the land by these glaciers is an important link in deciphering the dynamic relationship between glaciers and climate, leading to a better understanding of the extent and magnitude of past Arctic climate variability. Here we present new 10Be based glacier chronologies from the late Pleistocene through the Little Ice Age (LIA) for two valleys located in the north- and south-central Brooks range, Alaska. Moraine boulders from the Alapah Mountain moraines on the northern flank of the range indicate that the Itkillik III glaciation culminated by ~17 ka. This age is much older than previous estimates (~15-13 ka) and suggests a revision of the original late Pleistocene glacial chronology. This new Itkillik chronology requires substantial glacial retreat between ~27-23 ka, at the height of the northern hemisphere last glacial maximum (LGM). Due to their moisture sensitivity, expanded Arctic sea ice may have starved glaciers of precipitation during this time. Erratic boulders and scoured bedrock from several valleys in both the northern and southern Brooks Range show that deglaciation was underway by ~16 ka and glaciers retreated rapidly up valley to their Neoglacial limits, in some case by 14. 9 ℗ł 0. 8 ka. Sampled boulders from two Neoglacial moraines show that glaciers reached their maximum Holocene extent by 3. 2 ℗ł 0. 3 ka. In conjunction, these ages show that glaciers remained at or behind their Holocene maximum from ~14-3 ka. This means that Late Glacial (14-11 ka) or early to middle Holocene advances were either absent or less extensive than their Holocene maximum.

Download or read book Late Holocene Glacial History of Manatee Valley Upper Lillooet Provincial Park Southern Coast Mountains British Columbia written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation uses dendrochronologic and radiometric techniques to infer the timing of glacier advance for four ice lobes that are drained by Manatee Creek in a remote valley located in the southern Coast Mountains, British Columbia. Dendroglaciologic evidence exposed by retreating glaciers provides evidence for increasing complexity in the Holocene glacial record, particularly for mid-late Holocene events. Since Holocene ice fronts periodically extended below treeline in the region, previous glacier advances overrode and buried forests beneath till deposits. The dendroglaciologic evidence presented here corroborates the record of glacier advances described for other southern British Columbia Coast Mountain glaciers and details ice front position at ca. 4270 14C yr BP, 3430 14C BP and 2350 14C yr BP. Well-preserved sequences of lateral, nested moraines were mapped and profiled to delineate the boundaries of Manatee and Oluk glaciers. Relative dates provided by lichenometry and dendrochronology were used as limiting dates for the deposition of 5-6 moraines during the late 14th, early 16th, early 18th, 19th, and early-20th Century. Reconstructions of Holocene glacial history offer insight into the regional, climatic regime and add to the discussion about pervasive, millennial-scale cycles.

Download or read book Late Holocene Glacial History of Manatee Valley Upper Lillooet Provincial Park Southern Coast Mountains British Columbia written by Lindsey Koehler and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation uses dendrochronologic and radiometric techniques to infer the timing of glacier advance for four ice lobes that are drained by Manatee Creek in a remote valley located in the southern Coast Mountains, British Columbia. Dendroglaciologic evidence exposed by retreating glaciers provides evidence for increasing complexity in the Holocene glacial record, particularly for mid-late Holocene events. Since Holocene ice fronts periodically extended below treeline in the region, previous glacier advances overrode and buried forests beneath till deposits. The dendroglaciologic evidence presented here corroborates the record of glacier advances described for other southern British Columbia Coast Mountain glaciers and details ice front position at ca. 4270 14C yr BP, 3430 14C BP and 2350 14C yr BP. Well-preserved sequences of lateral, nested moraines were mapped and profiled to delineate the boundaries of Manatee and Oluk glaciers. Relative dates provided by lichenometry and dendrochronology were used as limiting dates for the deposition of 5-6 moraines during the late 14th, early 16th, early 18th, 19th, and early-20th Century. Reconstructions of Holocene glacial history offer insight into the regional, climatic regime and add to the discussion about pervasive, millennial-scale cycles.

Download or read book Late Holocene Climate and Glacier Response Reconstructed Using Stratigraphy and Lichenometry at Iceberg Lake Alaska written by Michael Gregg Loso and published by . This book was released on 2004 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Holocene Climate and Glacier Fluctuations in the Cambria Icefield Area British Columbia Coast Mountains written by Kate Johnson and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the British Columbia Coast Mountains most dendroclimatological and dendroglaciological studies have focused on developing insights from tree-ring sites located in the southern and central regions. By contrast relatively few studies have been conducted in the northwestern Coast Mountains, where exploratory studies reveal that significant climate-radial growth relationships exist. The purpose of this study was to develop a proxy record of climate change from tree rings and to reconstruct the late Holocene glacial history of two outlet glaciers spilling eastward from the Cambria Icefield. Dendroclimate investigations were conducted using mountain hemlock (Tsuga mertensiana) trees growing on three high?elevation montane slopes. The three stands located along a 35 km transect cross date to form a master chronology for the region spanning 409 years (1596 to 2007 A.D.). Correlation analyses show that the radial growth of the regional tree?ring chronology corresponds to variations in the mean June-July-August (JJA) air temperature. The relationship between the two variables was used to reconstruct mean JJA air temperature from 1680 to 2007 A.D.). The reconstruction illustrates warm and cool intervals that are synchronousito those derived from other paleoenvironmental research in this region. The proxy record also highlights annual to inter?decadal climate variability likely resulting from atmospheric-ocean circulation patterns described by the El Ni?no?Southern Oscillation and the Pacific Decadal Oscillation. The late Holocene behaviour of White and South Flat glaciers was investigated using radiocarbon dating techniques, dendrochronological cross?dating techniques and geomorphological analysis of sedimentary units within the White and South Flat glacier forefields. Evidence for a First Millennial Advance (FMA) cumulating around 650 A.D. and early Little Ice Age (LIA) advances at 1200 and 1400 A.D. were documented. These advances are contemporaneous with the late Holocene activity of glaciers throughout the region, suggesting coherent broad-scale climate forcing mechanisms have influence glacial mass balance regimes over at least the last two millennia. The dendroclimatological and dendroglaciological findings of the study provide the first annually?resolved climate record for the region and help to enhance our understanding of late-Holocene glacier behaviour in the Cambria Icefield Area. The thesis documents the complex interactions between climate and the radial growth of mountain hemlock trees in the Pacific Northwest, and describes the role that long?term climate variability played in glacier dynamics during the FMA and LIA.

Download or read book A High resolution Study of a Late Pleistocene Interglacial glacial Transition and Its Periodicity in Owens Lake California Core OL 92 written by Cassaundra Ashley-Rochelle Meyers and published by . This book was released on 2010 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: