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• 61. [Article] An Interdisciplinary approach towards understanding late Pleistocene ice sheet change

  The results presented in this dissertation address a number of questions regarding late Pleistocene and Holocene ice-sheet and climate interactions, spanning disciplines involving paleoclimatology and ...

  Citation × Citation Citation Abstract Copy Title: An Interdisciplinary approach towards understanding late Pleistocene ice sheet change Author: Cuzzone, Joshua The results presented in this dissertation address a number of questions regarding late Pleistocene and Holocene ice-sheet and climate interactions, spanning disciplines involving paleoclimatology and atmospheric science. These studies use various techniques in geochemistry, climate modeling, and ice-sheet modeling to address ice- sheet response to climate and the attendant interactions between the atmosphere and ice- sheets. An important question in paleoclimatology involves the response of past ice sheets to a warming climate, with the end goal of providing context for understanding the response of future ice sheets to anthropogenic warming. A longstanding question regards the timing and rate of retreat for the Scandinavian Ice Sheet (SIS) during the Holocene. Much work has been done to constrain the retreat of the SIS from the last glacial maximum to the well-defined Younger Dryas moraines, however, little is known regarding the SIS Holocene retreat. Presented is a compilation of 87 ¹⁰Be surface exposure ages from Sweden and Norway. These ages provide a high-resolution reconstruction of the SIS deglaciation during the Holocene, and allow for close comparison with proxies of temperature and insolation. The results suggest an asymmetric deglaciation of the SIS, with retreat forced by both a warming climate and and ice-sheet dynamics depending on time and location. The record also provides a means for evaluating the SIS contribution to Holocene sea-level rise. Combining this with estimates from the Laurentide Ice Sheet and the Greenland Ice Sheet, our results suggest that ~23 m of residual sea-level rise exists at the start of the Holocene. We suggest an Antarctic source, which has implications for understanding the sensitivity of the Antarctic Ice Sheet to Holocene climate change. Ice-sheets exert a large presence on the overlying atmosphere, with these interactions influencing the general circulation and ultimately the surface mass balance of the ice sheet. Prior work has indicated striking differences in the atmospheric circulation between the LGM and present day. Using a fully coupled climate simulation of the last deglaciation, the atmospheric circulation is studied, with respect to the stationary waves and storm tracks. For this study, we focus on the LIS. Our results show an enhanced stationary wave, forced mechanically by the topography of the LIS along western North America, which provides moisture, driven by enhanced ridging. This mechanism provides a positive feedback, whereby a larger ice sheet drives a more positive wintertime mass balance. Eventually, as the ice sheet melts, this stationary wave weakens, and the moisture flux decreases. Over the eastern LIS, coupled atmosphere and ice-sheet dynamics conspire to weaken the storm track at the LGM. As the ice melts, however, the storm track becomes broader and strengthens. The storm track becomes an efficient means for moisture delivery to the eastern LIS, with this relationship strengthening through the deglaciation. We suggest that enhanced wintertime accumulation from the strengthening storm track may have played a strong role in offsetting summertime ablation along the eastern LIS, and thus may be a reason why the LIS terminated over eastern North America. Another longstanding question in paleoclimatology involves the role of CO₂ and insolation on driving the deglaciation of the great Northern hemisphere ice sheets. To investigate this question we one way coupled the 3-dimensional thermomechanical ice- sheet model, Glimmer to climate simulations of the last deglaciation using GENMOM. We first built up a realistic LIS, constrained by the best available reconstructions of the area and volume, by perturbing parameters to obtain the best fit. Once a suitable spun-up LGM LIS was created, we forced the deglaciation of the LIS using climate simulations of the last deglaciation using either varying insolation only, and varying CO₂ only. Our results show similar trends in the deglaciation of the LIS relative to simulations of the deglaciation forced with all forcings (CO₂ and insolation). Upon further inspection, our results prove that the one way coupling scheme is unable to capture the influence of the separate forcings. Instead, the topography boundary condition used to drive the climate simulations dictates the distribution of heat and moisture, and thus the deglaciation. Our results show that in order to properly simulate the response of the LIS to CO₂ and insolation only forcings, an asynchronous coupling scheme or coupled climate-ice-sheet models should be used. Title: An Interdisciplinary approach towards understanding late Pleistocene ice sheet change Author: Cuzzone, Joshua The results presented in this dissertation address a number of questions regarding late Pleistocene and Holocene ice-sheet and climate interactions, spanning disciplines involving paleoclimatology and atmospheric science. These studies use various techniques in geochemistry, climate modeling, and ice-sheet modeling to address ice- sheet response to climate and the attendant interactions between the atmosphere and ice- sheets. An important question in paleoclimatology involves the response of past ice sheets to a warming climate, with the end goal of providing context for understanding the response of future ice sheets to anthropogenic warming. A longstanding question regards the timing and rate of retreat for the Scandinavian Ice Sheet (SIS) during the Holocene. Much work has been done to constrain the retreat of the SIS from the last glacial maximum to the well-defined Younger Dryas moraines, however, little is known regarding the SIS Holocene retreat. Presented is a compilation of 87 ¹⁰Be surface exposure ages from Sweden and Norway. These ages provide a high-resolution reconstruction of the SIS deglaciation during the Holocene, and allow for close comparison with proxies of temperature and insolation. The results suggest an asymmetric deglaciation of the SIS, with retreat forced by both a warming climate and and ice-sheet dynamics depending on time and location. The record also provides a means for evaluating the SIS contribution to Holocene sea-level rise. Combining this with estimates from the Laurentide Ice Sheet and the Greenland Ice Sheet, our results suggest that ~23 m of residual sea-level rise exists at the start of the Holocene. We suggest an Antarctic source, which has implications for understanding the sensitivity of the Antarctic Ice Sheet to Holocene climate change. Ice-sheets exert a large presence on the overlying atmosphere, with these interactions influencing the general circulation and ultimately the surface mass balance of the ice sheet. Prior work has indicated striking differences in the atmospheric circulation between the LGM and present day. Using a fully coupled climate simulation of the last deglaciation, the atmospheric circulation is studied, with respect to the stationary waves and storm tracks. For this study, we focus on the LIS. Our results show an enhanced stationary wave, forced mechanically by the topography of the LIS along western North America, which provides moisture, driven by enhanced ridging. This mechanism provides a positive feedback, whereby a larger ice sheet drives a more positive wintertime mass balance. Eventually, as the ice sheet melts, this stationary wave weakens, and the moisture flux decreases. Over the eastern LIS, coupled atmosphere and ice-sheet dynamics conspire to weaken the storm track at the LGM. As the ice melts, however, the storm track becomes broader and strengthens. The storm track becomes an efficient means for moisture delivery to the eastern LIS, with this relationship strengthening through the deglaciation. We suggest that enhanced wintertime accumulation from the strengthening storm track may have played a strong role in offsetting summertime ablation along the eastern LIS, and thus may be a reason why the LIS terminated over eastern North America. Another longstanding question in paleoclimatology involves the role of CO₂ and insolation on driving the deglaciation of the great Northern hemisphere ice sheets. To investigate this question we one way coupled the 3-dimensional thermomechanical ice- sheet model, Glimmer to climate simulations of the last deglaciation using GENMOM. We first built up a realistic LIS, constrained by the best available reconstructions of the area and volume, by perturbing parameters to obtain the best fit. Once a suitable spun-up LGM LIS was created, we forced the deglaciation of the LIS using climate simulations of the last deglaciation using either varying insolation only, and varying CO₂ only. Our results show similar trends in the deglaciation of the LIS relative to simulations of the deglaciation forced with all forcings (CO₂ and insolation). Upon further inspection, our results prove that the one way coupling scheme is unable to capture the influence of the separate forcings. Instead, the topography boundary condition used to drive the climate simulations dictates the distribution of heat and moisture, and thus the deglaciation. Our results show that in order to properly simulate the response of the LIS to CO₂ and insolation only forcings, an asynchronous coupling scheme or coupled climate-ice-sheet models should be used. Close

• 62. [Article] Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University ...

  Citation × Citation Citation Abstract Copy Title: Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene Author: Ghalambor, Cameron K., Still, Christopher, Rick, Torben C., et al., Sillett, T. Scott To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University Press on behalf of the American Institute of Biological Sciences and is in the public domain. The published article can be found at: http://bioscience.oxfordjournals.org/. Title: Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene Author: Ghalambor, Cameron K., Still, Christopher, Rick, Torben C., et al., Sillett, T. Scott To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University Press on behalf of the American Institute of Biological Sciences and is in the public domain. The published article can be found at: http://bioscience.oxfordjournals.org/. Close

• 63. [Article] Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion

  copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion Author: Chauvin, Annick, Duncan, Robert A., Bonhommet, Norbert, Levi, Saul copyrighted by American Geophysical Union. Title: Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion Author: Chauvin, Annick, Duncan, Robert A., Bonhommet, Norbert, Levi, Saul copyrighted by American Geophysical Union. Close

• 64. [Article] Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones

  This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html.

  Citation × Citation Citation Abstract Copy Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Close

• 65. [Article] Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr

  Copyright 2000 by the American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr Author: Polsky, C. H., Leinen, M., Murray, R. W., Knowlton, C. W., Mix, Alan C. Copyright 2000 by the American Geophysical Union Title: Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr Author: Polsky, C. H., Leinen, M., Murray, R. W., Knowlton, C. W., Mix, Alan C. Copyright 2000 by the American Geophysical Union Close

• 66. [Article] Volcanoes of the Three Sisters region, Oregon Cascades

  Gerald W. Williams Collection

  Citation × Citation Citation Abstract Copy Title: Volcanoes of the Three Sisters region, Oregon Cascades Author: Williams, Howel, 1898-1980 Gerald W. Williams Collection Title: Volcanoes of the Three Sisters region, Oregon Cascades Author: Williams, Howel, 1898-1980 Gerald W. Williams Collection Close

• 67. [Article] Virola dominicana sp. nov., (Myristicaceae) from Dominican amber

  This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019.

  Citation × Citation Citation Abstract Copy Title: Virola dominicana sp. nov., (Myristicaceae) from Dominican amber Author: Poinar, George, Jr., Steeves, Royce This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019. Title: Virola dominicana sp. nov., (Myristicaceae) from Dominican amber Author: Poinar, George, Jr., Steeves, Royce This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019. Close

• 68. [Article] Origin and distribution of the fish fauna of the Harney Basin, Oregon

  A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all ...

  Citation × Citation Citation Abstract Copy Title: Origin and distribution of the fish fauna of the Harney Basin, Oregon Author: Bisson, Peter Andre A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all contain populations derived from the basin's Pleistocene connection with Malheur River of the Snake system. Colonization of many streams took Place during periods of high precipitation; isolation has resulted froth dessicating trends since the last glaciation. Stream capture has apparently facilitated a secondary invasion of fishes into Silvies River from John Day River, a tributary of the lower Columbia. This conclusion is further supported by the presence of several species only in central Silvies River within the basin. Certain populations similar to those occurring in isolated regions of the Harney Basin also exist above the barrier falls of the south fork of John Day River, but this drainage is believed to be another disrupted fragment containing descendants of a more ancient Columbia fauna. Speculation regarding the sequence of radiation of different species throughout the Columbia watershed is aided by distributional patterns and knowledge of hydrographic history. Title: Origin and distribution of the fish fauna of the Harney Basin, Oregon Author: Bisson, Peter Andre A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all contain populations derived from the basin's Pleistocene connection with Malheur River of the Snake system. Colonization of many streams took Place during periods of high precipitation; isolation has resulted froth dessicating trends since the last glaciation. Stream capture has apparently facilitated a secondary invasion of fishes into Silvies River from John Day River, a tributary of the lower Columbia. This conclusion is further supported by the presence of several species only in central Silvies River within the basin. Certain populations similar to those occurring in isolated regions of the Harney Basin also exist above the barrier falls of the south fork of John Day River, but this drainage is believed to be another disrupted fragment containing descendants of a more ancient Columbia fauna. Speculation regarding the sequence of radiation of different species throughout the Columbia watershed is aided by distributional patterns and knowledge of hydrographic history. Close

• 69. [Article] Structure and stratigraphy of the Sheep Mountain area, Centennial Range, Montana-Idaho

  The thesis area includes 44 square miles of the Centennial Range in Beaverhead County, Montana, and Clark County, Idaho. The rocks exposed in the area range in age from Precambrian to Recent and have been ...

  Citation × Citation Citation Abstract Copy Title: Structure and stratigraphy of the Sheep Mountain area, Centennial Range, Montana-Idaho Author: Moran, John Lee The thesis area includes 44 square miles of the Centennial Range in Beaverhead County, Montana, and Clark County, Idaho. The rocks exposed in the area range in age from Precambrian to Recent and have been divided into 23 mapped units. Pre-Belt metamorphic basement rocks are overlain unconformably by 3,433 feet of Paleozoic strata included in eleven formations. These formations represent all of the periods of the Paleozoic except the Ordovician and Silurian. Nine formations represent all the periods of the Mesozoic and total approximately 3,127 feet in thickness. Cenozoic units present in the area are basalts and rhyolites, landslide debris, glacial deposits, and alluvium. The major structure of the thesis area is a fault block that is the result of uplifting and tilting of the east-west trending Centennial Range during the downwarp of the Snake River Plain in late Pliocene and Pleistocene time. No stratigraphic or structural conditions in the thesis area are favorable for the accumulation and entrapment of oil and gas. Phosphorite has been mined from the Phosphoria Formation in the area. Title: Structure and stratigraphy of the Sheep Mountain area, Centennial Range, Montana-Idaho Author: Moran, John Lee The thesis area includes 44 square miles of the Centennial Range in Beaverhead County, Montana, and Clark County, Idaho. The rocks exposed in the area range in age from Precambrian to Recent and have been divided into 23 mapped units. Pre-Belt metamorphic basement rocks are overlain unconformably by 3,433 feet of Paleozoic strata included in eleven formations. These formations represent all of the periods of the Paleozoic except the Ordovician and Silurian. Nine formations represent all the periods of the Mesozoic and total approximately 3,127 feet in thickness. Cenozoic units present in the area are basalts and rhyolites, landslide debris, glacial deposits, and alluvium. The major structure of the thesis area is a fault block that is the result of uplifting and tilting of the east-west trending Centennial Range during the downwarp of the Snake River Plain in late Pliocene and Pleistocene time. No stratigraphic or structural conditions in the thesis area are favorable for the accumulation and entrapment of oil and gas. Phosphorite has been mined from the Phosphoria Formation in the area. Close

• 70. [Article] Calcium carbonate, organic carbon, and quartz in hemipelagic sediments off Oregon : a preliminary investigation

  An analysis of the amounts of calcium carbonate, organic carbon, quartz, and the rates of sediment accumulation in hemipelagic sediments off Oregon has revealed that the accumulation rates of the total sediment, ...

  Citation × Citation Citation Abstract Copy Title: Calcium carbonate, organic carbon, and quartz in hemipelagic sediments off Oregon : a preliminary investigation Author: Peterson, Robert E. An analysis of the amounts of calcium carbonate, organic carbon, quartz, and the rates of sediment accumulation in hemipelagic sediments off Oregon has revealed that the accumulation rates of the total sediment, organic carbon, and quartz were at least twice as high in the late Pleistocene as they were during the Holocene. The accumulation rate of calcium carbonate was at least 8 times as high. There may have been a short transition period at the end of the last glacial stage from about 14,000 to 12,500 years B.P. when the sedimentation rate was very high up to 75 cm/l000 years. There is evidence that the amount of organic carbon in deep-sea sediments is a function of terrigenous influx, of preservation, and possibly of depth of burial in the sediment. Turbidite sequences in the deep-sea environment off Oregon contain much higher amounts of organic carbon in the upper fine-grained portion of the sequence than in the coarser basal sediment of the sequence, indicating that organic carbon is concentrated in the finer and slower settling parts of the flow. In lower continental slope sediments, the greatest amounts of organic carbon are found in the <4 micron size fraction. Title: Calcium carbonate, organic carbon, and quartz in hemipelagic sediments off Oregon : a preliminary investigation Author: Peterson, Robert E. An analysis of the amounts of calcium carbonate, organic carbon, quartz, and the rates of sediment accumulation in hemipelagic sediments off Oregon has revealed that the accumulation rates of the total sediment, organic carbon, and quartz were at least twice as high in the late Pleistocene as they were during the Holocene. The accumulation rate of calcium carbonate was at least 8 times as high. There may have been a short transition period at the end of the last glacial stage from about 14,000 to 12,500 years B.P. when the sedimentation rate was very high up to 75 cm/l000 years. There is evidence that the amount of organic carbon in deep-sea sediments is a function of terrigenous influx, of preservation, and possibly of depth of burial in the sediment. Turbidite sequences in the deep-sea environment off Oregon contain much higher amounts of organic carbon in the upper fine-grained portion of the sequence than in the coarser basal sediment of the sequence, indicating that organic carbon is concentrated in the finer and slower settling parts of the flow. In lower continental slope sediments, the greatest amounts of organic carbon are found in the <4 micron size fraction. Close