Deglaciation of the Colorado Rocky Mountains following the Last Glacial Maximum

E.M. Leonard; B.J.B. Laabs; A.D. Schweinsberg; C.M. Russell; J.P. Briner; N.E. Young

doi:10.18172/cig.3234

Autores/as

E.M. Leonard Department of Geology Colorado College
B.J.B. Laabs Department of Geosciences, North Dakota State University
A.D. Schweinsberg Department of Geology, University at Buffalo
C.M. Russell Department of Geology, Colorado College
J.P. Briner Department of Geology, University at Buffalo
N.E. Young Lamont-Doherty Earth Observatory, Columbia University

DOI:

https://doi.org/10.18172/cig.3234

Palabras clave:

Último Máximo Glaciar, Deglaciación, Colorado, Montañas Rocosas, datación de superficies de exposición cosmogénica

Resumen

La disponibilidad de casi 180 edades de exposición cosmogénica obtenidas en bloques morrénicos y en superficies rocosas pulidas hace posible establecer la temporalidad y carácter del Último Máximo Glaciar local (UMGL) y la subsecuente deglaciación en las Montañas Rocosas de Colorado. Una revisión de las cronologías glaciares y de los resultados de la modelización numérica indica que aunque los glaciares de Colorado respondieron de forma sincrónica, las diferencias en la temporalidad y magnitud del retroceso glaciar después del UMGL sugieren que diversos factores regionales espacialmente variables, posiblemente relacionados con la precipitación, jugaron un papel en el comportamiento de los glaciares junto con factores hemisféricos o globales más uniformes espacialmente. Los glaciares de las cinco cordilleras examinadas alcanzaron su mayor extensión antes de ~19.5 ka y abandonaron sus morrenas más externas entre ~23.5 y 19.5 ka. Las cronologías detalladas de la deglaciación están disponibles para los glaciares de cuatro de las cordilleras. En la Cordillera Sawatch y en las Montañas de Sangre de Cristo los glaciares estuvieron cerca de su máxima extensión durante el UMGL a 17-16 ka, antes de retroceder rápidamente. En las Montañas de San Juan y en la Front Range los glaciares pueden haber comenzado antes su recesión post-UMGL, aunque esta deglaciación temprana aparece representada por solo unas pocas edades en sustrato pulido que potencialmente contiene herencias cosmogénicas pre-UMGL. Con independencia del momento de inicio de la deglaciación, el ascenso de la línea de equilibrio asociado con la deglaciación ocurrió más tempranamente y fue significativamente mayor en las Montañas de San Juan que en cualquier otro lugar de Colorado. Esto sugiere que las Montañas de San Juan, que se localizan bien al suroeste de las otras cadenas, pueden haber experimentado un aumento de precipitación durante el UMGL, como ocurrió en áreas situadas más al sur y el oeste, mientras que las condiciones del UMGL pueden haber sido más secas en las cordilleras del norte y este de Colorado. Un desmoronamiento de este patrón después del UMGL, con descenso de la precipitación en el sur y el oeste y aumento en el norte y el este puede haber dado lugar a diferencias de una cordillera a otra en Colorado. La deglaciación fue casi completa en las cuatro cordilleras hacia 15-13 ka. Aunque algunos registros proxy indican un enfriamiento tardío al final del Younger Dryas no hay claras evidencias morrénicas de reavance glaciar en ese periodo.

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Biografía del autor/a

E.M. Leonard, Department of Geology Colorado College

Professor of Geology

Citas

Andersen, K.K., Svensson, A., Johnsen, S.J., Rasmussen, S.O., Bigler, M., Röthlisberger, R., Ruth, U., Siggaard-Andersen, M.L., Steffensen, J.P., Dahl-Jensen, D., Vinther, B.M., Clausen, H.B. 2006. The Greenland ice core chronology 2006, 15-42ka. Part 1: Constructing the time scale. Quaternary Science Reviews 25, 3246-3257. http://doi.org/10.1016/j.quascirev.2006.08.002.

Anderson, L.S., Roe G.H., Anderson, R.S. 2014. The effects of interannual climate variability on the moraine record. Geology 42, 55-58. http://doi.org/10.1130/G34791.1.

Asmerom, Y., Polyak, V. J., Burns, S. J. 2010. Variable winter moisture in the southwestern United States linked to rapid glacial climate shifts. Nature Geoscience 3, 114-117. http://doi.org/10.1038/NGEO754.

Atwood Jr., W. W. 1937. Records of Pleistocene glaciers in the Medicine Bow and Park Ranges. Journal of Geology 45, 113-140.

Atwood, W.W., Mather, K.F. 1932. Physiography and Quaternary geology of the San Juan Mountains, Colorado. U.S. Geological Survey Professional Paper 166.

Balco, G. 2011. Contributions and unrealized potential contributions of cosmogenic-nuclide exposure dating to glacier chronology, 1990-2010. Quaternary Science Reviews 30, 3-27. http://doi.org/10.1016/j.quascirev.2010.11.003.

Balco, G., Stone, J., Lifton, N. Dunai, T. 2008. A complete and easily accessible means of calculating surface exposure ages or erosion rates from 10Be and 26Al measurements. Quaternary Geochronology 3, 174-195. http://doi.org/10.1016/j.quageo.2007.12.001.

Bartlein, P.J., Anderson, K.H., Anderson, P.M., Edwards, M.E., Mock, C.J., Thompson, R.S., Webb, R.S., Webb, T. III, Whitlock, C. 1998. Paleoclimatic simulations for North America over the past 21,000 years: features of the simulated climate and comparisons with paleoenvironmental data. Quaternary Science Reviews 17, 549-585. http://doi.org/10.1016/SO277-3791(98)00012-2.

Benedict, J.B. 1973. Chronology of cirque glaciation, Colorado Front Range. Quaternary Research 3, 584-599.

Benson, L., Madole, R., Phillips, W., Landis, G., Thomas, T., Kubik, P. 2004. The probable importance of snow and sediment shielding on cosmogenic ages of north-central Colorado Pinedale and pre-Pinedale moraines. Quaternary Science Reviews 23, 193-206. http://doi.org/10.1016/j.quascirev.2003.07.002.

Benson, L., Madole, R., Landis, G., Gosse, J. 2005. New data for Late Pleistocene Pinedale alpine glaciation from southwestern Colorado. Quaternary Science Reviews 24, 49-65. http://doi.org/10.1016/j.quascirev.2004.07.018.

Benson, L., Madole, R., Kubik, P, McDonald, R. 2007. Surface-exposure ages of Front Range moraines that may have formed during the Younger Dryas, 8.2 cal ka, and Little Ice Age events. Quaternary Science Reviews 26, 1638-1649. http://doi.org/10.1016/j.quascirev.2007.02.015.

Borchers, B., Marrero, S., Balco, G., Caffee, M., Goehring, B., Lifton, N., Nishiizumi, K., Phillips, F., Schaefer, J., Stone, J. 2016. Geological calibration of spallation production rates in the CRONUS-Earth project. Quaternary Geochronology, 31, 188-198. http://doi.org/10.1016/j.quageo.2015.01.009.

Braconnot, P., Otto-Bliesner, B., Harrison, S., Joussaume, S, Peterchmitt, J.-Y., Abe-Ouchi, A., Crucifix, M. , Driesschaert, E., Fichefet, Th., Hewitt, C. D., Kageyama, M., Kitoh, A., Laîné, A., Loutre, M.-F., Marti, O., Merkel, U., Ramstein, G., Valdes, P., Weber, L. ,Yu, Y., Zhao, Y. 2007. Results of PMIP2 coupled simulations of the mid-Holocene and Last Glacial Maximum - Part 1: experiments and large-scale features. Climate of the Past 3, 261-277. http://www.clim-past.net/3/261/2007.

Briles, C. E., Whitlock, C., Meltzer, D. J. 2012. Last glacial-interglacial environments in the southern Rocky Mountains, USA and implications for Younger Dryas-age human occupation. Quaternary Research 77, 96-103. http://doi.org/10.1016/yqres2011.10.002.

Briner, J.P. 2009. Moraine pebbles and boulders yield indistinguishable 10Be ages: a case study from Colorado, USA: Quaternary Geochronology 4, 299-305. http://doi.org/10.1016/j.quageo.2009.02.010.

Briner, J.P., Kaufman, D.S., Manley, W.F., Finkel, R.C., Caffee, M.W. 2005. Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska. Geological Society of America Bulletin 117, 1108-1120. http://doi.org/10.1130/B25649.1.

Brugger, K.A. 2006. Late Pleistocene climate inferred from the reconstruction of the Taylor River glacier complex, southern Sawatch Range, Colorado. Geomorphology 75, 318-329. http://doi.org/10.1016/j.geomorph.2005.07.020.

Brugger, K.A. 2007. Cosmogenic 10Be and 36Cl ages from Late Pleistocene terminal moraine complexes in the Taylor River drainage basin, central Colorado, USA. Quaternary Science Reviews 26, 494-499. http://doi.org/10.1016/j.quascirev.2006.09.006.

Brugger, K.A. 2010. Climate in the southern Sawatch Range and Elk Mountains, Colorado, USA, during the Last Glacial Maximum: inferences using a simple degree-day model. Arctic, Antarctic and Alpine Research 42, 164-178. http://doi.org/10.1657/1938-4246-42.2.164.

Brugger, K.A., Goldstein, B.S., 1999. Paleoglacier reconstruction and late-Pleistocene equilibrium-line altitudes, southern Sawatch Range, Colorado. In: D.M. Mickelson, J.W. Attig (Eds.), Glacial Processes Past and Present. Geological Society of America Special Paper 337, 103-112.

Brugger, K.A., Refsnider, K.A., Leonard, E.M. 2009. Late Pleistocene climate on the Blanca Massif, Sangre de Cristo Mountains, Colorado. Geological Society of America Abstracts with Programs 41, 640.

Clark, P.U., Dyke, A.S., Shakun, J.D., Carlson, A.E., Clark, J., Wohlfarth, B., Mitrovica, J.X., Hostetler, S.W., McCabe, A.M. 2009. The Last Glacial Maximum. Science 325, 710-714. http://doi.org/10.1126/science.1172873.

Dahms, D. E. 2004. Glacial limits in the middle and southern Rocky Mountains, USA, south of the Yellowstone Ice Cap. In: J. Ehlers, P.L. Gibbard (Eds.), Quaternary Glaciations—extent and chronology, part II, Developments in Quaternary Sciences 2. Elsevier, Amsterdam, pp. 275-288.

Davis, P. T., Birkeland, P.W., Caine, N., Rodbell, D.T. 1992. New radiocarbon ages from cirques in Colorado Front Range. Geological Society of America Abstracts with Programs 24, 347.

Dühnforth, M., Anderson, R. S. 2011. Reconstructing the glacial history of green lakes valley, North Boulder Creek, Colorado Front Range. Arctic, Antarctic, and Alpine Research, 43 (4), 527-542. http://doi.org/10.1657/1938-4246-43.4.527.

Fountain, A.G. 2006. Glaciers online: Glaciers of the American West. Available online at: http://glaciers.research.pdx.edu (last access 28/12/2016).

Gosse, J. C., Klein, J., Evenson, E. B., Lawn, B., Middleton, R. 1995. Beryllium-10 dating of the duration and retreat of the last Pinedale glacial sequence. Science 268, 1329-1329. http://doi.org/10.1126/science-268.5215.1329.

Graf, W.L. 1977. The distribution of glaciers in the Rocky Mountains of the United States. Journal of Glaciology 18, 325-328.

Guido, Z.G., Ward, D.J., Anderson, R.S. 2007. Pacing the post-Last Glacial Maximum demise of the Animas Valley glacier and the San Juan Mountain ice cap, Colorado. Geology 35, 739-742. http://doi.org/10.1130/G23596A.1.

Hostetler, S.W., Clark, P.U., 1997. Climatic controls of western U.S. glaciers at the last glacial maximum. Quaternary Science Reviews 16, 505-511. http://doi.org/10.1016/S0277-3791(96)00116-3.

Hostetler, S.W., Bartlein, P.J. 1999. Simulation of the potential responses of regional climate and surface processes in western North America to a canonical Heinrich event. In P.U. Clark, R.S. Webb, L.D. Keigwin (Eds.), Mechanisms of global climate change at millennial timescales, American Geophysical Union Geophysical Monograph 12, 313-327.

Jiménez-Moreno, G., Fawcett, P.J., Anderson, R.S. 2008. Millennial-and centennial-scale vegetation and climate changes during the late Pleistocene and Holocene from northern New Mexico (USA). Quaternary Science Reviews 27, 1442-1452. http://doi.org/10.1016/j.quascirev.2008.04.004.

Jiménez-Moreno, G., Anderson, R. S., Atudorei, V., Toney, J. L. 2011. A high-resolution record of climate, vegetation, and fire in the mixed conifer forest of northern Colorado, USA. Geological Society of America Bulletin 123, 240-254. http://doi.org/10.1130/B30240.1.

Kessler, M.A., Anderson, R.S., Stock, G. (2006), Modeling topographic and climatic control of east-west asymmetry in Sierra Nevada Glacier length during the Last Glacial Maximum. Journal of Geophysical Research, 111, F02002. http://doi.org/10.1029/2005JF000365. .

Krimmel, R.M. 2002. Glaciers of the conterminous United States: Glaciers of the Western United States. U.S. Geological Survey Professional Paper 13856-J-2. In: R.S. Williams, J.G. Ferrigno (Eds.), Satellite image atlas of glaciers of the world: North America, U.S. Geological Survey Professional Paper 1386-J, pp. J329-J381.

Kutzbach, J.E., Guetter, P.J. 1986. The influence of changing orbital parameters and surface boundary conditions on climate simulations for the past 18,000 years. Journal of Atmospheric Sciences 43, 1726-1759.

Kutzbach, J.E., Ruddiman, W.F. 1993, Model description, external forcing, and surface boundary conditions. In: H.E. Wright, Jr, J.E. Kutzbach, T. Webb III, W.F. Ruddiman, F.A. Street-Perrott, P.J. Bartlein (Eds.), Global Climates since the last glacial maximum. University of Minnesota Press, Minneapolis, pp. 12-23.

Kutzbach, J. E., Wright, H. E. 1985. Simulation of the climate of 18,000 years BP: results for the North American/North Atlantic/European sector and comparison with the geologic record of North America. Quaternary Science Reviews 4, 147-187.

Laabs, B. J. C., Plummer, M. A., Mickelson, D. M. 2006. Climate during the Last Glacial Maximum in the Wasatch and southern Uinta Mountains inferred from glacier modeling. Geomorphology 75, 300-317. http://doi.org/10.1016/j.geomorph.2005.07.026.

Laabs, B.J.C., Refsnider, K.A., Munroe, J.S., Mickelson, D.M., Applegate, P.M., Singer, B.S., and Caffee, M.W. 2009. Latest Pleistocene glacial chronology of the Uinta Mountains: support for moisture-driven asynchrony of the last deglaciation: Quaternary Science Reviews 28, 1171-1187. http://doi.org/10.1016/j.quascirev.2008.12.012.

Laabs, B.J.C., Marchetti, D.W., Munroe, J.S., Refsnider, K.A., Gosse, J.C., Lips, E.W., Becker, R.A., Mickelson, D.D., Singer, B. S. 2011. Chronology of latest Pleistocene mountain glaciation in the western Wasatch Mountains, Utah, USA. Quaternary Research 76, 272-284. http://doi.org/10.1016/j.yqres.2011.06.016.

Laabs, B.J.C., Licciardi, J.M., Marchetti, D.W., Leonard, E.M., Munroe, J.S. (in preparation). Cosmogenic 10Be chronology of Pleistocene moraines in the western United States: a synthesis of glacial chronologies and assessment of updated production rates on inferences of paleoclimate. To be submitted to Quaternary Science Reviews, May 2017.

Leonard, E.M. 1984. Late Pleistocene equilibrium-line altitudes and modern snow accumulation patterns, San Juan Mountains, Colorado, U.S.A. Arctic and Alpine Research 16, 65-76.

Leonard, E.M. 1989. Climatic change in the Colorado Rocky Mountains: estimates based on modern climate at late Pleistocene equilibrium lines. Arctic and Alpine Research 21, 245-255.

Leonard, E.M. 2007. Modeled patterns of Late Pleistocene glacier inception and growth in the Southern and Central Rocky Mountains, USA: sensitivity to climate change and paleoclimatic implications. Quaternary Science Reviews 26: 2152-2166. http://doi.org/10.1016/j.quascirev.2007.02.013.

Leonard, E.M., Laabs, B.J.C., Kroner, R.K., Plummer, M.A., Brugger, K.A., Refsnider, K.A., Spiess, V.M., Caffee, M.W. 2017. Late Pleistocene glaciation and deglaciation in the Crestone Peaks area, Colorado Sangre de Cristo Range – chronology and paleoclimate. Quaternary Science Reviews 158, 127-144. http://doi.org/10.1016/jquascirev.2016.11.024.

Licciardi, J.M., Pierce, K.L. 2008. Cosmogenic exposure-age chronologies of Pinedale and Bull Lake glaciations in greater Yellowstone and the Teton Range, USA: Quaternary Science Reviews 27, 814-831. http://doi.org/10.1016/j.quascirev.2007.12.005.

Licciardi, J.M., Clark, P.U., Brook, E.J., Pierce, K.L., Kurz, M.D., Elmore, D., Sharma, P. 2001. Cosmogenic 3He and 10Be chronologies of the late Pinedale northern Yellowstone ice cap, Montana, USA. Geology 29, 1095-1098.

Licciardi, J.M., Clark, P.U., Brook, E.J., Elmore, D., Sharma, P. 2004. Variable responses of western U.S. glaciers during the last deglaciation. Geology 32, 81-84. http://doi.org/10.1130/G19868.1.

Lifton, N., Caffee, M., Finkel, R., Marrero, S., Nishiizumi, K., Phillips, F.M., Goehring, B., Gosse, J., Stone, J., Schaefer, J., Theriault, B., Jull, A.J.T., Fifield, K.,2015. In situ cosmogenic nuclide production rate calibration for the CRONUS-Earth project from Lake Bonneville, Utah, shoreline features. Quaternary Geochronology 26, 56-69. http://doi.org/10.1016/j.quageo.2014.11.002.

Lyle, M., Heusser, L., Ravelo, C., Yamamoto, M., Barron, J., Diffenbaugh, N.S., Herbert, T., Andreasen, D. 2012. Out of the tropics: the Pacific, Great Basin Lakes, and Late Pleistocene water cycle in the western United States. Science 337, 1629-1633. http://doi.org/10.1126/science.1218390.

Madole, R.F. 1969. Pinedale and Bull Lake Glaciation in upper St. Vrain drainage basin, Boulder County, Colorado. Arctic and Alpine Research 1, 279-287.

Madole, R.F. 1980. Time of Pinedale deglaciation in north-central Colorado: Further considerations. Geology 8, 118-122.

Madole, R.F. 1998. Pleistocene glaciation in the upper Platte River drainage basin, Colorado. U.S. Geological Survey Geological Investigations Series map I-2644.

Marcott, S.A., Bauska, T.K., Buizert, C., Steig, E.J., Rosen, J.L., Cuffey, K.M., Fudge, T.J., Severinghaus, J.P., Ahn, J., Kalk, M.L, McConnell, J.R., Sowers, T., Taylor, K.C., White, J.W.C., Brook, E.J. 2014. Centennial-scale changes in the global carbon cycle during the last deglaciation. Nature, 514, 616-619. http://doi.org/10.1038/nature13799.

Meierding, T.C., Birkeland, P.W. 1980. Quaternary glaciation of Colorado. In: H.C. Kent, K.W. Porter (Eds.), Colorado Geology. pp. 165-173.

Meierding, T.C. 1982. Late Pleistocene glacial equilibrium-line altitudes in the Colorado Front Range: a comparison of methods. Quaternary Research 18, 289-310.

Menounos, B., Reasoner, M. A., 1997. Evidence for cirque glaciation in the Colorado Front Range during the Younger Dryas chronozone. Quaternary Research 48, 38-47. http://doi.org/10.1006/qres.1997.1902.

Munroe, J.S., Laabs, B.J.C., Shakun, J.D., Singer, B.S., Mickelson, D.M., Refsnider, K.A., Caffee, M.W., 2006. Latest Pleistocene advance of alpine glaciers in the southwestern Uinta Mountains, Utah, USA: Evidence for the influence of local moisture sources. Geology 34, 841-844. http://doi.org/10.1130/G22681.1.

Oster, J.L., Ibarra, D.E., Winnick, M.J., Maher, K. 2015. Steering of westerly storms over western North America at the Last Glacial Maximum. Nature Geoscience 8, 201-205. http://doi.org/10.1038/NGEO2365.

Parrenin, F., Masson-Delmotte, V., Köhler, P., Raynaud, D., Paillard, D., Schwander, J., Barbante, C., Landais, A., Wegner, A., Jouzel, J. 2013. Science 339, 1060-1063. http://doi.org/10.1126/science.1226368.

Pierce, K.L. 2004. Pleistocene glaciations of the Rocky Mountains. In: A.R. Gillespie, S.C. Porter, B.F. Atwater (Eds.), The Quaternary Period in the United States. Elsevier, Amsterdam, pp. 63-76.

Pigati, J. S., Bright, J. E., Shanahan, T. M., Mahan, S. A. 2009. Late Pleistocene paleohydrology near the boundary of the Sonoran and Chihuahuan Deserts, southeastern Arizona, USA. Quaternary Science Reviews 28, 286-300. http://doi.org/10.1016/j.quascirev.2008.09.022.

Plummer, M.A., Phillips, F.M. 2003. A 2-D numerical model of snow/ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features. Quaternary Science Reviews 22, 1389-1406. http://doi.org/10.1016/S0277-3791(03)00081-7.

Putnam, A.E., Schaefer, J.M., Denton, G.H., Barrell, D.J.A., Birkel, S.D., Andersen, B.G., Kaplan, M.R., Finkel, R.C., Schwartz, R., Doughty, A.M., 2013. The Last Glacial Maximum at 44S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand. Quaternary Science Reviews 62, 114-141. http://doi.org/10.1016/j.quascirev.2012.10.034.

Rasmussen, S.O., Andersen, K.K., Svensson, A.M., Steffensen, J.P., Vinther, B.M., Clausen, H.B., Siggaard‐Andersen, M.L., Johnsen, S.J., Larsen, L.B., Dahl‐Jensen, D., Bigler, M., Röthlesberger, R., Fischer, H., Gotto-Azuma, K., Hansson, M.E., Ruth, U. 2006. A new Greenland ice core chronology for the last glacial termination. Journal of Geophysical Research 111, D06102. http://doi.org/10.1029/2005JD006079.

Ray, L.L. 1940. Glacial chronology of the southern Rocky Mountains. Geological Society of America Bulletin 51, 1851-1918.

Reasoner, M. A., Jodry, M. A. 2000. Rapid response of alpine timberline vegetation to the Younger Dryas climate oscillation in the Colorado Rocky Mountains, USA. Geology 28, 51-54. http://doi.org/10.1130/0091-7613(2000)28<51:RROATV>2.0.CO;2.

Refsnider, K.A., Laabs, B.J.C., Plummer, M.A., Mickelson, D.M., Singer, B.S., Caffee, M.W. 2008. Last Glacial Maximum climate inferences from cosmogenic dating and glacier modeling of the western Uinta ice field, Uinta Mountains, Utah. Quaternary Research 69, 130-144. http://doi.org/10.1016/j.yqres.2007.10.014 .

Refsnider, K.A., Brugger, K.A., Leonard, E.M., McCalpin, J.P., Armstrong, P.P. 2009. Last glacial maximum equilibrium-line altitude trends and precipitation patterns in the Sangre de Cristo Mountains, southern Colorado, USA. Boreas 38, 663-678. http://doi.org/10.1111/j.1502-3885.2009.00097.x.

Richmond, G. M., 1960. Glaciation of the east slope of Rocky Mountain National Park, Colorado. Geological Society of America Bulletin 71, 1371-1382.

Richmond, G. M. 1965. Glaciation of the Rocky Mountains. In: H.E. Wright, Jr, D.G. Frey (Eds.), The Quaternary of the United States. Princeton University Press, Princeton, NJ, pp. 217-230.

Ruleman, C.A., Hudson, A.M. 2016. The Central Colorado Icefield, a mechanism for inception of regional exhumation and deep-canyon incision during the Pleistocene? Geological Society of America Abstracts with Programs 48.

Schaefer, J.M., Denton, G.H. , Barrell, D.J.A., Ivy-Oaks, S., Kubik, P.W., Anderson, B.G., Phillips, F.M., Lowell, T.V., Schlüchter, C. 2006. Near-synchronous interhemispheric termination of the Last Glacial Maximum at mid-latitudes. Science 312, 1510-1513. http://doi.org/10.1126/science.1122872.

Schildgen, T. 2000. Fire and Ice: Geomorphic history of Middle Boulder Canyon as determined by isotopic dating techniques, Colorado Front Range. B.S. Thesis, Williams College, Williamstown, MA, 73 pp.

Schweinsberg, A.D., Briner, J.P., Shroba, R.R., Licciardi, J.M., Leonard, E.M., Brugger, K.A., and Russell, C.M. 2016. Pinedale glacial history of the upper Arkansas River valley: New moraine chronologies, modeling results, and geologic mapping. In: S.M. Keller, M.L. Morgan (Eds.), Unfolding the Geology of the West, Geological Society of America Field Guide 44, pp. 335-353. http://doi.org/10.1130/2016.0044(14).

Shakun, J.D., Clark, P.U., He, F., Marcott, S.A., Mix, A.C., Liu, Z., Otto-Bliesner, B., Schmittner, A., Bard, E. 2012. Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature 484, 49-55. http://doi.org/10.1038/nature10915.

Shakun, J.D., Clark, P.U., He, F., Lifton, N.A., Liu, Z., Otto-Bliesner, B.L. 2015. Regional and global forcing of glacier retreat during the last deglaciation. Nature Communications 6, 8059. http://doi.org/10.1038/ncomms9059.

Thackray, G.D., 2008, Varied climatic and topographic influences on Late Pleistocene mountain glaciation in the western United States: Journal of Quaternary Science 23, 671-681. http://doi.org/10.1002/jqs.1210.

Thompson, R.S., Anderson, K.H., 2000. Biomes of western North America at 18,000, 6000, and 0 14C yr BP reconstructed from pollen and packrat midden data. Journal of Biogeography 27, 555-584. http://www.jstor.org/stable/2656210.

Thompson, R.S., Whitlock, C., Bartlein, P.J., Harrison, S.P., Spaulding, W.G., 1993. Climatic changes in the western United States since 18 000 yr B.P. In: H.E. Wright, Jr, J.E. Kutzbach, T. Webb III, W.F. Ruddiman, F.A. Street-Perrott, P.J. Bartlein (Eds.), Global climates since the last glacial maximum. University of Minnesota Press, Minneapolis, Minnesota, pp. 468-513.

Wagner, J. D., Cole, J. E., Beck, J. W., Patchett, P. J., Henderson, G. M., Barnett, H. R. 2010. Moisture variability in the southwestern United States linked to abrupt glacial climate change. Nature Geoscience 3, 110-113. http://doi.org/10.1038/NGEO707.

Ward, D. W., Anderson, R.S., Briner, J.P., Guido., Z.S. 2009. Numerical modeling of cosmogenic deglaciation records, Front Range and San Juan Mountains, Colorado. Journal of Geophysical Research–Earth Surface 114:F01026. http://doi.org/10.1029/2008JF001057.

Young, N.E., Briner, J.P., Leonard, E.M., Licciardi, J.M., Lee. K. 2011. Assessing climatic and non-climatic forcing of Pinedale glaciation and deglaciation in the western United States Geology 39, 171-174. http://doi.org/10.1130/G31527.1.

Yuan, F., Koran, M. R., Valdez, A. 2013. Late Glacial and Holocene record of climatic change in the southern Rocky Mountains from sediments in San Luis Lake, Colorado, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 392, 146-160. http://doi.org/10.1016/j.paleo2013.09.016.