Climatic Change

, Volume 26, Issue 2–3, pp 243–269

A warm and wet little climatic optimum and a cold and dry little ice age in the southern rocky mountains, U.S.A.

  • Kenneth Lee Petersen


The zenith of Anasazi Pueblo Indian occupation in the northern Colorado Plateau region of the southwestern U.S.A. coincides with the Little Climatic Optimum or Medieval Warm Period (A.D. 900–1300), and its demise coincides with the commencement of the Little Ice Age. Indexes of winter (jet-stream derived) and summer (monsoon derived) precipitation and growing season length were developed for the La Plata Mountains region of southwestern Colorado. The results show that during the height of the Little Climatic Optimum (A.D. 1000–1100) the region was characterized by a relatively long growing season and by a potential dry farming zone or elevational belt (currently located between 2,000 m and 2,300 m elevation) that was twice as wide as present and could support Anasazi upland dry farming down to at least 1,600 m, an elevation that is quite impossible to dry farm today because of insufficient soil moisture. This expanded dry-farm belt is attributable to a more vigorous circulation regime characterized by both greater winter and summer precipitation than that of today. Between A.D. 1100 and 1300 the potential dry-farm belt narrowed and finally disappeared with the onset of a period of markedly colder and drier conditions than currently exist. Finally, when the Little Ice Age terminated in the mid A.D. 1800s and warmer, wetter conditions returned to the region, another group of farmers (modern Anglos) were able to dry farm the area.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Barry, R. G. and Bradley, R. S.: 1976, ‘Historical Climatology’, in Steinhoff, H. W. and Ives, J. D. (eds.),Ecological Impacts of Snowpack Augmentation in the San Juan Mountains, Colorado, San Juan Ecology Project, Final Report, Colorado State University Publications, Fort Collins, pp. 43–47.Google Scholar
  2. Bray, J. R.: 1971, ‘Vegetationed Distribution, Tree Growth and Crop Success in Relation to Recent Climatic Change’, in Cragg, J. B. (ed.),Advances in Ecological Research 7, pp. 177–233.Google Scholar
  3. Betancourt, J. L.: 1984, ‘Late Quaternary Plant Zonation and Climate in Southeastern Utah’,Great Basin Natural. 44, 1–35.Google Scholar
  4. Berlin, G. L., Ambler, J. R., Hevly, R. H., and Shaber, G. G.: 1977, ‘Identification of a Sinagua Agricultural Field by Aerial Thermography, Soil Chemistry, Pollen/Plant Analysis, and Archaeology’,Amer. Antiq. 42, 588–600.Google Scholar
  5. Bradley, R. S. and Barry, R. G.: 1973, ‘Secular Climatic Fluctuations in Southwestern Colorado’,Month. Wea. Rev. 101, 264–270.Google Scholar
  6. Breternitz, D. A., Robinson, C. K., and Gross, G. T., (compilers): 1986,Dolores Archaeological Program: Final Synthetic Report, U.S. Department of Interior, Bureau of Reclamation, Engineering and Research Center, Denver.Google Scholar
  7. Brown, D. E. (ed.): 1982, ‘Biotic Communities of the American Southwest - United States and Mexico’,Desert Plants 4(1-4), 1-342.Google Scholar
  8. Bryson, R. A. and Julian, P. R. (conveners): 1963,Proceedings of the Conference on the Climate of the Eleventh and Sixteenth Centuries (Aspen, Colorado, June 16–24, 1962), NCAR Technical Notes 63-1, AFCRL-63-660, National Center for Atmospheric Research, Boulder, Colorado.Google Scholar
  9. Bryson, R. A. and Lowry, W. P.: 1955, ‘Synoptic Climatology of the Arizona Summer Precipitation Singularity’,Bull. Amer. Meteorol. Soc. 36, 329–339.Google Scholar
  10. Cordell, L. S.: 1984,Prehistory of the Southwest, Academic Press, Orlando, Florida.Google Scholar
  11. Damon, P. E., Ferguson, C. W., Long, A., and Wallick, E. I.: 1974, ‘Dendrochronologic Calibration of the Radiocarbon Time Scale’,Amer. Antiq. 39 (2 pt. 1), 350–366.Google Scholar
  12. Daubenmire, R. F.: 1943, ‘Soil Temperature versus Drought as a Factor Determining Lower Altitudinal Limits of Trees in the Rocky Mountain’,Botan. Gaz. 105, 1–13.Google Scholar
  13. Daubenmire, R. F.: 1954, ‘Alpine Timberlines in the Americas and Their Interpretation’,Butler Univ. Botan. Stud. 11, 119–136.Google Scholar
  14. Dean, J.S., Euler, R. C., Gumerman, G. J., Plog, F., Hevly, R. H., and Karlstom, T. H. V.: 1985, ‘Human Behavior, Demography, and the Paeoenvironment of the Colorado Plateaus’,Amer. Antiq. 50, 537–554.Google Scholar
  15. Dix, R. L. and Richards, J. L.: 1976, ‘Possible Changes in Spectra Structure of the Subalpine Forest Induces by Increased Snow Pack’, in Steinhoff, H. W. and Ives, J. D. (eds.),Ecological Impacts of Snowpack Augmentation in the San Juan Mountains, Colorado, San Juan Ecology Project, Final Report, Colorado State University Publications, Fort Collins, pp. 311–322.Google Scholar
  16. Dorrah, J. H., Jr.: 1946,Certain Hydrological and Climatic Characteristics of the Southwest, Publications in Engineering No. 1, University of New Mexico, Albuquerque.Google Scholar
  17. Drew, L. G. (ed.): 1974,Tree-Ring Chronologies of Western America: IV, Colorado, Utah, Nebraska, and South Dakota, Chronology Series 1, University of Arizona Laboratory of Tree-Ring Research, Tucson.Google Scholar
  18. Emerson, F. W.: 1932, ‘The Tension Zone Between the Grama Grass and Pinyon-Juniper Associations in Northeastern New Mexico’,Ecology 13, 347–358.Google Scholar
  19. Erdman, J. A.: 1970, ‘Pinyon-Juniper Succession after Natural Fires on Residual Soils of Mesa Verde, Colorado’,Brigham Young Univ. Sci. Bull., Biol. Ser. 11, 17–26.Google Scholar
  20. Erdman, J. A., Douglas, C. L., and Marr, J. W.: 1969,Wetherill Mesa Studies: Environment of Mesa Verde, Colorado, Archaeological Research No. 7B, U.S. Department of Interior, National Park Service, Washington, D.C.Google Scholar
  21. Euler, R. C., Gumerman, G. J., Karlstrom, T. N. V., Dean, J. S., and Hevly, H. R.: 1979, ‘The Colorado Plateaus: Cultural Dynamics and Paleoenvironment’,Science 205, 1089–1101.Google Scholar
  22. Farmer, E. E. and Fletcher, J. E.: 1971,Precipitation Characteristics of Summer Storms at High-Elevation Stations in Utah, Forest Service Research Paper INT-110, U.S. Department of Agriculture, Forest Service, Ogden.Google Scholar
  23. Fritts, H. C.: 1976,Tree Rings and Climate, Academic Press, New York.Google Scholar
  24. Fritts, H. C., Smith, D. G., and Stokes, M. A.; 1965, ‘The Biological Model for Paleoclimatic Interpretation of Mesa Verde Tree-Ring Series’, in Osborne, D. (assembler),Contributions of the Wetherill Mesa Archaeological Project, Society of American Archaeology Memoirs 19, Salt Lake City, pp. 101-121.Google Scholar
  25. Gregory, H. E. and Thorpe, M. R.: 1938,The San Juan Country: A Geographic and Geologic Reconnaissance of Southeastern Utah, Professional Paper 188, U.S. Geological Survey, U.S. Government Printing Office, Washington, D.C.Google Scholar
  26. Grove, J. M.: 1988,The Little Ice Age, Methuen, London.Google Scholar
  27. Gumerman, G. J. (ed.): 1988,The Anasazi in a Changing Environment, Cambridge University Press, New York.Google Scholar
  28. Heermann, D. F., Finkner, M. D., and Hiler, E. A.: 1971,Probability of Sequences of Wet and Dry Days for Eleven Western States and Texas, Experiment Station Technical Bulletin 117, Colorado State University, Fort Collins.Google Scholar
  29. Hevly, R. H.: 1981, ‘Pollen Production, Transport and Preservation: Potentials and Limitations in Archaeological Palynology’,J. Ethnobiol. 1, 39–54.Google Scholar
  30. Houghton, J. T., Jenkins, G. J., and Ephraums, J. J. (eds.): 1990,Climate Change: The IPCC Scientific Assessment, Cambridge University Press, Cambridge, U.K.Google Scholar
  31. Huntington, E.: 1914,The Climatic Factor as Illustrated in Arid America, Publication 192, Carnegie Institution of Washington, Washington, D.C.Google Scholar
  32. Jennings, J. D.: 1968,Prehistory of North America, McGraw-Hill, New York.Google Scholar
  33. King, J. E.: 1967, ‘Modern Pollen Rain and Fossil Pollen in Soils in the Sandia Mountains, New Mexico’,Papers Michig. Acad. Sci., Arts Lett. 52, 31–41.Google Scholar
  34. Klein, J., lerman, J. C., Damon, P. E., and Ralph, E. K.: 1982, ‘Calibration of Radiocarbon Dates: Tables Based on the Consensus Data of the Workshop on Calibrating the Radiocarbon Time Scale’,Radiocarbon 24, 103–150.Google Scholar
  35. LaMarche, V. C., Jr.: 1974, ‘Paleoclimatic Inferences from Long Tree-Ring Records’,Science 183, 1043–1048.Google Scholar
  36. LaMarche, V. C., Jr., and Stockton, C. W.: 1974, ‘Chronologies from Temperature Sensitive Bristlecone Pines at Upper Treeline in the Western United States’,Tree-Ring Bull. 34, 21–45.Google Scholar
  37. Lamb, H. H.: 1977,Climate: Present, Past and Future, Vol. 2, Climate History and the Future, Methuen, London, England.Google Scholar
  38. Maher, L. J., Jr.: 1963, ‘Pollen Analyses of Surface Materials from the Southern San Juan Mountains, Colorado’,Geol. Soc. Amer. Bull. 74, 1485–1504.Google Scholar
  39. Malaurie, J., Vasari, Y., Hyvarinen, H., Delibrias, G., and Labeyrie, J.: 1972, ‘Preliminary Remarks on Holocene Paleoclimates in the Regions of Thule and Inglefield Land, above A11 since the Beginning of Our Own Era’, in Vasari, Y., Hyvarinen, H., and Hicks, S. (eds.),Climate Changes in Arctic Areas during the Last Ten-Thousand Years: A Symposium Held at Oulanka and Kevo, 4–10 October 1971, Acta Universitatis Ouluensis, Series A, Scientiae Refum Naturalium No. 3, Geologica No. 1, University of Oulu, Oulu, Finland, pp. 105–133.Google Scholar
  40. Martin, P. S.: 1963,The Last 10,000 Years: A Fossil Pollen Record of the American Southwest, The University of Arizona Press, Tucson.Google Scholar
  41. Martin, P. S., and Byers, W.: 1965, ‘Pollen and Archaeology at Wetherill Mesa’, in Osborne, D. (assembler),Contributions of the Wetherill Mesa Archaeological Project, Society of American Archaeology Memoirs 19, Salt Lake City, pp. 101-121.Google Scholar
  42. Miller, J. F., Frederick, R. H., and Tracey, R. J.: 1973,Precipitation - Frequency Atlas of the Western United States, Volume III - Colorado: NOAA Atlas 2, U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, Silver Springs, Maryland.Google Scholar
  43. Mitchell, V. L.: 1976, ‘Regionalization of Climate in the Western United States’,J. Appl. Meteorol. 15, 920–927.Google Scholar
  44. Newberry, J. S.: 1876, ‘Geological Report’, in Macomb, J. N. (ed.),Report of the Exploring Expedition from Santa Fe, New Mexico, to the Junction of the Grand and Green Rivers of the great Colorado of the West, in 1859, under the Command of Capt. J. N. Macomb, Corps of Topographical Engineers (now Colonel of Engineers); with Geological Report by Prof. J. S. newberry, Geologist of the Expedition, Engineer Department, U.S. Army, Government Printing Office, Washington, D.C.Google Scholar
  45. Nichols, H.: 1975,Palynological and Paleoclimatic Study of the Late Quaternary Displacement of the Boreal Forest-Tundra Ecotone in Keewatin and Mackenzi, N.W.T., Canada, Occasional Paper 15, Institute of Arctic and Alpine Research, Boulder, Colorado.Google Scholar
  46. Osborne, D. (assembler): 1965,Contributions of the Wetherill Mesa Archaeological Project, Society of American Archaeology Memoirs 19, Salt Lake City.Google Scholar
  47. Patzelt, G.: 1974, ‘Holocene Variations of Glaciers in the Alps, inles Methodes Quantitative d'Etude des Variations du Climat au cours du Pleistocene, Gif-sur-Yvette, 5–9 juin 1973, Colloques Internationaux du Centre National de la Recherche Scientifique219, 51-59.Google Scholar
  48. Pearson, G. A.: 1931,Forest Types in the Southwest as Determined by Climate and Soil, Technical Bulletin 247, U.S. Department of Agriculture, U.S. Government Printing Office, Washington, D.C.Google Scholar
  49. Van Pelt, N. S.: 1978, ‘Woodland and Parks in Southeastern Utah’, unpublished Masters' Thesis, Department of Geography, University of Utah, Salt Lake City.Google Scholar
  50. Petersen, K. L.: 1984, ‘Man and Environment in the Dolores River Valley, S. W. Colorado: Some Pollen Evidence’, inAMQUA 1984, Program and Abstracts, Eighth Biennial Meeting, American Quaternary Association, University of Colorado, Boulder, p. 102.Google Scholar
  51. Petersen, K. L.: 1985, ‘Palynology in Montezuma County, Southwestern Colorado: The Local History of Pinyon Pine (Pinus edulis)’, in Jacobs, B., Davis, O., and Fall, P. (eds.),Late Quaternary Palynology of the American Southwest, ASSP Contribution Series 16, American Association of Stratigraphic Palynologists Foundation, Dallas, pp. 47–62.Google Scholar
  52. Petersen, K. L.: 1986, ‘Section 3: Pollen Studies: Temporal Patterns and Resource Uses’, in Petersen, K. L., Matthews, and Neusius, S. W., ‘Chapter 4 - Environmental Archaeology’, in Breternitz, D. A., Robinson, C. K., and Gross, G. T. (compilers),Dolores Archaeological Program: Final Synthetic Report, U.S. Department of Interior, Bureau of Reclamation, Engineering and Research Center, Denver, pp. 184–199.Google Scholar
  53. Petersen, K. L.: 1988a,Climate and the Dolores River Anasazi, University of Utah Anthrolopological Papers No. 113, University of Utah Press, Salt Lake City.Google Scholar
  54. Petersen, K. L.: 1988b, ‘Comparison of Modern Surface Pollen Samples with Samples from Sagehen Marsh, Dolores River Valley, Montezuma County, Southwestern Colorado’,AMQUA 1988, Program and Abstracts, Tenth Biennial Meeting, American Quaternary Association, University of Massachusetts, Amherst, p. 147.Google Scholar
  55. Petersen, K. L. and Mehringer, P. J., Jr.: 1976, ‘Postglacial Timberline Fluctuations, La Plata Mountains, Southwestern Colorado’,Arctic Alpine Res. 8, 275–288.Google Scholar
  56. Petersen, K. L., Clay, V. L., Matthews, M. H., Neusius, S. W. (compilers), and Breternitz, D. A. (principal investigator): 1985,Dolores Archeological Program: Studies in Environmental Archaeology, U.S. Department of Interior, Bureau of Reclamation, Engineering and Research Center, Denver.Google Scholar
  57. Petersen, K. L., Orcutt, J. D. (compilers), and Breternitz, D. A. (principal investigator): 1987,Dolores Archaeological Program: Supporting Studies: Settlement and Environment, U.S. Department of Interior, Bureau of Reclamation, Engineering and Research Center, Denver.Google Scholar
  58. Porter, S. C.: 1986, ‘Pattern and Forcing of Northern Hemisphere Glacier Variations during the Last Millennium’,Quatern. Res. 26, 27–48.Google Scholar
  59. Pyke, C. B.: 1972,Some Meteorological Aspects of the Seasonal Distribution of Precipitation in the Western United States and Baja California, Water Resources Center Contribution No. 139, University of California, Los Angeles.Google Scholar
  60. Samuels, M. L. and Betancourt, J. L.: 1982, ‘Modeling the Long-Term Effects of Fuelwood Harvest on Pinyon-Juniper Woodlands’,Environm. Managem. 6, 505–515.Google Scholar
  61. Schlanger, S. H.: 1988, ‘Patterns of Population Movement and Long Term Population Growth in Southwestern Colorado’,Amer. Antiq. 35, 773–793.Google Scholar
  62. Schneider, S. H.: 1986, ‘Can Modeling of the Ancient Past Verify Prediction of Future Climates? An Editorial’,Clim. Change 8, 117–119.Google Scholar
  63. Schoenwetter, J.: 1966, ‘A Re-Evaluation of the Navajo Reservoir Pollen Chronology’,El Palacio 73, 19–26.Google Scholar
  64. Schoenwetter, J.: 1967, ‘Pollen Survey of the Shiprock Area’, in Harris, A. H., Schoenwetter, J., and Warren, A. H.,An Archaeological Survey of the Chuska Valley Chaco Plateau, New Mexico. Part I: Natural Science Studies, Research Records 4, Museum of New Mexico, Albuquerque, pp. 72–103.Google Scholar
  65. Schoenwetter, J.: 1970, ‘Archaeological Pollen Studies of the Colorado Plateau’,Amer. Antiq. 35, 35–48.Google Scholar
  66. Schoenwetter, J. and Eddy, F. W.: 1964,Alluvial and Palynological Reconstruction of Environments, Navajo Reservoir District, Papers in Anthropology 13, Museum of New Mexico, Albuquerque.Google Scholar
  67. Schubert, G. H.: 1974,Silviculture of Southwestern Ponderosa Pine: The Status of Our Knowledge, Forest Service Research Paper RM-123, U.S. Department of Agriculture, Forest Service, Fort Collins.Google Scholar
  68. Scuderi, L. A.: 1990, ‘Tree-Ring Evidence for Climatically Effective Volcanic Eruptions’,Quatern. Res. 34, 67–85.Google Scholar
  69. Short, S. K. and Nichols, H.: 1977, ‘Holocene Pollen Diagrams from Subarctic Labrador-Ungava: Vegetational History and Climate Change’,Arctic Alpine Res. 9, 265–290.Google Scholar
  70. Smiley, T. L.: 1961, ‘Evidences of Climatic Fluctuations in Southwestern Prehistory’, in Fairbridge, R. W. (ed.),Solar Variations, Climatic Change, and Related Geophysical Problems, Annals of the New York Academy of Sciences 95(Art. 1), New York, pp. 697-704.Google Scholar
  71. Spencer, D. A.: 1964, ‘Porcupine Population Fluctuations in Past Centuries Revealed by Dendrochronology’,J. Appl. Ecol. 1, 127–159.Google Scholar
  72. Stockton, C. W.: 1976, ‘Long-Term Streamflow Reconstruction in the Upper Colorado River Basin using Tree Rings’, in Clyde, C. A., Falkenburg, P. H., and Riley, J. P. (eds.),Colorado River Basin Modeling Studies: Proceedings of a Seminar Held at Utah State University, College of Engineering, Logan, Utah, July 16–18, 1975, Utah Water Research Laboratory, Utah State University, pp. 401-441.Google Scholar
  73. Stuiver, M. and Reimer, P. J.: 1986, ‘A Computer Program for Radiocarbon Age Calibration’,Radiocarbon 28, 1022–1030.Google Scholar
  74. Thomas, H. E.: 1959, ‘Reservoirs to Match our Climatic Fluctuation’,Amer. Meteorol. Soc. Bull. 40, 240–249.Google Scholar
  75. Tranquillini, W.: 1979,Physiological Ecology of the Alpine Timberline: Tree Existence at High Altitudes with Special Reference to the European Alps, Springer-Berlag, BerlinGoogle Scholar
  76. U.S. Department of Agriculture, Soil Conservation Serive: 1976,Land Use and Natural Plant Communities, Montezuma County, Colorado, Map M7-0-23444-43, U.S. Department of Agriculture, Soil Conservation Service, Portland.Google Scholar
  77. Wallen C. C.: 1955, ‘Some Characteristics of Precipitation in Mexico’,Geograf. Annal. 37, 51–85.Google Scholar
  78. Wardle, P.: ‘1974, ‘Alpine Timberlines’, in Ives, J. D. and Barry, R. G. (eds.),Arctic and Alpine Environments, Methuen, London, pp. 371-402.Google Scholar
  79. Wells, P. V.: 1979, ‘An Equable Glaciopluvial in the West: Pleniglacial Evidence of Increased Precipitation on the Gradient from the Great Basin to the Sonoran and Chihuahuan Deserts’,Quatern. Res. 12, 311–325.Google Scholar
  80. Woodbury, R. W.: 1961, ‘Climatic Changes and Prehistoric Agriculture in the Southwestern United States’, in Fairbridge, R. W. (ed.),Solar Variations, Climatic Change, and Related Geophysical Problems, Annals of the New York Academy of Sciences 95(Art. 1), New York, pp. 697-704.Google Scholar
  81. Woosley, A. I.: 1977, ‘Farm Field Location through Palynology’, in Winters, J. C. (ed.),Hovenweep 1976, Archaeology Report No. 3, Anthropology Department, San Jose State University, San Jose, California, pp. 133–150.Google Scholar
  82. Wormington, H. M.: 1947,Prehistoric Indians of the Southwest, Popular Series 7, Denver Museum of Natural History, Denver.Google Scholar
  83. Wright, J. W.: 1952,Pollen Dispersion of Some Forest Trees, Northeastern Forest Experiment Station Paper 46, U.S. Department of Agriculture, Forest Service, Upper Darby, Pennsylvania.Google Scholar

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Kenneth Lee Petersen
    • 1
  1. 1.Westinghouse Hanford CompanyRichlandUSA

Personalised recommendations