Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-23T22:58:57.692Z Has data issue: false hasContentIssue false
  • English
  • Français

Changing Patterns in the Holocene Pollen Record of Northeastern North America: A Mapped Summary

Published online by Cambridge University Press:  20 January 2017

J. Christopher Bernabo  and
Thompson Webb III
J. Christopher Bernabo
Affiliation:
Department of Geological Sciences, Brown University, Providence, Rhode Island 02912 USA
Thompson Webb III
Affiliation:
Department of Geological Sciences, Brown University, Providence, Rhode Island 02912 USA
Get access Rights & Permissions [Opens in a new window]

Abstract

By mapping the data from 62 radiocarbon-dated pollen diagrams, this paper illustrates the Holocene history of four major vegetational regions in northeastern North America. Isopoll maps, difference maps, and isochrone maps are used in order to examine the changing patterns within the data set and to study broad-scale and long-term vegetational dynamics. Isopoll maps show the distributions of spruce (Picea), pine (Pinus), oak (Quercus), herb (nonarboreal pollen groups excluding Cyperaceae), and birch + maple + beech + hemlock (Betula, Acer, Fagus, Tsuga) pollen at specified times from 11,000 BP to present. Difference maps were constructed by subtracting successive isopoll maps and illustrate the changing patterns of pollen abundances from one time to the next. The isochrone maps portray the movement of ecotones and range limits by showing their positions at a sequence of times during the Holocene. After 11,000 BP, the broad region over which spruce pollen had dominated progressively shrank as the boreal forest zone was compressed between the retreating ice margin and the rapidly westward and northward expanding region where pine was the predominant pollen type. Simultaneously, the oak-pollen-dominated deciduous forest moved up from the south and the prairie expanded eastward. By 7000 BP, the prairie had attained its maximum eastward extent with the period of its most rapid expansion evident between 10,000 and 9000 BP. Many of the trends of the early Holocene were reversed after 7000 BP with the prairie retreating westward and the boreal and other zones edging southward. In the last 500 years, man's impact on the vegetation is clearly visible, especially in the greatly expanded region dominated by herb pollen. The large scale changes before 7000 BP probably reflect shifts in the macroclimatic patterns that were themselves being modified by the retreat and disintegration of the Laurentide ice sheet. Subsequent changes in the pollen and vegetation were less dramatic than those of the early Holocene.

Type
Research Article
Information
Quaternary Research , Volume 8 , Issue 1 , July 1977 , pp. 64 - 96
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bailey, R., (1969). Charles Lake. . (Unpublished data)..Google Scholar
Bailey, R., (1972). Late- and Postglacial Environmental Changes in Northeastern Indiana. Ph.D. Thesis. Indiana University. Google Scholar
Bailey , R., Wintergreen Lake. . (Unpublished data)..Google Scholar
Baker, R.G., (1970). A radiocarbon-dated pollen chronology for Wisconsin: Disterhaft Farm Bog revisited. Geological Society of America, Annual Meeting Abstracts. 2, 488.Google Scholar
Birks, H.J.B., (1976). Late-Wisconsinan vegetational history at Wolf Creek, central Minnesota. Ecological Monographs. 46, 395-429.Google Scholar
Birks, H.J.B., Saarnisto, M., (1975). Isopollen maps and principal components analyses of Finnish pollen data for 4,000, 7,000 and 8,000 years ago. Boreas. 4, 77-96.CrossRefGoogle Scholar
Birks, H.J.B., Deacon, J., Peglar, S., 1975a. Pollen maps for British Isles 5,000 years ago. Proceedings Royal Society of London B. 189, 87-105.Google Scholar
Birks, H.J.B., Webb, T. III, Berti, A.A., 1975b. Numerical analysis of pollen samples from Central Canada: A comparison of methods. Review of Palaeobotany and Palynology. 20, 133-169.Google Scholar
Bryson, R.A., (1966). Air masses, streamlines and the boreal forest. Geographical Bulletin. 8, 228-269.Google Scholar
Bryson, R.A., Wendland, W.M., Ives, J.D., Andrews, J.T., (1969). Radiocarbon isochrones on the disintegration of the Laurentide Ice Sheet. Arctic and Alpine Research. 1, 1-14.CrossRefGoogle Scholar
Bryson, R.A., Baerreis, D.A., Wendland, W.M., (1970). The character of late- and postglacial climatic changes. Dort, W., Jones, J.K., Pleistocene and Recent Environments of the Central Great Plains. Univ. of Kansas Press, Lawrence, 53-74.Google Scholar
Bryson, R.A., Kutzbach, J.E., (1974). On the analysis of pollen-climate canonical transfer functions. Quaternary Research. 4, 162-174.CrossRefGoogle Scholar
Brubaker, L.B., (1975). Postglacial forest patterns associated with till and outwash in northcentral upper Michigan. Quaternary Research. 5, 499-527.Google Scholar
1976. CLIMAP. The surface of the Ice-Age earth. Science, 191, 1131-1137.Google Scholar
Connally, G.G., Sirkin, L.A., (1971). Luzerne readvance near Glens Falls, New York. Geological Society of America Bulletin. 82, 989-1008.CrossRefGoogle Scholar
Craig, A.J., (1969). Vegetational history of the Shenandoah Valley, Virginia. Geological Society of America Special Papers. 123, 283-296.Google Scholar
Craig, A.J., (1972). Pollen influx to laminated sediments: A pollen diagram from northeastern Minnesota. Ecology. 53, 46-57.CrossRefGoogle Scholar
Cushing, E.J., (1965). Problems in the Quaternary phytogeography of the Great Lakes region. Wright, H.E. Jr., Frey, D.G., The Quaternary of the United States. Princeton Univ. Press, Princeton, N.J, 403-416.Google Scholar
Davis, A., (1975). Record of Local and Regional Holocene Environments from the Pollen and Peat Stratigraphies of Some Driftless Area Peat Deposits. Ph.D. Thesis. Univ. of Wisconsin, Madison. Google Scholar
Davis, M.B., (1965). Phytogeography and palynology of northeastern United States. Wright, H.E. Jr., Frey, D.G., The Quaternary of the United States. Princeton Univ. Press, Princeton, N.J, 377-401.Google Scholar
Davis, M.B., (1967). Late-glacial climate in northern United States: A comparison of New England and the Great Lakes region. Cushing, E.J., Wright, H.E. Jr., Quaternary Paleoecology. Yale Univ. Press, New Haven, 11-43.Google Scholar
Davis, M.B., (1968). Pollen grains in lake sediments: redeposition caused by seasonal water circulation. Science. 162, 796-799.CrossRefGoogle ScholarPubMed
Davis, M.B., (1969). Climatic changes in southern Connecticut recorded by pollen deposition at Rogers Lake. Ecology. 50, 409-422.CrossRefGoogle Scholar
Davis, M.B., (1974). Holocene migrations of ecotones: Continuing northward migration of tree species throughout the Holocene caused changes in community composition and migrations of ecotones. American Quaternary Association Abstracts of Third Biennial Meeting. 18-22.Google Scholar
Davis, M.B., (1976). Pleistocene biogeography of temperate deciduous forests. Geoscience and Man. 13, 13-26.Google Scholar
Davis, R.B., Webb, T. III, (1975). The contemporary distribution of pollen in eastern North America: a comparison with the vegetation. Quaternary Research. 5, 395-434.Google Scholar
Davis, R.B., Bradstreet, T.E., Stuckenrath, R. Jr., Borns, H.W. Jr., (1975). Vegetation and associated environments during the past 14,000 years near Moulton Pond, Maine. Quaternary Research. 5, 435-465.Google Scholar
Donner, J.J., (1963). The zoning of the postglacial pollen diagrams in Finland and the main changes in the forest composition. Acta Botanica Fennica. 65, 2-40.Google Scholar
Durkee, L.H., (1971). A pollen profile from Woden Bog, Hancock County, Iowa. Ecology. 52, 835-844.CrossRefGoogle Scholar
Elson, J.A., (1967). Geology of glacial Lake Agassiz. Mayer-Oakes, W.J., Life, Land and Water. Univ. of Manitoba Press, Winnipeg, 37-96.Google Scholar
Emery, K.O., Garrison, L.E., (1967). Sea levels 7,000 to 20,000 years ago. Science. 157, 684-687.Google Scholar
Faegri, K., Iversen, J., (1964) Textbook of Pollen Analysis. Hafner, New York. Google Scholar
Firbas, F., (1949). Spät-und nacheiszeitliche Waldegeschichte Mitteleuropas nördlich der Alpen. Verlag von Gustav Fischer, Jena. Google Scholar
Flint, R.F., (1971) Glacial and Pleistocene Geology. Wiley, New York. Google Scholar
Florer, L.E., (1972). Palynology of a post-glacial bog in the New Jersey Pine Barrens. Torrey Botanical Bulletin. 99, 135-138.Google Scholar
Frey, D.G., (1951). Pollen succession in the sediments of Singletary Lake, North Carolina. Ecology. 32, 518-533.Google Scholar
Fries, M., (1962). Pollen profiles of Late Pleistocene and recent sediments at Weber Lake, northeastern Minnesota. Ecology. 43, 295-308.CrossRefGoogle Scholar
Fritts, H.C., Blasing, T.J., Hayden, B.P., Kutzbach, J.E., (1971). Multivariate techniques for specifying tree-growth and climate relationships and for reconstructing anomalies in paleoclimate. Journal of Applied Meteorology. 10, 845-864.2.0.CO;2>CrossRefGoogle Scholar
Gilliam, J.A., Kapp, R.O., Bogue, R.D., (1967). A post-Wisconsin pollen sequence from Vestaburg Bog, Montcalm County, Michigan. Michigan Academy of Science, Arts and Letters. 52, 3-17.Google Scholar
Grant, D.R., (1970). Recent coastal submergence of the Maritime provinces, Canada. Canadian Journal of Earth Sciences. 7, 676-689.CrossRefGoogle Scholar
Grüger, J., üger, 1973. Studies on the late Quaternary vegetation history of northeastern Kansas. Geological Society of America Bulletin. 84, 239-250.2.0.CO;2>CrossRefGoogle Scholar
Halliday, W.E.D., Brown, A.W.A., (1943). The distribution of some important forest trees in Canada. Ecology. 24, 353-373.Google Scholar
Hare, K.F., (1973). On the climatology of post-Wisconsin events in Canada. Arctic and Alpine Research. 5, 169-170.Google Scholar
Hough, J.L., (1963). The prehistoric Great Lakes of North America. American Scientist. 5, 84-110.Google Scholar
Hughes, D.L., (1965). Surficial geology of part of the Cochrane District, Ontario, Canada. Geological Society of American Special Papers. 84, 535-565.Google Scholar
Imbrie, J., Kipp, N.G., (1971). A new micropaleontological method for quantitative paleoclimatology: Application to a late Pleistocene Caribbean core. Turekian, K., The Late Cenozoic Glacial Ages. Yale Univ. Press, New Haven, 71-181.Google Scholar
Janssen, C.R., (1968). Myrtle Lake: A late and postglacial pollen diagram from northern Minnesota. Canadian Journal of Botany. 46, 1397-1410.Google Scholar
Kapp, R.O., Bushouse, S., Foster, B., (1969). A contribution to the geology and forest history of Beaver Island, Michigan. Proceedings 12th Conference of Great Lakes Research. 225-236.Google Scholar
Karrow, P.F., (1963) Pleistocene Geology of the Hamilton-Galt Area. Ontario Department of Mines, Toronto, Geological Report 16.Google Scholar
Kerfoot, W.C., (1974). Net accumulation rates and the history of cladoceran communities. Ecology. 55, 51-61.Google Scholar
Kipp, N.G., (1976). A new transfer function for estimating past sea-surface conditions from the sea-bed distribution of planktonic foraminiferal assemblages in the North Atlantic. Geological Society of America Memoir. 145, 3-12.Google Scholar
LaMarche, 19.C. Jr., Fritts, H.C., (1971). Anomaly patterns of climate over western United States 1700–1930, derived from principal component analysis of tree-ring data. Monthly Weather Review. 99, 138-142.Google Scholar
Lasalle, P., (1966). Late Quaternary vegetation and glacial history in the St. Lawrence lowland, Canada. Leidse Geologische Mededelingen, Leiden. 38, 91-128.Google Scholar
Lawrenz, R., (1975). Biostratigraphic Study of Green Lake Michigan. M.S. Thesis. Central Michigan University. Google Scholar
Lee, H.A., (1960). Late-glacial and postglacial Hudson Bay sea episode. Science. 131, 1609.Google Scholar
Lichti-Federovich, S., Ritchie, J.C., (1968). Recent pollen assemblages from the western interior of Canada. Review of Palaeobotany and Palynology. 7, 297-344.Google Scholar
Likens, G.E., Davis, M.B., (1975). Postglacial history of Mirror Lake and its watershed in New Hampshire, U. S. A.: an initial report. Verhandlunger der Internationalen Vereinigung für theoretische und angewandte Limnologie. 19, 982-993.Google Scholar
Livingstone, D.A., (1958). Late-glacial and postglacial vegetation from Gillis Lake, Nova Scotia. American Journal of Science. 256, 341-359.Google Scholar
Livingstone, D.A., (1968). Some interstadial and postglacial pollen diagrams from eastern Canada. Ecological Monographs. 38, 87-125.CrossRefGoogle Scholar
Markgaf, 20., (1970). Paleohistory of spruce in Switzerland. Nature (London). 228, 249-251.Google Scholar
Maxwell, J.A., Davis, M.B., (1972). Pollen evidence of Pleistocene and Holocene vegetation on the Allegheny Plateau, Maryland. Quaternary Research. 2, 506-530.Google Scholar
McAndrews, J.H., (1966). Postglacial history of prairie, savanna and forest in northeastern Minnesota. Torrey Botanical Club Memoirs. 22, 1-72.Google Scholar
McAndrews, J.H., (1970). Fossil pollen and our changing landscape and climate. Rotunda. 3, 30-37.Google Scholar
McAndrews, J.H., Berti, A.A., Norris, G., (1973) Key to the Quaternary Pollen and Spores of the Great Lakes Region. Royal Ontario Museum, Life Sciences Miscellaneous Publication.CrossRefGoogle Scholar
McDowell, L.L., Dole, R.M. Jr., Howard, M., Farrington, R.A., (1971). Palynology and radiocarbon chronology of Bugbee Wildflower Sanctuary and Natural Area, Caledonia County, Vermont. Pollen et Spores. 13, 73-91.Google Scholar
McIntyre, A., Kipp, N.G., Bé, A.W.H., Crowley, T., Kellogg, T., Gardner, J., Prell, W., Ruddiman, W.F., (1976). The glacial North Atlantic 18,000 years ago: A CLIMAP reconstruction. Geological Society of America Memoir. 145, 43-76.Google Scholar
Miller, N.G., (1973) Late-Glacial and Postglacial Vegetation Change in Southwestern New York State. New York State Museum and Science Service Bulletin 420.CrossRefGoogle Scholar
Moe, D., (1970). The post-glacial immigration of Picea abies into Fennoscandia. Botaniska Notiser. 123, 61-66.Google Scholar
Moran, J.M., (1973). The late-glacial retreat of ‘Arctic’ air as suggested by onset of Picea decline. The Professional Geographer. 25, 373-376.CrossRefGoogle Scholar
Mott, R.J., (1975). Palynological studies of lake sediment profiles from southwestern New Brunswick. Canadian Journal of Earth Sciences. 12, 273-288.CrossRefGoogle Scholar
Mott, R.J., Camfield, M., (1969). Palynological Studies in the Ottawa area. Geological Survey of Canada Paper 69. .Google Scholar
Neustadt, M.I., (1959). Geschichte der vegetation der USSR im Holozän. Grana Palynologica. 2, 67-76.Google Scholar
Nicholas, J., (1968). Late Pleistocene Palynology of Southeastern New York and Northern New Jersey. Ph.D. Thesis. New York University. Google Scholar
Nichols, H., (1975) Palynological and Paleoclimatic Study of the Late Quaternary Displacement of the Boreal Forest-Tundra Ecotone in Keewatin and Mackenzie, N.W.T., Canada. Institute of Arctic and Alpine Research, Colorado, Occasional Paper No. 15.Google Scholar
Ogden, J.G. III, (1966). Forest history of Ohio, radiocarbon dates and pollen stratigraphy of silver Lake, Ohio. Ohio Journal of Science. 66, 387-400.Google Scholar
Odgen, J.G. III, (1969). Correlation of contemporary and late Pleistocene pollen records in the reconstruction of postglacial environments in northeastern North America. Mitteilungein Internationale Vereinigung Limnologie. 17, 661-677.Google Scholar
Prest, 21.K., (1969) Retreat of Wisconsin and Recent Ice in North Amrica. Geological Survey of Canada Map 1257A.Google Scholar
Prest, 22.K., (1970). Quaternary geology of Canada. Douglas, R.J.W., Geology and Economic Minerals of Canada. Geological Survey of Canada, Economic Geology Report 1. 676-764 Chap. 12.Google Scholar
Richard, P., (1970). Atlas pollinique des arbres et de quelque arbustes indigenes du Quebec: I, II, III, IV. Naturaliste Canadien. 97, 1-34.Google Scholar
Richard, P., Atlas pollinique des arbres et de quelque arbustes indigenes du Quebec: I, II, III, IV. Naturaliste Canadien. 97, 97-161.Google Scholar
Richard, P., Atlas pollinique des arbres et de quelque arbustes indigenes du Quebec: I, II, III, IV. Naturaliste Canadien. 97, 241-306.Google Scholar
Richard, P., (1971). Two pollen diagrams from the Quebec City area, Canada. Pollen et Spores. 13, 523-559.Google Scholar
Richard, P., 1973a. Historie postglaciaire de la vegetation dans la region de Saint-Raymond de Portneuf, telle que revelee par l'analyse pollinique d'une tourbiere. Naturaliste Canadien. 100, 561-575.Google Scholar
Richard, P., 1973b. Historie postglaciaire comparee de la vegetation dans deux localites au nord du Parc des Laurentides, Quebec. Naturaliste Canadien. 100, 577-590.Google Scholar
Richard, P., 1973c. Historie postglaciaire comparee de la vegetation dans deux localities au sud de la ville de Quebec. Naturaliste Canadien. 100, 591-603.Google Scholar
Ritchie, J.C., (1964). Contributions to the Holocene paleoecology of western Canada: I. The Riding Mountain area. Canadian Journal of Botany. 42, 181-196.Google Scholar
Ritchie, J.C., (1969). Absolute pollen frequencies and carbon-14 age of a section of Holocene lake sediment from the Riding Mountain area of Manitoba. Canadian Journal of Botany. 47, 1345-1349.Google Scholar
Ritchie, J.C., Lichti-Federovich, S., (1968). Holocene pollen assemblages from the Tiger Hills, Manitoba. Canadian Journal of Earch Sciences. 5, 873-880.Google Scholar
Ritchie, J.C., (1976). The late-Quaternary vegetational history of the western interior of Canada. Canadian Journal of Botany. 54, 1793-1818.Google Scholar
Saarnisto, M., (1974). The deglaciation history of the Lake Superior region and its climatic implications. Quaternary Research. 4, 316-339.Google Scholar
Saarnisto, M., (1975). Stratigraphic studies on the shoreline displacement of Lake Superior. Canadian Journal of Earth Sciences. 12, 300-319.Google Scholar
Serebryanny, L.R., (1973). Post-glacial migration rates of tree species in the northwestern regions of the USSR: palynology and radiocarbon dating. Khotinsky, N.A., Koreneva, E.23., Palynology: Holocene and Marine Palynology. Nauka, Moscow, 14-18 (in Russian).Google Scholar
Szafer, W., (1935). The significance of isopollen lines for the investigation of the geographical distribution of trees in the postglacial period. Polska Akademia Umiejetnosci. Wydzial Matematycznoprzyodicy. Bulletin International, S. B.. 235-239.Google Scholar
Terasmae, J., (1959). Notes on the Champlain sea episode in the St. Lawrence lowlands, Quebec. Science. 130, 334-335.Google Scholar
Terasmae, J., (1967). Postglacial chronology and forest history in the northern Lake Huron and Lake Superior regions. Cushing, E.J., Wright, H.E. Jr., Quaternary Paleoecology. Yale Univ. Press, New Haven, 45-48.Google Scholar
Terasmae, J., (1968). A discussion of deglaciation and the boreal forest in the northern Great Lakes region. Proceedings Entomological Society of Ontario. 99, 31-43.Google Scholar
Terasmae, J., (1973). Notes on late Wisconsin and early Holocene history of vegetation in Canada. Arctic and Alpine Research. 5, 201-222.Google Scholar
Vincent, J.-S., (1973). A palynological study for the Little Clay Belt, northwestern Quebec. Naturaliste Canadien. 100, 59-69.Google Scholar
Waddington, J.C.B., (1969). A stratigraphic record of the pollen influx to a Lake in the Big Woods of Minnesota. Geological Society of America Special Papers. 123, 263-281.Google Scholar
Walker, P.C., Hartman, R.I., (1960). The forest sequence of the Hartstown Bog area in western Pennsylvania. Ecology. 41, 461-474.Google Scholar
Watts, W.A., (1967). Late-glacial plant macrofossils from Minnesota. Cushing, E.J., Wright, H.E. Jr., Quaternary Paleoecology. Yale Univ. Press, New Haven, 89-98.Google Scholar
Watts, W.A., (1973). Rates of change and stability in vegetation in the perspective of long periods of time. Birks, H.J.B., West, R.G., Quaternary Plant Ecology. Blackwell, Oxford, 195-206.Google Scholar
Watts, W.A., Bright, R.C., (1968). Pollen, seed, and mollusk analysis of a sediment core from Pickerel Lake, northeastern South Dakota. Geological Society of America Bulletin. 79, 855-879.Google Scholar
Webb, T. III, (1973). A comparison of modern and presettlement pollen from southern Michigan, U. S. A.. Review of Palaeobotany and Palynology. 16, 137-156.Google Scholar
Webb, T. III, 1974a. Corresponding patterns of pollen and vegetation in lower Michigan: a comprison of quantitative data. Ecology. 55, 17-28.Google Scholar
Webb, T. III, 1974b. A vegetational history from northern Wisconsin: evidence from modern and fossil pollen. American Midland Naturalist. 92, 12-34.Google Scholar
Webb, T. III, Bernabo, J.C., (1974). Palynological evidence of ecotonal migrations in eastern North America. American Quaternary Association Abstracts of the Third Biennial Meeting. Vol. 26.Google Scholar
Webb, T. III, Bryson, R.A., (1972). Late- and postglacial climatic change in the northern Midwest, U. S. A.: Quantitative estimates derived from fossil pollen spectra by multivariate statistical analysis. Quaternary Research. 2, 70-115.Google Scholar
Webb, T. III, Clark, D.R., (1976). Calibrating micropaleontological data in climatic terms: A critical review. Annals New York Academy of Sciences. 288, 93-118.Google Scholar
Webb, T. III, McAndrews, J.H., (1976). Corresponding patterns of contemporary pollen and vegetation in central North America. Geological Society of America Memoir. 145, 267-302.Google Scholar
Webb , T. III, and Yeracaris , G. Y., (to appear).Comparison of patterns in pollen data from southeastern Canada and northeastern United States. In “Proceedings of the International Palynological Congress, Lucknow.”. .Google Scholar
West, R.G., (1961). Late and postglacial vegetational history in Wisconsin, particularly changes associated with the Valders readvance. American Journal of Science. 259, 766-783.Google Scholar
Whitehead, D.R., (1965). Palynology and Pleistocene phytogeography of unglaciated eastern North America. Wright, H.E. Jr., Frey, D.G., The Quaternary of the United States. Princeton Univ. Press, Princeton, N.J, 417-432.Google Scholar
Whitehead , D. R., (in preparation).Late-glacial and post-glacial vegetational history of the Berkshires. , western Massachusetts. .Google Scholar
Wright, H.E. Jr., 1968a. History of the Prairie Peninsula. Bergstrom, R.E., The Quaternary of Illinois. Special Report 14. College of Agriculture, University of Illinois, Urbana, 78-88.Google Scholar
Wright, H.E. Jr., 1968b. The roles of pine and spruce in the forest history of Minnesota and adjacent areas. Ecology. 49, 937-955.Google Scholar
Wright, H.E. Jr., (1971). Late Quaternary vegetation history of North America. Turekian, K., The Late Cenozoic Glacial Ages. Yale Univ. Press, New Haven, 425-464.Google Scholar
Wright, H.E. Jr., Patten, H.L., (1963). The pollen sum. Pollen et Spores. 5, 526-528.Google Scholar
Wright, H.E. Jr., Watts, W.A., (1969). Glacial and vegetational history of northeastern Minnesota. Minnesota Geological Survey. SP-11.Google Scholar
Wright, H.E. Jr., Winter, T.C., Patten, H.L., (1963). Two pollen diagrams from southeastern Minnesota: Problems in the late- and postglacial vegetational history. Geological Society of America Bulletin. 74, 1371-1396.Google Scholar
van Zeist, W., Wright, H.E. Jr., (1967). Über probleme der vegetation und pollenanalyse in Minnesota und angrezenden gebieten (U. S. A.). Tuxen, R., Pflanzenzoziologie und Palynologie. Verlag Dr. W. Junk, Den Haag, 121-133.Google Scholar