Simplified Surficial Geology of Maine, Maine Geological Survey by bfk20410


									Simplified Surficial Geologic                                                                                              Recent stream alluvium, including flood
                                                                                                                           plain, stream terrace, and alluvial fan deposits.
                                                                                                                                                                                                                                     What will you find if you dig a hole?
       Map of Maine                                                         Fort Kent
                                                                                                                                                                                                          This cross section shows common relationships of glacial and postglacial surficial sediments
                                                                                                                                                                                                                            in valleys above (left) and below (right) the marine limit.
                                                                                                                           Recent swamp, marsh, and bog deposits
      DEPARTMENT OF CONSERV      ATION                                                                                                                                                                          Former glacial                                             Upper limit of late-glacial
          Maine Geological Survey                                                                                                                                                                               lake level                                                 marine submergence
                                                                                                                           Glacial lake-bottom deposits
   Modified from Thompson, W. B.,                                                                                                                                                            2        8
                                                                                                                                                                                                                   3             8
          and Borns, H. W., Jr.                                                                                            Glacial stream deposits and glacial-lake deltas.                                                                       1                                    6         10
   Surficial Geologic Map of Maine,                                                                                                                                                                                                   2                      2                                                     4
                                                                                                                                                                                                            2                                                                                                                     2
    1985, Maine Geological Survey                                                                                                                                                                1                         7                                                      5
                                                                                                                                                                                                                                                                                                          3                           1
                                                                                         Presque                           Glacial-marine deposits (silt and clay)
        Digital cartography by                                                           Isle
            Marc Loiselle                                                                                                                                                                     1- Bedrock                                                          6- Marine sand plain
                                                                                                                                                                                              2- Till                                                             7- Fine-grained glacial lake-bottom sediments
                                                                                                                           Glacial-marine deposits (sand and gravel)
         Robert G. Marvinney                                                                                                                                                                  3- Esker                                                            8- Glacial-lake delta
           State Geologist                                                                                                                                                                    4- Glacial-marine delta                                             9- Postglacial stream-terrace
                                                                                                                           Eskers                                                             5- Glacial-marine clay (Presumpscot Formation)                     10- Modern flood-plain
                                                             Mt. Katahdin                                                  Till                                                                                                                          Glacial Recession in Southern Maine

                                                                                                                           Bedrock and thin glacial sediment cover
                                                                                                                           Marine limit

                                                                    Millinocket                                                                                                                              New                                                                     Ice                  DS
                                                                                                                                                                                                                                      16,000 years ago
                                                                                                                                                                                                                                      a continental glacier                                                    D                          T

                                                Greenville                                                                                                                        MAINE                                               covered most of Maine,
                                                                                                                                                                                                                                      but was receding from the
                                                                                                                                                                                                                       Nova           coastal lowland. The sea was              EM
                                                                                                                  Calais                             Vermont                                                           Scotia         in contact with the ice margin.                       EM

                                                                                                                                                              New                                                                                                                      Ice
          Rangeley                                                                                                         Eastport
                                                                                                                                       New York             Hampshire                                                                                                                                         DR
                                                                                                                                                                               Maximum extent of glacial ice                                            T
                                                                                                                                                                                                                                                                         Ice E
                                                                                Bangor                                                                                         (about 28,000 to 24,000 years ago)
                                                                                                                                                             Mass.                                                                                                                         IB
                                                                                                                                                       Conn.     R.I.                                                                                                                           DS                                        T
                                                                                                                                                                                                                                      15,000 years ago,           ML
                                                                                                                                                                                                                                      the glacier was receding
                                                                                                                                       N.J.                                                                                           rapidly and southern Maine                                                              S
                                                                                                                                                                                                                                      was ice-free. The land was still                                                    M
                                                                                                                                                     exposed continental shelf                                                        depressed from the weight of                         BEM
                                      Augusta                                                Mount Desert                                                                                                                             the ice, resulting in extensive
                                                                                               Island                                                                                                                                 submergence of lowland areas.
                                                                                                                                                                                                     Atlantic Ocean
                                                                                                                                                                                                                                                                            K              K
                                                                     Penobscot Bay                                                    The color map (at left) shows the principal types of sedimentary materials that
                                                                                                                                                                                                                                                                                  OP                                     BR
                                                                                                                                      cover the bedrock in Maine. Most of these materials were left by glacial ice during
                                                                                                                                      the Pleistocene "ice age". One of Maine's distinctive glacial legacies is the blanket           13,000 years ago, the                                          D
                                                                                                                                      of marine sediments across southern portions of the state. The last continental ice             glacier had disappeared
                       Portland                                                                                                       sheet was so thick and heavy that it depressed the Earth's bedrock crust several                from central and southern
                                                                                                                                      hundred feet. Even though global sea level was lower in glacial times, this                     Maine. Uplift of the land had        M
                                  Casco Bay                                                                                                                                                                                                                                      EM
                                                                                                                                      depression enabled the sea to flood low areas of southern Maine as the glacier                  caused the sea to retreat.                                                          M
                                                                                                                                      receded. The dark-blue line on the map shows the inland limit of marine                                                                           BEM
                                                                                                                                      submergence. Numerous islands existed in the flooded area but are not shown
                                                                                                                                      here. The recession of the ice sheet caused the land to rise above the ocean, and a             BEM - buried end moraine           E - esker                                     ML - marine limit
                                                                                                                                      wide variety of sedimentary deposits were released from the melting glacier. These              BR - bedrock ridge                 EM - end moraine                              OP - outwash plain
                                                                                                                                      include long esker ridges of sand and gravel formed in tunnels under the ice, shown             D   - delta                        IB - ice block                                S - seawater
                                                                                                                                      by the red lines on the map. Maine's eskers and emerged marine features are world-              DR - drumlins                      K - kettle                                    T - till
      Kittery                                                                                                                         class examples of glacial deposits.                                                             DS - distributary stream           M - marine sediments

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