Origin of Lakes

I. General background
    A. There are a few large lakes, but ponds dominate numerically (85%)
    B. Lake districts

    C. Necessity of positive water balance

            Precipitation + Inflow > Evaporation + Outflow

    C. Processes in lake formation
        1. Constructive
        2. Destructive
        3. Obstructive

    D. Significance of lake formation

         1. Hydrology
                Including renewal time

         2. Basin shape
         3. Chemistry
         4. Trophic state
                a. eutrophic
                b. mesotrophic
                c. oligotrophic
                d. dystrophic
          5. Paleolimnology
          6. Endemic species
                relict lakes
                      Lake Baikal, Russia
                      Lake Tanganyika, Tanzania

TYPES OF LAKES

1. TECTONIC BASINS
        A. New land lakes
            1. uplifting of marine sediments
            2. often large and shallow
                   Lake Okeechobee, Florida

        B.  Structural basins
            1. Grabens
                a. lake in a downfaulted depression
                b. often long, narrow and deep

               Lake Baikal, Lake Tanganyika, Lake Tahoe, Pyramid Lake (Nevada),
                Lake Ohrid (Yugoslavia), Dead Sea, Lake Kinneret (Sea of Galilee)

            2. Tilted fault blocks
                    a. Fault on only one side

                           Abert Lake, Oregon

            3. Reverse drainage basins
                a. Uplifting forms a dam
                b. Dendritic lake

                  Lake Kioga, Uganda

            4. Upwarping
                    a. Uplifting around entire basin
                    b. Large but fairly shallow lake

                 Lake Victoria, East Africa

            5. Subsidence
                Local depression due to earthquakes

                New Madrid Quakes, Reelfoot Lake

2. LAKES ASSOCIATED WITH VOLCANIC ACTIVITY
        A. Craters in cinder cones

        B. Calderas
                1. collapsed or exploded volcanoes
                2. surrounded by rim of lava; deep
                3. oligotrophic

                    Crater Lake, OR (608 m deep)
                    Tagus Lake, Galapagos

        C. Maars
                1. explosion craters
                2. often small, round and not as deep as calderas

                    Eifel lake district (Black Forest of Germany)

        D. Lava flow lakes
            collapsed lava flow cavern

        E. Volcanic damming
            lava or ash dams a stream

             Lake Kivu, central Africa

3. LAKES FORMED BY LANDSLIDES
        · landslides block a river or stream
        · often short-lived lakes

                Quake Lake, Yellowstone

4. LAKES FORMED BY WIND
            A. deflation basins
                1. pan lakes (animals remove cover and trample; wind blows away dirt)
                2. playas (wind erosion in arid basins)
                3. often shallow and large

            B. sand dune lakes

5. LAKES FORMED BY RIVERS
            A. plunge pools
                includes basins of old waterfalls in now dry river systems
                    Falls Lake, WA (from ice break on glacial Lake Missoula in Grand Coulee region of WA)

            B. oxbow lakes
                1. bends in river that become isolated
                2. shallow and oddly shaped
                3. often interesting organisms in these lakes 

            C. floodplain or varzea lakes
                1. some are in depressions in the flood plain area
                2. some are due to sediments deposited across mouths of inflowing streams

6. LAKES FORMED BY GLACIERS AND ICE
            A. Existing glaciers or ice
                1. pockets of meltwater on the surface of or below glaciers
                2. lakes at the front of a receding glacier
                    a. irregularly shaped
                    b. silty
                3. glacier dams a valley
                4. permafrost lakes (cryogenic lakes)

            B. Past glaciers
                1. fjords
                    a. glacially deepened valley or fault adjoining the sea
                    b. may be isolated from the sea
                    c. may be dammed

                2. glacial carved basins
                    a. ice scour lakes (piedmont lakes)

                        (1) often on originally flat rock (not in mountains)
                        (2) lake basin on rock – may have poor drainage

                       many Canadian lakes (including Great Slave Lake)
                       Laurentian Great Lakes (scour and rebound)

                    b. cirque lakes
                        (1) common on formerly glaciated mountains
                        (2) small, round, steep sided (amphitheater-shaped)
                        (3) small drainage area
                        (4) reduced number of species
                        (5) paternoster lakes – series of cirques down a hill

                3. moraine lakes
                    a. material pushed by glaciers leaves dams of rock and dirt as the glacier retreats

                    Finger Lakes
                    Lake Mendota, WI

                4. kettle lakes
                    a. depressions in glacial till
                    b. sometimes due to melting ice block, sometimes irregularities in the moraine
                    c. irregularly shaped

                        Walden Pond
                         Linsley Pond

7. SOLUTION LAKES
        A. Formed by dissolution of soluble rock (often limestone) by percolating water
 

e.g., CaCO3 + CO2 + H2O <--> Ca2+ + 2HCO3-


       B. Areas with numerous solution lakes are known as 'Karst topography'
       C. sink holes – may form quickly and be short-lived (dolines)
       D. cave ponds and mound springs - often have strange and unique biota

8. LAKES ASSOCIATED WITH SHORELINES on shores of oceans and large lakes
    A. deltaic lakes – sedimentation as river currents slow when they enter a large lake or the ocean – may isolate lakes on deltas
    B. coastal lake -- movement of sand in spits and bars may enclose basins
 

9. LAKES FORMED BY METEOR IMPACT
    A. Can be very large
    B. Perfectly round

    Chubb Crater, Canada; 3.4 km diameter; 1.4 million years old

10. BIOGENIC LAKES
       A. buffalo wallows
       B. beaver ponds
       C. coral reefs
       D. bog lakes

       E. HUMAN MADE LAKES
            1. dams -- >40,000 reservoirs with dams over 15 m high; 60,000 with >0.1 km3 surface area;
                            10% of the volume of natural lakes
            2. borrow pits
            3. surface mine lakes
            4. bomb craters
 
 
 

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