Lake Types

Scientists have long appreciated that a lake's physics, chemistry, and biological potential are predictable end products of its origin. In fact, trained scientists can infer much about a lake's current limnology by simply knowing its originating process. In the following paragraphs, 22 specific processes that originate distinct types of lake basins are enumerated and described. They are organized and presented by a principal environmental force as summarized in Table 2. Organic

Table 1 Estimates of the global number and aerial expanse of lakes greater than 0.01 km2 in surface area organized by principal environmental force

Principal

Number

Percent

Total

Percent

force

of lakes

of total

lake

of total

lakes

area

lake

(km2)

area

Glacial

3 875 000

74

1 247 000

50

Tectonic

249 000

5

893 000

35

Fluvial

531 000

10

218 000

9

Volcanic

1000

<1

3000

<1

Coastal

41 000

<1

60 000

2

Miscellaneous

567 000

10

88 000

4

Total

5 264 000

~100

2 509 000

100

A more recent study estimates that the Earth presently holds approximately 27 million natural lakes that are greater than 0.01 km2 in surface area, about five times more than the total number of lakes shown here. In addition, it is estimated that the Earth presently holds 277 million smaller natural lakes between 0.001 and 0.01 km2 in surface area, and 0.5 million reservoirs. Adapted from Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc.

A more recent study estimates that the Earth presently holds approximately 27 million natural lakes that are greater than 0.01 km2 in surface area, about five times more than the total number of lakes shown here. In addition, it is estimated that the Earth presently holds 277 million smaller natural lakes between 0.001 and 0.01 km2 in surface area, and 0.5 million reservoirs. Adapted from Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc.

accumulation is the only principal environmental force discussed by G. E. Hutchinson in his A Treatise on Limnology that is not considered here.

Glacial

Glaciers transform the Earth's surface through a variety of erosive and depositional processes resulting from their sheer physical constitution, their forward motion (advance), and their recession through melting (retreat). Glaciers form through the compaction and transformation of snow and other precipitation. During the Pleistocene, glaciers reached heights of 2 km above the Earth's surface, establishing enormous weight loads on the landscape. Under gravitational force imposed by their own mass, glaciers creep internally and slide along terrain, aided by, but not requiring, relief in the landscape. Rock debris is commonly incorporated into glacial ice through abrasion and quarrying (plucking) at the basal surface. Liquid water developing on or in glaciers is heavier than ice and tends to sink and layer along the glacial sole. This lubrication further aids their advance and erosive action.

Ice scour Ice scour lake basins are excavations in bedrock caused by the crushing and removal of loose debris. The depressions are generally carved during glacial advance, and deepened over cycles of retreat and readvance. In addition to the scouring effect of pure glacial ice, erosion is facilitated by protruding rock debris and melt water issuing through basal channels. Notable lakes with significant ice scouring in their origins include the Laurentian Great Lakes (Canada, USA), Great Bear Lake and Great Slave Lake (Canada), the fjord lakes in Norway, several lakes in the English Lake District (Figure 1), Lago Maggiore (Italy), Lac Leman (France, Switzerland), Lake Te Anau (New Zealand), and innumerable small lakes carved in the pre-Cambrian shield in Canada and Europe.

Glaciers tend to preferentially exploit weaknesses in rock structure and composition. As a result, the basin shorelines and subsurface contours of ice scour lakes often follow preexisting fracture and transitional zones in the bedrock. An acute example of bedrock control on scouring activity is provided by a set of lakes in Minnesota (USA) where glaciers excavated basins in soft slate layered between resistant columns of diabase sill (Figure 2). Quite impressive is that the long axes of these lake basins lie oblique to the southerly direction of glacial advance.

A stunning type of ice scour lake basin called a cirque (tarn) originates at the snow line in mountainous relief. Cirque basins derive from

Table 2 Common types of lake basins organized by principal environmental force

Principal force

Lake type

Process of basin origination

Glacial

Ice scour

D - Glacier excavates a depression.

Moraine dam

C - Glacier pushes or deposits terrain to make a rim.

Kettle

D - Stagnant glacier block displaces soil to make a depression.

Ice dam

O - Lobe or wall of glacier prevents drainage.

Ice basin

D,O - Depression or cavity in glacier prevents drainage.

Thaw

O,C - Permafrost prevents drainage and soils heave to make a rim.

Tectonic

Fault block

D,C - Fracture, faulting and warping define a depression and rim.

Reverse drainage

O - Uplift and tilting redirect drainage.

Newland

C - Uplift of ocean floor exposes a submarine depression.

Volcanic

Volcanic crater

D - Magma chamber empties to define a depression.

Volcanic dam

O - Volcano or cooled lava barricades a flow.

Fluvial

Plunge pool

D - Waterfall excavates a depression.

Oxbow

D,O - Coupled erosion and deposition close a river segment.

Fluvial dam

O - Fluvial sediments barricade a flow.

Organism behavior

Beaver pond

O - Wood and mud barricade a flow.

Reservoir

O - Human-constructed dam barricades a flow.

Farm pond, Mine pit

D - Human excavates a depression.

Chemical

Solution

D - Bedrock dissolves to make a depression.

Wind

Deflation

D - Wind excavates a depression.

Landslide

Landslide dam

O - Gravity moves terrain which barricades a flow.

Shoreline

Coastal

C - Sediments deposited from longshore currents close a bay.

Meteorite

Meteorite crater

D - Meteorite impact excavates a depression.

The terrain-shaping process at origination is coded as destructive (D), constructive (C), or obstructive (O).

The terrain-shaping process at origination is coded as destructive (D), constructive (C), or obstructive (O).

relatively small glaciers and are characteristically bowl-shaped and bounded on the upslope shore by a steep headwall of rock. The erosive power of freezing and thawing on a seasonal basis is believed to enhance local corrosion of the basin floor and walls.

Moraine dam Advancing glaciers push terrain at their leading edge whereas retreating glaciers deposit previously held debris as they melt. Both processes erect mounds of rock and soil on the landscape loosely referred to as moraines. Moraine dam lakes commonly reside in former river valleys with the moraine serving as a rim to complete the basin. Examples include Lake Mendota in Wisconsin and Mille Lacs Lake in Minnesota (USA), the latter lake being almost half bounded by moraine deposits (Figure 3). Ice scour and moraine building processes regularly labor in concert to forge glacial lake basins. As a result, many cirque lakes are impounded by a moraine at their downslope edge, and a vast number of lake basins categorized as ice scour depend to some degree on moraine rims to maintain their current depths. The Finger Lakes in New York (USA) were joint products of ice scour and moraine building processes.

Kettle Advancing and retreating glaciers commonly fracture and strand ice blocks. Ice blocks that become partially or fully buried in soil or in the sediment of an outwash plain can originate kettle lake basins

(Figure 4). In this process, the dimensions and extent of inlay of the ice strongly dictate the lake basin's shape and bathymetry. Kettle lakes are characteristically deep relative to surface area and they can be multibasined where two or more blocks of ice strand adjacent to one another. Kettle lakes abound in North America, Europe, and Asia. Lakes in the prairie pothole region in Canada and the lakes surveyed by pioneering limnologists Edward A. Birge and Chancey Juday in Wisconsin (USA) are primarily kettles.

Ice dam When glaciers themselves represent barricades that obstruct water flow they originate ice dam lakes. In regions of notable relief, an ice dam lake typically occurs where the lobe of a glacier extends down a main valley to barricade a tributary river entering from a lateral valley. The Marjelensee (Switzerland) is a well-known example. The basins of these lakes are highly transitory and can drain in a marked fashion if the dam hemorrhages. Lake Missoula (USA) was an ice dam lake of the Clark Fork River that once grew to a depth exceeding 600 m and covered an area the combined size of current day Lake Ontario and Lake Erie (Canada, USA). Scientists estimate that the lake drained within a week after the ice dam ruptured. Ice dam lakes also form on flatter terrain when the edge of a glacier prevents the drainage of its own melt water. Here the lake forms through ponding in front of the glacier

North America -.V

North America -.V

Minnesota (USA)

Horizontal scale below

Vertical scale below exaggerated 2.5 times

Clear water Lake

EAST

Caribou Rocky

Lake Lake

Alder Lake

Crocodile Lake

Vertical scale below exaggerated 2.5 times

Clear water Lake

EAST

Caribou Rocky

Lake Lake

Alder Lake

Crocodile Lake

Rove slate

Logan diabase sills WEST

Figure 2 Examples of some ice scour lakes in Minnesota (USA) that were carved in slate (metamorphic rock) resting between diabase sill (igneous rock). Adapted from Zumberge JH (1952) The Lakes of Minnesota: Their Origin and Classification, University of Minnesota Geological Survey Bulletin 35. Minneapolis: University of Minnesota. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

Rove slate

Logan diabase sills WEST

Duluth gabbro

Figure 2 Examples of some ice scour lakes in Minnesota (USA) that were carved in slate (metamorphic rock) resting between diabase sill (igneous rock). Adapted from Zumberge JH (1952) The Lakes of Minnesota: Their Origin and Classification, University of Minnesota Geological Survey Bulletin 35. Minneapolis: University of Minnesota. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

and is more specifically termed a proglacial lake. Isostatic rebound of the recently uncovered terrain may tilt it toward the glacier and enhance the ponding effect. Lake Agassiz, the largest proglacial lake known, existed for some 4000 years and covered more than 350 000 km2 during its life (Figure 5). The lake changed its configuration and reach many times as the glacier retreated northward. Vestiges of Lake Agassiz include Lake of the Woods (Canada, USA) and Lake Winnipeg (Canada).

Ice basin Ice basin lakes reside either on or in a glacier. They originate when melt water, obstructed from exiting a glacier, pools either in a surface depression or internally in a glacial cavity. The depressions and cavities form as a result of glacial movement, fracture, fluvial erosion, and heat from the sun and the Earth. In the case of surface depressions, the entire lake is cupped in a basin of ice. In the case of internal cavities, the lake basin commonly resides at the floor of the glacier and is bounded by land underneath and by ice on the walls and ceiling. Lake Vostok (Antarctica) is an example of the latter, residing some 4000 m below the central Antarctic ice sheet see Antarctica. It is a huge lake with a liquid depth of at least 800 m and an area comparable to modern day Lake Ontario (Canada, USA).

Thaw Thaw (thermokarst, cryogenic) lakes have fascinated scientists for decades. These lakes cover vast coastal areas in the arctic regions of Eurasia and North America. They are best classified as

Figure 3 An example of a moraine dam lake in Minnesota (USA). The stippled area shows moraine complex. Geographic reference as in Figure 2. Adapted from Zumberge JH (1952) The Lakes of Minnesota: Their Origin and Classification, University of Minnesota Geological Survey Bulletin 35. Minneapolis: University of Minnesota. Reprinted by permission.

Figure 3 An example of a moraine dam lake in Minnesota (USA). The stippled area shows moraine complex. Geographic reference as in Figure 2. Adapted from Zumberge JH (1952) The Lakes of Minnesota: Their Origin and Classification, University of Minnesota Geological Survey Bulletin 35. Minneapolis: University of Minnesota. Reprinted by permission.

periglacial because their origins depend on near-glacial conditions, but not glaciers themselves. A thaw lake originates when melt water in the surface layer of permafrost is prevented from draining downward by a deeper layer of frozen permafrost which serves as the basin floor. The surface area of a thaw lake may be quite small at first and polygon shaped. The soil rims that contain these lakes arise above fracture zones in the permafrost where annual freeze-thaw cycles lead to vertical expansion and soil upheaval. Contiguous thaw lakes will coalesce, resulting in large and small lakes in the same general area (Figure 6).

Tectonic

The Earth's exterior layer is comprised of a network of about a dozen relatively rigid, crustal plates that form a shell around the planet. The boundaries of these plates are zones of active slip, collision, and separation that generate what are called tectonic forces. Tectonic forces that translate upward to the

Earth's surface deform bedrock through fracture, rifting (separation), and warping (uplift and subsidence), resulting in the formation of mountains, ocean basins, and some of the world's largest, deepest, and oldest lake basins.

Fault block Fault block lake basins form where uplift and subsidence create vertical offset in adjacent blocks of fractured land. In cases where a single fault or fault complex is active, the process leads to a halfgraben. This type of basin has characteristic steep-walled bathymetry on the fault side and an angled floor that slopes gradually to the opposite shore where vertical offset is minimal or nonexistent. Where multiple fault lines occur with wide parallel spacing, both sides of a land block can experience vertical offset and create a trough-shaped basin called a graben. Grabens generally contain precipitous bathymetric contours along both main shorelines (Figure 7). They are characteristically flanked by massive, steep escarpments that crest hundreds to

Water level rises and original lake floods outwards to form a wide shallow lake; the deeper area within the lake is termed a 'kettle hole'

Figure 4 A schematic of how kettle lake basins originate. (a) Glacial retreat and ice block burial; (b) Post-melt; (c) General relationship between the size and shape of an ice block and a lake basin's bathymetry. Adapted from Hutchinson GE (1957) A Treatise on Limnology. Volume 1: Geography, Physics, and Chemistry. New York: Wiley. Exhaustive effort was made to secure permission.

Water level rises and original lake floods outwards to form a wide shallow lake; the deeper area within the lake is termed a 'kettle hole'

Figure 4 A schematic of how kettle lake basins originate. (a) Glacial retreat and ice block burial; (b) Post-melt; (c) General relationship between the size and shape of an ice block and a lake basin's bathymetry. Adapted from Hutchinson GE (1957) A Treatise on Limnology. Volume 1: Geography, Physics, and Chemistry. New York: Wiley. Exhaustive effort was made to secure permission.

thousands of meters above lake level (Figure 8). Well-known examples of fault block lakes include Lake Baikal (Russia), Lake Ohrid and Lake Prespa (Europe), Lake Issyk-Kul (Kyrgyzstan), Lake Tahoe (USA), and several lakes in the Central African Rift Valley District (Figure 9), including Lake Tanganyika, Lake Malawi, Lake Edward, Lake Albert, and Lake Rudolf. Some grabens that have been filled with water continuously for millions of years now house remarkably thick sediment layers such as those in Lake Baikal (—8 km thick) and Lake Tanganyika (—4.5 km thick). Such extraordinary sediment accumulations can only be explained if basin subsidence is ongoing. Evidence shows this to be the case which means that the longevity of these lakes depends in part on continual processes of origination.

Reverse drainage Reverse drainage lakes result from uplift and tilting that redirect drainage. Two well-known examples include Lake Kyoga and Lake Victoria in Africa (Figure 9). These lakes were created when uplift around the plateau's western margin reversed flow in the Kafu, Katonga, and Kagera Rivers. All three major rivers historically flowed east to west across the plateau but now flow west to east over much of their course, flooding what were once old river channels and riparian plains in the formation of these two lakes. The dendritic shoreline of Lake Kyoga and the angles of its bays with respect to the main arm of the lake remain vestiges to this day of an ancestral fluvial state and a history of drainage that once flowed east to west (Figure 9).

Newland Newland lake basins originate when a submarine basin on the sea floor is uplifted and becomes exposed. The Caspian Sea, Aral Sea, and Lake Okeechobee (Florida, USA) are examples. Despite their marine ontogeny, the Caspian Sea and Aral Sea currently house salts derived overwhelmingly from terrestrial sources.

Volcanic

Volcanism is responsible for a variety of lake basin types that can be divided relatively naturally into two groups. One group includes those forming directly in the volcanic chamber where magma exited. The other group includes basins that result from obstruction imposed by the volcanic mountain itself or the expelled magma. Volcanic lakes are

Figure 5 The historical border of proglacial Lake Agassiz (stippled) and the current borders of five remnant extant basins (blackened) in North America. Adapted from Timms BV (1992) Lake Geomorphology. Adelaide: Gleneagles. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

Figure 5 The historical border of proglacial Lake Agassiz (stippled) and the current borders of five remnant extant basins (blackened) in North America. Adapted from Timms BV (1992) Lake Geomorphology. Adelaide: Gleneagles. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

Figure 6 Examples of thaw lakes in Alaska (USA). Joel Sartore/ National Geographic Image Collection.

generally small but often deep and they comprise some of the world's most aesthetically pleasing and noteworthy ecosystems.

Volcanic crater Volcanic crater lake basins originate in the cavities from which magma was ejected. Small volcanic crater lakes (maars) and large ones (claderas) have representatives throughout the world, including many in the Eifel region (Germany), the Auvergne region (France), Indonesia, and central Africa. Because of their origin, these lakes generally have a small aspect ratio (maximum width:maximum depth), which can inhibit complete mixing (turnover) of the lake's water mass on an annual basis. Lake Nyos (Cameroon) is a maar with an aspect ratio of 9:1. In its recent history, Lake Nyos remained partially unmixed long enough to become supersaturated with carbon dioxide gas. A catastrophic episode of mass release of the gas in 1986 killed about 1700 humans and 3000 cattle. Crater Lake (USA) is a magnificent example of a caldera. At about 600 m depth, it is one of the top 10 deepest lakes in the world. Lake Tazawa and Lake Okama (Japan), and Lake Taupo (New Zealand) are other examples.

Volcanic dam Volcanic dam lakes originate as a result of drainage that is blocked by either a volcanic mountain or its expelled lava. One example is Lake Kivu, which lies on the western side of the Central African Rift Valley (Figure 9). In the origination of this lake, seven major volcanoes dammed a drainage pattern that historically flowed north into Lake Edward. Drainage in the watershed now accumulates in Lake Kivu, with excess water in the lake flowing

North America

North America

Figure 7 The bathymetry of Lake Tahoe (USA), a graben. The lake's maximum depth is slightly over 500 m. Adapted from Hutchinson GE (1957) A Treatise on Limnology. Volume 1: Geography, Physics, and Chemistry. New York: Wiley. Exhaustive effort was made to secure permission. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

Figure 8 The Livingstone Mountains of Tanzania define the eastern fault in the north basin of Lake Malawi (Africa), a half-graben. By kind permission of Tom Johnson, University of Minnesota Duluth.

south to Lake Tanganyika. Lake Lanao (Philippines) is another example of a volcanic dam lake.

Plunge pool As the name implies, a plunge pool lake basin originates at the base of a waterfall where the destructive energy of falling water excavates a hollow large enough to hold water long after the river has perished. A number of lakes in eastern Washington (USA) provide examples including Dry Falls Lake.

Oxbow An oxbow (billabong) lake basin originates through the coupled influence of erosion and deposition in what are often wide, gently sloping flood-plains. The general process, illustrated in Figure 10, is one whereby a meandering loop in a river is eventually abandoned as the river cuts a newer, more direct path through the bank. The old river course is sealed at both ends with sediment deposits. Oxbows are commonly serpentine or crescent shaped, which reflects their position in the old river channel. Innumerable examples of oxbows exist worldwide that can best be appreciated from aerial views (Figure 11).

Fluvial

Running water plays a profound role in sculpting the Earth's surface. Its dual ability to erode and construct, akin to glacial, tectonic, and volcanic forces, engender fluvial force with a wide range of originating processes.

Fluvial dam Fluvial dam lakes originate when deposited silt creates a barrier that impounds drainage. Most common among this spectrum of lakes is a lateral lake that originates when a tributary is obstructed from entering a main river by a levee at the confluence. Lateral lakes are frequent on the Danube River (Europe) and the Yangtze River

Eastern rift

CthiAnia

Eastern rift

CthiAnia

Figure 9 Lakes in the Central African Rift Valley District (blackened). Adapted from Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

0

Volcano

HB!

Lake

Wetland

Figure 9 Lakes in the Central African Rift Valley District (blackened). Adapted from Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc. Continental map courtesy of Graphic Maps, Woolwine-Moen Group. Reprinted by permission.

Oxbow Lakes Diagram

Figure 10 Diagram of an oxbow lake during the (a) precursor phase and (b) late phase of origination. Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc.

Figure 10 Diagram of an oxbow lake during the (a) precursor phase and (b) late phase of origination. Kalff J (2002) Limnology: Inland Water Ecosystems. Upper Saddle River: Prentice Hall. Reprinted by permission of Pearson Education, Inc.

(China). A second type of fluvial dam lake is called a floodplain lake. This type originates when a levee develops along the edge of a main river and obstructs seasonal floodwater of the main river from reentering.

The volume of a floodplain lake can shift by an order of magnitude on a seasonal basis in relation to rainfall. Floodplain lakes are common throughout low-latitude, riparian regions of South America.

Oxbow Lake Figure
Figure 11 Aerial photograph of four oxbow lakes flanking the Red River at the border of Minnesota and North Dakota (USA). Reprinted by permission of U.S. Department of Agriculture, Farm Service Agency, Aerial Photography Field Office.

Organism Behavior

Beaver pond Beavers are industrious ecosystem engineers that transform land surfaces from terrestrial to aquatic. Their dams are built of wood and mud for purposes of habitat expansion and predator protection. Beaver dams may reach 4 m in height and extend for up to 0.5 km in length, giving their aquatic impoundments the dimensions of small lakes. The European beaver (Castor fiber) was extirpated by trappers over most of its native range by 1900, and is now being reintroduced. A dire fate of similar proportions reduced the abundance of the American beaver (Castor canadensis) from an estimated 60-400 million individuals only two centuries ago to 6-12 million today. The remarkable numbers of beaver at one time suggest that their ponds may have once contributed significantly to lake numbers on a global scale.

Reservoir Reservoirs are human-made impoundments that block the natural flow of rivers and submerge formerly terrestrial surfaces. They are generally built for purposes of flood control, water supply, power generation, navigation, fish production, or recreation. Modern, highly engineered reservoirs are capable of retaining enormous volumes of water and controlling its passage at the outlet with great precision. The numbers and sizes of reservoirs have been growing worldwide at rapid rates since World War II. One of the largest is Bratsk Reservoir (Russia) with a volume that exceeds Lake Tahoe (USA).

Farm pond, Mine pit Humans have long been excavating basins to retain water for agricultural purposes. These basins, called farm ponds, are widespread globally and may be more important in their contribution to the total surface area of freshwater than once thought. Humans also excavate basins during mining operations for rocks, metals, and gems. These depressions are called mine pits and once abandoned they fill naturally with groundwater. Some mine pit lakes are remarkably deep. The Portsmouth Mine Pit Lake in Minnesota (USA) has a maximum depth of 150 m and a surface area of 0.5 km2, making it the state's deepest inland lake.

Chemical

Solution Solution (karst, doline) lake basins form through a process of chemical dissolution of bedrock. The breakdown of limestone (CaCO3) by natural levels of acidity in the groundwater is the most common chemical reaction involved. A solution lake basin generally originates as a subsurface cavern which progressively collapses under the strain of overlying soils. Solution basins have been known to appear suddenly, and disastrously, where large underground cavities collapse all at once. Subsurface outlets and cracks in solution basins may be sealed by residual rock, soil, or the hydrostatic pressure of the water table, including the ocean in coastal locations. They are common in the Balkan Peninsula, the European Alps, and Florida (USA).

Wind

Deflation Deflation (playa, pan) lake basins originate through the erosive force of wind that removes loose terrain. The process is facilitated by an arid climate and a lack of vegetative cover, and may be aided further in some instances by intermittent fluvial erosion and animal occupation (ungulates) which can help loosen sediment and reduce its grain diameter. Deflation lakes may dry up on a seasonal basis if precipitation and runoff are unable to maintain their evaporative losses. They are common throughout arid regions in Australia, Africa, and North America. One notable example is Lake Alablab (Kenya).

Landslide

Landslide dam A landslide is a gravitationally pushed, mass movement of debris. When one obstructs the passage of a river it originates a landslide dam lake. Because landslide debris is typically unconsolidated it erodes rapidly. These lakes are generally short-lived compared to other lake types. Two examples include Janet Lake in Glacier National Park (USA) and Lake Waikaremoana (New Zealand).

Figure 12 Aerial photograph of Stoney Lake (USA), a coastal lake of Lake Michigan (background). Reprinted by permission of Aerial Graphics, L.L.C., Grand Rapids, Michigan (USA).

Shoreline

Coastal Coastal lakes originate when a bay or indentation in the shoreline of a lake or ocean becomes closed to the main body of water by a bar (spit) of sediment deposited through longshore currents. It is a process similar to that which creates fluvial dam lakes. Maritime examples of coastal lakes are common in France, Australia, and New Zealand. Lake Nabugabo (Uganda) is an example of a freshwater coastal lake which was cut off from Lake Victoria. The western edge of the state of Michigan (USA) is rich with coastal lake basins sealed off from Lake Michigan (Figure 12).

Meteorite

Meteorite crater The most bizarre of all originating events, and the rarest at this moment in the Earth's history, is that related to the impact of a meteorite. In this process, the catastrophic destruction and dispersal of terrain leaves a hollow called a meteorite crater lake basin. Examples include Pingualuit Crater Lake in Quebec (Canada) and Laguna Negra (Argentina).

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Responses

  • Livia
    What is destructive, constractive and obstructive process of lake formation?
    1 year ago

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