Glacial Lake Bassano
Encyclopedia
Glacial Lake Bassano was formed in the Late Pleistocene
during the deglaciation of south-central Alberta
by the impoundment of the re-established proglacial drainage system
and addition of glacial meltwater
. It is associated with the development of through-flowing drainage within the Red Deer River
basin in particular, and the South Saskatchewan
drainage network in general. Approximately 7,500 square kilometers of the Bassano basin is covered with lacustrine
sediments. These sediment
s are bordered by the topographically higher Buffalo Lake Moraine to the west, the Suffield Moraine to the east and the Lethbridge Moraine to the south.
The transmission of water through the basin was ultimately controlled by the regional topography and the position of the ice front. As the Laurentide Ice Sheet
retreated, lower outlet channels were exposed. The lake levels at any given time were constrained by the elevation of the lowest drainage channel. As Glacial Lake Bassano, and the proglacial lake
system as a whole developed, throughflow in individual channels waxed, waned and reversed, depending on the systemic controls.
an Laurentide Ice Sheet in Alberta was accompanied by the deposition of extensive areas of proglacial lake sediments associated with ice frontal positions. These lakes formed as a result of impoundment of the re-established proglacial drainage system and glacial
meltwater. Quigley (1980) estimates that roughly 50% of Alberta was occupied by these short-lived lakes. The mapping of sediments deposited by lacustrine and related glacial processes allows the determination of ice-frontal positions at sequential recessional phases. St. Onge (1972), for example, constructed a detailed and comprehensive series of glacial-marginal positions for north-central Alberta. There are, however, a wide variety of chronological interpretations and problems related to the proposed ice-marginal positions in Southern Alberta
. Work on individual glacial lakes in Southern Alberta has not produced a definitive synthesis of the deglacial landscape. Early work was hampered by a lack of precise elevational control; later work has suffered from a paucity of chronological control and the lack of any detailed study of the integrated relationships between the proglacial lakes in southern Alberta. By topograhic analysis, it is possible to accurately determine the sequence of formation and drainage, as well as the maximum and minimum elevations of the proglacial lakes
In southern Alberta, the network of proglacial lakes lowered, with recession of the Laurentide Ice Sheet, from the 1100m maximum elevation of Glacial Lake McLeod to the final 680m elevation of Glacial Lake Empress. The confluence of flow through Glacial Lakes Drumheller, Gleichen and Lethbridge utilized Etzikom Coulee to enter the Missouri Drainage System. When Etzikom Coulee
was abandoned at 915m (the height of the Lethbridge Moraine Divide) discharge from the lakes was entirely within Alberta.
Glacial Lake Drumheller abandoned the Strathmore Channel at 945m, whereupon discharge was directed through the smaller Crowfoot channel until 915m. At this elevation, flow must have been diverted further to the east, over the Bassano basin. Glacial Lake Gleichen abandoned the southward-flowing McGregor Lake Channel at 860m and discharged eastward into Glacial Lake Bassano until channelization occurred at 850m.
With recession of the ice, Glacial Lake Lethbridge lowered and extended eastward, forming Glacial Lake Taber, whose upper level was controlled by Chin Coulee (915m). Subsequent drainage flowed through Forty Mile Coulee until 792m and along the valley of the South Saskatchewan, which became channelized at 760m. Glacial Lake Medicine Hat formed at roughly 760m and ponding at that location was associated with the formation of Glacial Lake Empress to the north at roughly the same elevation.
Glacial Lake Bassano existed from a maximum elevation of 915m until final drainage at690-700m. Its initiation coincides with the abandonment of southward-flowing drainage into the Missouri System and the beginning of drainage within Alberta. Together with Glacial Lake Tilley to the south, Glacial Lake Bassano received the discharge from over 1000 km of the Laurentide Ice Sheet and associated proglacial lakes.
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
during the deglaciation of south-central Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
by the impoundment of the re-established proglacial drainage system
Drainage system (Geomorphology)
In geomorphology, a drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. Geomorphologists and...
and addition of glacial meltwater
Meltwater
Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...
. It is associated with the development of through-flowing drainage within the Red Deer River
Red Deer River
The Red Deer River is a river in Alberta, Canada. It is a major tributary of the South Saskatchewan River.Red Deer River has a total length of and a drainage area of...
basin in particular, and the South Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
drainage network in general. Approximately 7,500 square kilometers of the Bassano basin is covered with lacustrine
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
sediments. These sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s are bordered by the topographically higher Buffalo Lake Moraine to the west, the Suffield Moraine to the east and the Lethbridge Moraine to the south.
The transmission of water through the basin was ultimately controlled by the regional topography and the position of the ice front. As the Laurentide Ice Sheet
Laurentide ice sheet
The Laurentide Ice Sheet was a massive sheet of ice that covered hundreds of thousands of square miles, including most of Canada and a large portion of the northern United States, multiple times during Quaternary glacial epochs. It last covered most of northern North America between c. 95,000 and...
retreated, lower outlet channels were exposed. The lake levels at any given time were constrained by the elevation of the lowest drainage channel. As Glacial Lake Bassano, and the proglacial lake
Proglacial lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice...
system as a whole developed, throughflow in individual channels waxed, waned and reversed, depending on the systemic controls.
Proglacial Lake System
The retreat of the late WisconsinWisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
an Laurentide Ice Sheet in Alberta was accompanied by the deposition of extensive areas of proglacial lake sediments associated with ice frontal positions. These lakes formed as a result of impoundment of the re-established proglacial drainage system and glacial
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
meltwater. Quigley (1980) estimates that roughly 50% of Alberta was occupied by these short-lived lakes. The mapping of sediments deposited by lacustrine and related glacial processes allows the determination of ice-frontal positions at sequential recessional phases. St. Onge (1972), for example, constructed a detailed and comprehensive series of glacial-marginal positions for north-central Alberta. There are, however, a wide variety of chronological interpretations and problems related to the proposed ice-marginal positions in Southern Alberta
Southern Alberta
Southern Alberta is a region located in the Canadian province of Alberta. As of the year 2004, the region's population was approximately 272,017. The primary cities are Lethbridge and Medicine Hat...
. Work on individual glacial lakes in Southern Alberta has not produced a definitive synthesis of the deglacial landscape. Early work was hampered by a lack of precise elevational control; later work has suffered from a paucity of chronological control and the lack of any detailed study of the integrated relationships between the proglacial lakes in southern Alberta. By topograhic analysis, it is possible to accurately determine the sequence of formation and drainage, as well as the maximum and minimum elevations of the proglacial lakes
In southern Alberta, the network of proglacial lakes lowered, with recession of the Laurentide Ice Sheet, from the 1100m maximum elevation of Glacial Lake McLeod to the final 680m elevation of Glacial Lake Empress. The confluence of flow through Glacial Lakes Drumheller, Gleichen and Lethbridge utilized Etzikom Coulee to enter the Missouri Drainage System. When Etzikom Coulee
Etzikom Coulee
Etzikom Coulee is a coulee located in Southern Alberta, Canada.The waterway was formed as a glacial spillway channel at the end of the last ice age.-Course:...
was abandoned at 915m (the height of the Lethbridge Moraine Divide) discharge from the lakes was entirely within Alberta.
Glacial Lake Drumheller abandoned the Strathmore Channel at 945m, whereupon discharge was directed through the smaller Crowfoot channel until 915m. At this elevation, flow must have been diverted further to the east, over the Bassano basin. Glacial Lake Gleichen abandoned the southward-flowing McGregor Lake Channel at 860m and discharged eastward into Glacial Lake Bassano until channelization occurred at 850m.
With recession of the ice, Glacial Lake Lethbridge lowered and extended eastward, forming Glacial Lake Taber, whose upper level was controlled by Chin Coulee (915m). Subsequent drainage flowed through Forty Mile Coulee until 792m and along the valley of the South Saskatchewan, which became channelized at 760m. Glacial Lake Medicine Hat formed at roughly 760m and ponding at that location was associated with the formation of Glacial Lake Empress to the north at roughly the same elevation.
Glacial Lake Bassano existed from a maximum elevation of 915m until final drainage at690-700m. Its initiation coincides with the abandonment of southward-flowing drainage into the Missouri System and the beginning of drainage within Alberta. Together with Glacial Lake Tilley to the south, Glacial Lake Bassano received the discharge from over 1000 km of the Laurentide Ice Sheet and associated proglacial lakes.