Wetland vegetation response to record-high Lake Ontario water levels

The Laurentian trough (LT), a depression >100 km long, >3000 km2 in area, and 100 m deep at the base of the Niagara Escarpment, extends from within Georgian Bay to Lake Ontario. It has a complex erosional history and is filled and buried by up to 200 m of interglacial and glacial sediment. The primary depression fronts a cuesta landscape and is attributed to differential erosion by fluvial, glacial, and glaciofluvial processes, exposing Ordovician rocks along the Canadian Shield margin. The fill succession includes sediments from the last two glacial periods (Illinoian, Wisconsinan) and the intervening interglacial time (Sangamonian), a poorly dated succession with at least three regional unconformities. A subaerial (interglacial, Don Formation) unconformity relates to low base level mainly preserved in lows of the LT, succeeded by a long period of rising water levels and glaciolacustrine conditions as ice advanced into the Lake Ontario basin. A second unconformity, within the Thorncliffe Formation, is the result of rapid channel erosion to bedrock, forming an ∼north–south network filled with coarse-grained glaciofluvial, transitional to fine-grained glaciolacustrine subaqueous fan sediment. The overlying drumlinized Newmarket Till, up to 50 m thick, is a distinct regional unit with a planar to undulating base. A third unconformity event eroded Newmarket Till, locally truncating it and underlying sediment to bedrock. Three younger sediment packages, Oak Ridges Moraine (channel and ridge sediment), Halton, and glaciolacustrine overlie this erosion surface. Significant regional aquifers are hosted within the LT. Upper Thorncliffe Formation sediments, north–south glaciofluvial channel–fan aquifers, are protected by overlying mud and Newmarket Till aquitards. Similarly, Oak Ridges Moraine sediments comprise a north–south array of glaciofluvial channel–fans and east–west fan aquifers, locally covered by silt–clay rhythmite and till aquitards.

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Some implications of crustal movement in engineering planning

Canadian Journal of Earth Sciences ◽

10.1139/e70-064 ◽

1970 ◽

Vol 7 (2) ◽

pp. 628-633 ◽

Cited By ~ 21

Author(s):

R. H. Clark ◽

N. P. Persoage

Keyword(s):

Great Lakes ◽

Lake Ontario ◽

Water Levels ◽

Crustal Movement ◽

Earth’S Crust ◽

Lake Huron ◽

Great Lakes Basin ◽

Lake Outlet ◽

Earth's Crust ◽

Bodies Of Water

Movements of the earth's crust causing progressive changes in the levels of large bodies of water relative to their shorelines may influence the formulation of water resource projects and/or their continuing effectiveness with time. In the Great Lakes basin there is evidence of an uplift of the earth's crust, of about 1 ft per 100 y, in the northeasterly part of the basin relative to that in the southwest. This results in a corresponding lowering of water levels along the northeasterly shorelines and a rise in water levels along the southwest shores. In at least two of the lakes, Lake Huron and Lake Ontario, the average depth of water will change with time. In Lake Huron, it will gradually decrease because the bed underlying the lake is rising with respect to the lake outlet. In Lake Ontario, the depth of water will increase since the lake outlet is rising with respect to the remainder of the lake. This paper reviews some of the engineering implications of the relative rates of crustal movement in the Great Lakes region on long-term management of the water levels of the Great Lakes.

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Submerged Macrophytes in Lake Ontario: Current Knowledge, Importance, Threats to Stability, and Needed Studies

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-182 ◽

1991 ◽

Vol 48 (8) ◽

pp. 1539-1545 ◽

Cited By ~ 35

Author(s):

A. Crowder ◽

D. S. Painter

Keyword(s):

Invasive Species ◽

Nutrient Cycling ◽

Cyprinus Carpio ◽

Submerged Macrophytes ◽

Current Knowledge ◽

Lake Ontario ◽

Water Levels ◽

Carp Cyprinus Carpio ◽

Nursery Habitats ◽

High Concentrations

The submerged limnetic community in Lake Ontario includes algae, bryophytes, and about 30 species of angiosperms. Their distribution is accurately known in some areas but not lake-wide, and a whole-lake survey is recommended. In nutrient cycling, submergents act as sinks during the summer; metals and metalloids occur in high concentrations in tissues from some areas. Known herbivores include invertebrates, fish, and waterfowl. Stands are necessary for many fish taxa as breeding or nursery habitats, and for waterfowl, but may be damaged by carp (Cyprinus carpio). Stability has been affected by water levels, sedimentation, wave and ice movement, invasive species, herbivory, eutrophication and turbidity, and contaminants. Recovery after control of P loading has occurred in Irondequoit Bay but is delayed by turbidity in the Bay of Quinte.

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Cyclic fluctuations of water levels in Lake Ontario

Computers & Geosciences ◽

10.1016/0098-3004(75)90010-2 ◽

1975 ◽

Vol 1 (1-2) ◽

pp. 105-108 ◽

Cited By ~ 7

Author(s):

Barry P. Cohn ◽

Joseph E. Robinson

Keyword(s):

Lake Ontario ◽

Water Levels

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Stratigraphy of the Sixteen Mile Creek lagoon, and its implications for Lake Ontario water levels

Canadian Journal of Earth Sciences ◽

10.1139/e88-115 ◽

1988 ◽

Vol 25 (8) ◽

pp. 1175-1183 ◽

Cited By ~ 11

Author(s):

J. E. Flint ◽

R. W. Dalrymple ◽

J. J. Flint

Keyword(s):

Water Level ◽

Lake Michigan ◽

Drainage Basin ◽

Average Rate ◽

Lake Ontario ◽

Open Water ◽

Water Levels ◽

Beach Sand ◽

Water Level Fluctuations ◽

Lake Outlet

The sequence of units (from the base up) in the Sixteen Mile Creek lagoon (Lake Ontario) mimics the longitudinal sequence of surficial environments: pink silt—overbank (flood plain – dry marsh); bottom sand—stream channel and beach; orange silt—marsh; gyttja—wet marsh and very shallow (deltaic) lagoon; and brown and grey clay—open-water lagoon. This entire sequence accumulated over the last 4200 years under slowly deepening, transgressive conditions caused by the isostatic rise of the lake outlet. Land clearing by European settlers dramatically increased the supply of clastic sediment and terminated the deposition of the organic-rich silty clays (gyttja) that make up most of the lagoon fill.Because the gyttja and beach sand are interpreted to have accumulated in water depths of less than 0.5 m, the elevation–time plot of 14C dates from these units can be used to reconstruct a very closely constrained lake-level curve. The data indicate that water levels have risen at an average rate of 0.25 cm/a over the last 3300 years as a result of differential, isostatic rebound. Superimposed on this trend are water-level oscillations with amplitudes on the order of 1 m and periods of several hundred years. These oscillations are synchronous and in phase with water-level fluctuations in Lake Michigan, and with a variety of other climatic variations in North America and Europe. We propose, therefore, that the water-level oscillations are a result of long-term, climatically produced variations in precipitation in the Great Lakes drainage basin.

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