Surficial geology of the Greater Toronto and Oak Ridges Moraine area, southern Ontario

Sharpe, D R; Barnett, PJ; Brennand, T A; Finley, D; Gorrell, G; Russell, H A J; Stacey, P

doi:10.4095/209298

Cited by 22 publications

(20 citation statements)

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“…The upper reaches of the channel flow through a glaciolacustrine landform complex that was formed at the time of the glacial Lake Iroquois. The valley complex is cut into the glaciolacustrine deposits and underlying till, where sandy and silty interbeds along with stone lines result in a wide range of particle sizes supplied to the creek, with significant local variation (Sharpe et al, 1997). In contrast, the lower reaches flow through a valley landform complex that was formed when Lake Iroquois drained and the water level dropped closer to the current level of Lake Ontario.…”

Section: Site Descriptionmentioning

confidence: 99%

“…Wilket Creek drains a small watershed (A d = 14.8 km 2 ) located entirely within the City of Toronto (Figure 1). A tributary of the Don River, the watershed is located on the Halton Till Plain and underlain by Newmarket Till, a dense, stony (>5% gravel or larger), silty sand diamicton (Sharpe et al, 1997). The upper reaches of the channel flow through a glaciolacustrine landform complex that was formed at the time of the glacial Lake Iroquois.…”

Section: Site Descriptionmentioning

confidence: 99%

“…In contrast, the lower reaches flow through a valley landform complex that was formed when Lake Iroquois drained and the water level dropped closer to the current level of Lake Ontario. The valley complex is cut into the glaciolacustrine deposits and underlying till, where sandy and silty interbeds along with stone lines result in a wide range of particle sizes supplied to the creek, with significant local variation (Sharpe et al, 1997). Sediments in the valley complex are relatively coarse and valley walls can be up to 40 m in height (Thayer et al, 2016).…”

Section: Site Descriptionmentioning

confidence: 99%

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Enlargement and evolution of a semi‐alluvial creek in response to urbanization

Bevan

MacVicar

Chapuis

et al. 2018

Earth Surf Processes Landf

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The impact of urbanization on stream channels is of interest due to the growth of cities and the sensitivity of stream morphology and ecology to hydrologic change. Channel enlargement is a commonly observed effect and channel evolution models can help guide management efforts, but the models must be used in the proper geologic and climatic context. Semi‐alluvial channels characterized by a relatively thin alluvial layer over clay till and a convex channel profile in a temperate climate are not represented in currently available models. In this study we: (i) assess channel enlargement; and (ii) propose a channel evolution model for an urban semi‐alluvial creek in Toronto, Canada. The system is 90% developed with an imperviousness of approximately 47%. Channel enlargement is assessed by comparing 50 year old construction surveys, a recent survey of a relic channel, low‐precision surveys of channel change over a 15 year period, and high‐precision surveys over a three year period. The enlargement ratio of the channel since 1958 is 2.6, but could be as high 8.2 in comparison with the pre‐urban channel. When the increase in flow capacity is considered, the enlargement ratio is 1.9 since 1958 and up to 6.0 in comparison with the pre‐urban channel. Channel enlargement continues in the contemporary channel at an estimated rate of 0.23 m2/year. A five stage model is presented to describe channel evolution in the lower reaches. In this model the coarse lag material from glacial sources provides a natural resilience to the bed and incision occurs only after the increased flows from urbanization are combined with higher slopes as a result of channel straightening or avulsions. Further research should be done to assess stream behaviour close to an identified geologic control point. Copyright © 2018 John Wiley & Sons, Ltd.

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Section: Site Descriptionmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

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Enlargement and evolution of a semi‐alluvial creek in response to urbanization

Bevan

MacVicar

Chapuis

et al. 2018

Earth Surf Processes Landf

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“…Creek is a tributary of the Don River in the City of Toronto, Canada with a watershed area of 14.9 km 2 ( Figure 1). The surficial geology of the watershed is Newmarket Till, a dense silty sand diamicton with >5% gravel or larger particles that rests over the Halton Till plain (Sharpe et al, 1997). Upstream sections of the channel consist of sandy bed material and low valley incision, formed from glaciolacustrine deposits at the time of glacial Lake Iroquois.…”

Section: Introductionmentioning

confidence: 99%

Process‐based assessment of success and failure in a constructed riffle‐pool river restoration project

Papangelakis

MacVicar

2020

River Research & Apps

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Although there is increasing consensus that river restoration should focus on restoring processes rather than form, proven techniques to design and monitor projects for sediment transport processes are lacking. This study monitors bedload transport and channel morphology in a rural, an urban unrestored, and an urban restored reach. Objectives are to compare bedload transport regimes, assess the stability and self‐maintenance of constructed riffle‐pool sequences, and evaluate the impact of the project on coarse sediment continuity in the creek. Sediment tracking is done using radio frequency identification tracers and morphologic change is assessed from repeated cross‐section surveys. Mean annual velocity is used to quantify the average downstream velocity of tracers, defined as the mean overall tracer travel length divided by the total study duration. The channel reconstruction slows down the downstream velocity of particles in the D75 and D90 size classes, but does not significantly change the velocity of particles in the D50 size class or smaller. Surveys show that riffle features remain stable and that pool depths are maintained or deepened, while tracer paths match with what has been observed in natural riffle‐pools. However, the slowdown of coarse sediment and increase in channel slope may lead to future failures related to over‐steepening of the banks and a disruption in the continuity of sediment transport in the creek. This study demonstrates how bedload tracking and morphological surveys can be used to assess river restoration projects, and highlights the importance of incorporating coarse sediment connectivity into restoration design and monitoring.

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“…Primary training data consist of surface geological maps (Sharpe et al, 1997) and subsurface data with reliable geological integrity (Logan et al, 2006). The subsurface component included: i) continuous cored boreholes, ii) measured sections, iii) seismic reflection picks, and iv) ∼5000 geotechnical and hydrogeological boreholes.…”

Section: Datamentioning

confidence: 99%

A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada

Sharpe¹,

Russell²,

Logan³

2007

Journal of Maps

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The Oak Ridges Moraine area, southern Ontario, includes most of the Greater Toronto Area, which is the most populated region of Canada. The ∼11,000 km 2 region is bounded to the south by Lake Ontario and to the north where Paleozoic bedrock abuts Precambrian Canadian Shield. The area extends 160 km eastward from the Niagara Escarpment, a prominent 100 m high regional bedrock scarp. The surficial sediment is up to 200 m thick, and reveals exposures of the oldest Quaternary sediment in southern Canada. Population growth has caused land use conflicts and increased pressure on groundwater resources. Construction of a regional 3-D geological model of the glacial stratigraphy was needed to support a better understanding of aquifer distribution, scale, and resource potential and protection.Mapping of the regional glacial geomorphology and sediment succession identified a number of distinct landforms: tunnel channels, drumlins, eskers, moraines, and till and lacustrine plains. Using sequence stratigraphic concepts, strata have been grouped into four principal units that unconformably overlie Paleozoic bedrock: Lower sediment, Newmarket Till, Oak Ridges Moraine, and Halton Till.These four Quaternary units plus bedrock have been mapped in the subsurface as a succession of interpolated surfaces using an innovative stratigraphic database-GIS approach. The model-building process involved stratigraphically coding high-quality data, then integrating an extensive and diverse array of subsurface geological and archival datasets using an expert system (geological rules). Stratigraphic data subsets were then extracted and merged with DEM-controlled surface mapping and interpolated in a GIS.

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Surficial geology of the Greater Toronto and Oak Ridges Moraine area, southern Ontario

Cited by 22 publications

References 0 publications

Enlargement and evolution of a semi‐alluvial creek in response to urbanization

Enlargement and evolution of a semi‐alluvial creek in response to urbanization

Process‐based assessment of success and failure in a constructed riffle‐pool river restoration project

A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada

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