Oak Ridges Moraine
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The Oak Ridges Moraine is an ecologically sensitive geological landform in south central Ontario, Canada. The moraine covers a geographic area of 190,000 hectares between Milton and Rice Lake, near Peterborough. One of the most significant landforms in southern Ontario, the moraine gets its name from the rolling hills and river valleys extending 160 km from the Niagara Escarpment to Rice Lake. It was formed 12,000 years ago by advancing and retreating glaciers (see geological origins, below). The moraine is currently a contested site in Ontario, since it stands in the path of major urban development (see political action).
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Ecology
Main article: Ecology of the Oak Ridges Moraine
The ecologically diverse moraine is the source for many headwaters streams flowing south into rivers that drain into Lake Ontario and north into rivers that drain into Lake Scugog and Lake Simcoe. Varied landforms on the moraine, such as woodlands, wetlands, watercourses, and kettle lakes and bogs, have provided an environment suitable for significant flora and fauna communities to develop and thrive. The moraine contains one of the last contiguous forested spans in southern Ontario.
Some of the wide variety of plant and animal species found in the moraine are threatened or endangered in Canada, including the West Virginia White Butterfly, Jefferson Salamander, Red-shouldered Hawk, and American Ginseng. Unique ecosystems in the moraine include wetlands similar to those of boreal forests in Northern Ontario, and remnants of tallgrass prairie and oak-pine savanna that are globally threatened ecosystems. A typical portion of the moraine may be found in the Happy Valley Forests, in York Region, north of Toronto.
Development pressures
The greatest threat to the function of the moraine is land development on and below its surface, particularly in the headwaters. Five million people live on or near the moraine. Use of the moraine is currently under dispute; environmental groups such as the Sierra Club maintain the area's delicate ecosystem is threatened by development pressures. Attractive forests and hilly relief typical of the moraine are a magnet for developers looking for building opportunities in the densely populated Greater Toronto Area. However, many planners and residents see a need to preserve the moraine from the negative aspects of urban sprawl.
Moreover, because it is a rich resource of sand and gravel, it has become a significant source of materials for the aggregate industry of the Greater Toronto Area.Template:Ref
Geological origins
Main article: Origin of the Oak Ridges Moraine
The Oak Ridges Moraine probably formed in the Late Wisconsonian glacial period. Ice melt from the Niagara Escarpment flowed into the western boundaries of the moraine, wherein conduits beneath the ice expanded to form a west-to-east passage between the main Laurentide ice sheet and a mass of ice in the Lake Ontario basin.
Stratified sediment was deposited rapidly on the erosional surface, up to 150 m in some areas. Sedimentation from glacial rivers forms the core of the Oak Ridges Moraine; overlaying this core is a glacial lake sedimentary layer that is younger and topographically lower. In the late stages of its development, random unstratified accumulation occurred along the ice margins. Known as diamicton, the deposits represent a major portion of the moraine's exposed surface.
Hydrology
Preliminary research on the hydrology of the moraine began in the 1970s, but a broader research effort including the impact of urban development on the aquifer system and Great Lakes water quality was established in 1993.Template:Ref The research locus is the Geological Survey of Canada and the University of Toronto Groundwater Research Group, though other groups have made substantial contributions to this project.
The moraine serves to recharge streams and rivers in the surrounding region, acting like a giant rain barrel. Rain and snow melt slowly soak into the moraine, being filtered and purified in its many sand and gravel aquifers. The cool, fresh water is discharged into the headwaters of streams and rivers which eventually flow into Lake Simcoe, Lake Scugog and Lake Ontario. The aquifers are also the water supply for some communities on the Moraine.
The moraine's hydrological system is inter-twined with a regional flow system not bound by the morphological limits of the moraine.Template:Ref For this reason, environmentalists and researchers promote an aggressive protection strategy extending beyond the moraine, thus ensuring a contiguously protected hydrological system.
A number of features comprise the hydrological system of the Oak Ridges MoraineTemplate:Ref:
- permanent and ephemeral streams,
- wetlands,
- kettle lakes and ponds, and their catchment areas,
- seepage areas and springs, and
- aquifers and other recharge areas.
The Oak Ridges Moraine Conservation Act stipulates that any development which targets the moraine or nearby areas must satisfy several conditions, most prominently that each development leave a buffer zone of 30 m between it and any hydrological feature; for a kettle lake, this measure is from the edge of the lake's catchment area.
The Oak Ridges Moraine's hydrological system is a major constituent of the Humber Watershed, so that any impact on this sytem will be of concern. A specific concern is urbanization, which affects water quality by increasing its load of metals and organic contaminants.Template:Ref A study by Cook et al (1985) found an increase in mean annual runoff, instantaneous discharge, and hydrograph peak flow as a result of urbanization: "...changes in land use coincided with changes in volumetric and time distribution aspects of hydrologic response."
At least thirteen watersheds are linked to the Oak Ridges Moraine, and are managed by various organizations.
| Watershed | Conservation Authority |
|---|---|
| Innisfil Creek Sub-watershed | Nottawasaga Valley Conservation Authority |
| Credit River Watershed | Credit Valley Conservation |
| Black River Watershed | Lake Simcoe Region Conservation Authority |
| Humber River Watershed | Toronto and Region Conservation Authority |
| Don River Watershed | Toronto and Region Conservation Authority |
| Rouge River Watershed | Toronto and Region Conservation Authority |
| Duffins Creek Watershed | Toronto and Region Conservation Authority |
| Kawartha Conservation Watershed | Kawartha Conservation |
| Trout Creek Watershed | Otonabee Region Conservation Authority |
| Wilmot Creek Watershed | Ganaraska Region conservation Authority |
| Ganaraska River Watershed | Ganaraska Region conservation Authority |
| Gage Creek Watershed | Ganaraska Region conservation Authority |
| Cobourg and Baltimore Creeks Watershed | Ganaraska Region conservation Authority |
(Note: the above table excludes watersheds managed by the Central Lake Ontario Conservation Authority and Lower Trent Conservation Authority.)
Research on the moraine
In 1829, Bigsby conducted the first investigation of the moraine.Template:Ref He noted the elevation, and styled the area Oak Ridge, identifying the portion of moraine north of Toronto. It wasn't until Logan, in 1863, that the moraine's extent was established to be between the Niagara Escarpment in the west, and the Trent River in the east.
Taylor formally defined the landform as the Oak Ridges Moraine in 1913. He described its extent to be from King and Maple in the west to the Trent River in the east. He also theorized that its origin was overlapping, interlobate glaciation retreat, between the Lake Ontario Lobe and the older Lake Simcoe Lobe. This has become the accepted explanation for the moraine's development, though research in the 1970s suggested the moraine may not be interlobate.
Research conducted in the 1990s reveals that the moraine has multiple origins: its eastern area has subglacial depositions (Gorrell and McCrae, 1993); early parts of the moraine were deposited in an esker (Brennand and Shaw, 1994); and that the moraine is not continuous, but is composed of multiple depositional environments: subglacial, ice-marginal and proglacial lacustrine (Barnett et al, 1998).
Political action
Main article: Politics of the Oak Ridges Moraine
Although preservation of the moraine was first suggested in the 1940s, it was not until 1991 that the issue achieved prominence in political discourse.Template:Ref
The Government of Ontario created the Oak Ridges Moraine Technical Working Committee in June 1991, with the aim to create a regional planning strategy for the moraine. The plan was completed in 1994, but was subsequently dismissed in favour of local government administration of the affected lands. This led to intense development on some portions of the moraine.
In early 1999, developers targeted Richmond Hill for large subdivisions on the moraine which would house over 100,000 people. A media campaign by environmental groups led to public opposition of the developments, and the issue was transferred to the Ontario Municipal Board (OMB) in 2000.
By May 2001, with the issue still unresolved, the provincial Conservative government announced a six-month moratorium on moraine development. A panel was formed to create a land-use plan consistent with the current "smart growth" policy. The plan was released in October 2001, and became the basis for the Oak Ridges Moraine Conservation Act, dividing the area into four zones with increasingly stringent controls on development in each.
During the provincial election of 2003, the Liberal Party of Ontario promised to terminate development on the moraine as part of their election campaign. The government, in its attempt to halt developments, proposed the North Pickering Land Exchange.Template:Ref This involved exchanging government-owned public lands in North Pickering (the Seaton lands) for privately-owned lands on the Oak Ridges Moraine in Richmond Hill and Uxbridge. The exchange settled outstanding disputes being considered by the OMB involving moraine lands in Richmond Hill and Uxbridge.
Despite all these efforts, the political struggle regarding the moraine continues.
See also
References
- Template:Note Government of Ontario - Ministry of Municipal Affairs and Housing: More facts about the Oak Ridges Moraine (http://www.mah.gov.on.ca/userfiles/HTML/nts_1_3631_1.html)
- Template:Note STORM Coalition: The Moraine (http://www.stormco.org/aspx/themoraine.aspx)
- Template:Note National Research Council of Canada - Hydrogeology of the Oak Ridges Moraine aquifer system: implications for protection and management from the Duffins Creek watershed (http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_abst_e?cjes_e02-058_39_ns_nf_cjes)
- Template:Note Achieving Ecological Integrity on the Oak Ridges Moraine: Towards Ecologically Relevant Water Management (http://www.soe.uoguelph.ca/webfiles/abradfor/Assets/Text/ORM%20Paper.pdf)
- Template:Note Watershed: Issues in Stormwater Quality and Quantity in the Humber (University of Toronto, Department of Geography) (http://www.unc.edu/~davidten/wisqqih/context/)
- Template:Note On the Origin of the Oak Ridges Moraine (Barnett et al, 1998, PDF) (http://www.sfu.ca/~tabrenna/pubs_files/Barnettetal98_ORM_CJES.pdf)
- Template:Note International Association for Great Lakes Research - Case Study: The Oak Ridges Moraine (2002) (http://www.iaglr.org/scipolicy/nps/oakridges.php)
- Template:Note Government of Ontario - Ministry of Municipal Affairs and Housing: North Pickering Land Exchange (http://www.mah.gov.on.ca/userfiles/HTML/nts_1_6592_1.html)
External links
- Government of Ontario - Ministry of Municipal Affairs and Housing: The Oak Ridges Moraine (http://www.mah.gov.on.ca/userfiles/HTML/nts_1_31_1.html)
- Natural Resources Canada - Earth Sciences Sector: Oak Ridges Moraine Groundwater Research (http://sts.gsc.nrcan.gc.ca/orm_dcp/index_e.asp)
- Natural Resources Canada: Oak Ridges Moraine - A Ridge of Resources (http://sts.gsc.nrcan.gc.ca/geoscape/toronto_dcp/index_e.asp?CaId=5&PgId=13)
- Nature Conservancy Canada: The Oak Ridges Moraine (http://www.natureconservancy.ca/templates/template013.asp?lang=e_®ion=1&sec=projects&screen=135&id=398&order=4&action=region)