| Revision as of 01:36, 23 April 2006 editJohn Reed Riley (talk | contribs)186 editsm →Notes: Reordered notes so that the labels correspond to the numbers in text.← Previous edit | Revision as of 14:20, 3 May 2006 edit undo69.223.62.253 (talk)No edit summaryNext edit → | ||
| Line 1: | Line 1: | ||
| The '''Oak Ridges Moraine''' is an ] sensitive ] landform in south central ], ]. The ] covers a geographic area of 1,900 square kilometres between ] and ], near ]. 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 ] to Rice Lake. It was formed 12,000 years ago by advancing and retreating glaciers (''see'' ], below). The moraine is currently a contested site in Ontario, since it stands in the path of major urban development (''see'' ]). | |||
| ] | |||
| ==Ecology== | |||
| {{main|Ecology of the Oak Ridges Moraine}} | |||
| The ] moraine is the source for many ] flowing south into rivers that drain into ] and north into rivers that drain into ] and ]. Varied landforms on the moraine, such as ]s, ]s, ], and ] and bogs, have provided an environment suitable for significant ] and ] communities to develop and thrive. The moraine contains one of the last contiguous forested spans in southern Ontario. | |||
| ] is a threatened species in Canada. Happy Valley Forests is one of the few remaining Canadian habitats for this species.]] | |||
| Some of the wide variety of plant and animal species found in the moraine are threatened or endangered in Canada, including the ], ], ], and ]. Unique ecosystems in the moraine include wetlands similar to those of boreal forests in Northern Ontario, and remnants of ] and oak-pine ] that are globally threatened ecosystems. A typical portion of the moraine may be found in the ], in York Region, north of Toronto. | |||
| ==Physiography== | |||
| The Oak Ridges Moraine is a large ridge composed of four elevated wedges. It is bounded to the west by the Niagara escarpment, a ] which was critical to the formation of the moraine, and to the east by the ] and Rice Lake. The four wedges (''Albion'', ''Uxbridge'', ''Pontypool'' and ''Rice Lake'' from west to east) formed in stages, though some synchronous formation also occurred at an early period of formation. The moraine peaks at the Uxbridge wedge, generally rising from east to west, a result of the moraine's west-to-east formation. That is, the western portion of the moraine received earlier and more frequent sedimentary deposition than the eastern portion, as the ice lobes which controlled the moraine's eastern formation slowly retreated. The Rice Lake wedge is separated from the other wedges where the Oak Ridges Moraine intersects Rice Lake. | |||
| To the north are ] uplands, referred to as the ''Peterborough drumlin field''. | |||
| ==Geological origins== | |||
| {{main|Origin of the Oak Ridges Moraine}} | |||
| The Oak Ridges Moraine probably formed in the ] 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 ] and a mass of ice in the Lake Ontario basin. | |||
| Stratified sediment was deposited rapidly on the high-relief ] surface. Up to 150 m in some areas, the deposits occurred on surfaces defined by highly eroded channels and ] uplands. The channel tunnels were primarily created by the erosion from glacial rivers, a typical process before moraine formation. | |||
| Characteristic of this moraine is the transition of deposition layers from glaciofluvial to glaciolacustrine. Sedimentary glaciofluvial areas form the core of the Oak Ridges Moraine, though restricted to subglacial cavity fills of confined subacqueous fans. Overlaying this core is a glaciolacustrine sedimentary layer that is younger and topographically lower, principally in the ] and ] areas of the moraine. | |||
| In the late stages of its development, random unstratified accumulation (''known as ''']''''') occurred along the ice margins. Whereas the glacial river deposits were more substantial by volume, the diamicton deposits represent a greater portion of the moraine's exposed surface. Research suggests that sedimentation occurred in a west to east sequence along the four main sedimentary wedges: ''Albion'', ''Uxbridge'', ''Pontytool'' and ''Rice Lake''. The wedges may have formed in a relatively short period of time, perhaps no more than a few hundred years, as indicated by the annual deposition cycles in glacial lakes (''known as ''']s''''') within the moraine sediments. However, the lowest beds in the moraine may have experienced synchronous sedimentation. | |||
| ==Hydrology== | |||
| {{main|Hydrography of the Oak Ridges Moraine}} | |||
| A number of features comprise the hydrological system of the Oak Ridges Moraine{{ref|features}}: | |||
| * permanent and ephemeral streams, | |||
| * wetlands, | |||
| * kettle lakes and ponds, and their catchment areas, | |||
| * seepage areas and springs, and | |||
| * aquifers and other recharge areas. | |||
| This hydrological system is inter-twined with a regional flow systems not bound by the morphological limits of the moraine.{{ref|hydrology}} For this reason, environmentalists and researchers promote an aggressive protection strategy extending beyond the moraine, thus ensuring a contiguously protected hydrological system. | |||
| The preservation of aquifers is especially important, since they are used as a primary water source by some municipalities located on or near the moraine. These aquifers also discharge into tributaries that are the headwaters of creeks and rivers which eventually flow into Lake Simcoe, Lake Scugog and Lake Ontario. | |||
| 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 ], 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.{{ref|impact}} 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." | |||
| ==Research on the moraine== | |||
| In 1829, ] conducted the first investigation of the moraine.{{ref|research}} He noted the elevation, and styled the area ''Oak Ridge'', identifying the portion of moraine north of ]. It wasn't until ], in 1863, that the moraine's extent was established to be between the ] in the west, and the ] in the east. | |||
| Taylor formally defined the landform as the '''Oak Ridges Moraine''' in 1913. He described its extent to be from ] and ] in the west to the Trent River in the east. He also theorized that its origin was overlapping, interlobate glaciation retreat, between the ] and the older ]. This has become the accepted explanation for the moraine's development, though research in the ] suggested the moraine may not be interlobate. | |||
| Research conducted in the ] 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). | |||
| Current research efforts on the moraine are quite extensive. Because of the political implications of development on the moraine, and because its aquifers are a source of potable water in numerous communities, both federal and provincial governments have invested resources towards research on the moraine. The ] and ] both investigate hydrostratigraphy and hydrology throughout the moraine. | |||
| Palaeo-Indian hunter-gatherers were in this area between 10,000 - 7,000 BC. The oldest artifact found in what is now Richmond Hill, Ontario, from these people, was a stone scraper about 40 mm long, at the Mortson Site, near Leslie Street and 19th Avenue. Other artifacts were found in a settlement site on the eastern shore of Lake Wilcox. | |||
| Archaic Iroqouis artifacts circa 1800 BC have also been found at the Silver Stream site, near the headwaters of the Rouge River on Leslie Street just north of Major Mackenzie Drive, and at the Esox site, on the eastern shore of Lake Wilcox. | |||
| ==Political action== | |||
| {{main|Politics of the Oak Ridges Moraine}} | |||
| Although preservation of the moraine was first suggested in the ], it was not until 1991 that the issue achieved prominence in political discourse.{{ref|history}} | |||
| 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 ] 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 ] (OMB) in 2000. | |||
| By May 2001, with the issue still unresolved, the provincial ] 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 ] 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.''{{ref|nple}} This involved exchanging government-owned public lands in ] (the ] lands) for privately-owned lands on the Oak Ridges Moraine in Richmond Hill and ]. 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. | |||
| ==Development pressures== | |||
| The greatest threat to the function of the moraine is ] on and below its surface, particularly in the headwaters. Five million people live on or near the moraine. Use of the ] is currently under dispute; environmental groups such as the ] maintain the area's delicate ] 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 ]. However, many planners and residents see a need to preserve the moraine from the negative aspects of ]. | |||
| Moreover, because it is a rich resource of sand and gravel, it has become a significant source of materials for the ] industry of the Greater Toronto Area.{{ref|aggregate}} | |||
| ==Conservation== | |||
| Local concerns for preserving wildlife habitat on the moraine have increased in recent years. In April 2000, the ] was formed. The ORMLT is a non-profit organization that raises funds to protect areas on the moraine through ]s and outright purchases. They have protected 600 hectares (1500 acres). The ] is also active. They are raising funds to protect a 540 hectare property called Happy Valley Forest. | |||
| ==See also== | |||
| * ] | |||
| ==Notes== | |||
| # {{note|features}} | |||
| # {{note|hydrology}} | |||
| # {{note|impact}} | |||
| # {{note|research}} | |||
| # {{note|history}} | |||
| # {{note|nple}} | |||
| # {{note|aggregate}} | |||
| ==External links== | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * | |||
| ] | |||
| ] | |||