| Description: |
The Cootes Paradise study area is located in between the Dundas Valley and Hamilton Harbour, on the northwest fringe of the Hamilton-Ancaster-Dundas urban centre. This large natural area is centred on Cootes Paradise, a shallow flooded basin of open water and marsh habitat created behind the Hamilton Bar landform. The surrounding terrestrial habitat, consisting of rolling hills and ravines covered with woods and successional communities, is also included in the study area. Most of this area is publicly owned lands managed as a nature reserve and conservation education centre by the Royal Botanical Gardens (RBG).
The topography and landforms in this area demonstrate the effects of the marked variations in the water levels in the Lake Ontario basin over the past 12,000 years. The Cootes Paradise wetland is the largest remaining Great Lakes shoreline marsh at the western end of Lake Ontario. Numerous nationally and provincially significant plant and animal species occur here. Many of the plant species present in this area have not been reported elsewhere in Hamilton-Wentworth Region.
Furthermore, this large wetland is juxtaposed with the significant terrestrial habitats of the Dundas Valley and the significant aquatic habitats of the Hamilton Harbour. These three adjacent areas are hydrologically and ecologically connected and constitute an outstanding natural heritage resource situated at the apex of the highly urbanized Golden Horseshoe region. [Heagy 1993]
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| Vegetation: |
This study area is centred on a large shallow pond - wetland area, but the study area also includes the surrounding rolling uplands and ravine systems. Much of this large natural area is managed as a nature preserve by the Royal Botanical Gardens (RBG) and is the subject of ongoing biological studies. Consequently, no field work was carried out at this study area during the NAI.
The following summary of the main communities is largely based on the 1984-85 vegetation study.
Community Description:
GREAT LAKES - POND: Shallow open water pond.
Connected to Hamilton Harbour and Lake Ontario via the Desjardins Canal. Macrophyte vegetation has undergone major changes in this century due to increased sedimentation, high turbidity and destructive action of carp. Some patches of water lilies (Nymphaea odorata, Nuphar variegatum). Sago Pondweed (Potamogeton pectinatus) dominant submergent species.
GREAT LAKES - SHORELINE MARSH:
Dominated by Broadleaf Cattail in deeper water, Rough Manna Grass (Glyceria maxima) and Nodding Beggarticks (Bidens cernua) in shallower water. Formerly much more extensive, now largely restricted to protected inlets.
TERRESTRIAL - BROADLEAF UPLAND WOODS:
Red Oak, White Oak, Sugar Maple, and Red Maple dominated upland woods. (Black Cherry and American Beech are also common canopy species. Witch-hazel is the prevalent sub-canopy species.)
Manitoba Maple and Red Ash. Wet-mesic. (Common on wet-mesic soils in ravines and lowland areas.)
TERRESTRIAL - MIXED UPLAND WOODS: Oak - maple woods as above but with White Pine and Eastern Hemlock on north-facing slopes.
TERRESTRIAL - BROADLEAF FLOODPLAIN FOREST: Crack Willow - Black Willow
Other canopy species include Manitoba Maple, Red Ash, Trembling Aspen, Eastern Cottonwood. Speckled Alder and Basket Willow are present along river bank. Manna Grass is the dominant ground cover.
TERRESTRIAL - TALL SHRUB THICKET: Hawthorn, and Large-toothed Aspen - Wild Apple - Wild Pear - Hawthorn
Late successional communities.
TERRESTRIAL - OLD FIELD: Most open areas are regularly mowed.
TERRESTRIAL - CONIFEROUS PLANTATION
TERRESTRIAL - MAINTAINED SITES: Parts of this large area have been developed as a botanical garden and as parkland. An extensive trail system is present. [Heagy 1993]
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| Landform: |
Physiography and Topography:
The Cootes Paradise study area is located along the axis of the Dundas Valley buried gorge, in between the Dundas Valley and Hamilton Harbour. The central feature of this study area is the broad shallow wetland and open water pond area known as Cootes Paradise or Dundas Marsh. The waterbody is some 2 km long, and up to 1 km wide. This lagoon is separated from Hamilton Harbour by the Hamilton Bar, a baymouth bar formed in post-glacial Lake Iroquois.
This area is situated in the Iroquois Plain physiographic region and exhibits many geomorphological features which are characteristic of that region. The rolling hills and ravines which surround the central wetland were created by erosion of the sand and gravel sediments deposited in Lake Iroquois some 12,000 year b.p. The shoreline of this post-glacial lake forms a bluff which encircles the study area. The gravel bar at the eastern end of Cootes Paradise was formed as a baymouth bar in Lake Iroquois. The present lagoon is a relatively recent feature created as a result of the gradual long-term rise in the level of Lake Ontario as a result of glacial rebound. The higher lake levels have partially inundated the dissected topography west of the Hamilton Bar, resulting in the formation of the "drowned valley" landscape.
The rising level of Lake Ontario has produced similar "drowned valley" landforms at the mouth of most stream systems at the western end of the lake. However, the Cootes Paradise drowned valley is unique because of its size, and the juxtaposition of the Dundas Valley buried gorge, the Lake Iroquois bar and lagoon, and the Lake Ontario drowned valley landform. The educational and scientific value of the geomorphological features of Cootes Paradise are enhanced due to the proximity of this area to the bedrock and glacial features associated with the Dundas Valley and Spencer Gorge areas to the west, and the Lake Ontario shoreline features exhibited in the Hamilton Harbour area to the east.
Bedrock Geology:
Cootes Paradise lies immediately east of the opening of the prominent Dundas Valley re-entrant in the Niagara Escarpment. This area is situated on the axis of the deep buried bedrock gorge which extends for more than 18 km, from the head of the Dundas Valley, through Cootes Paradise and Hamilton Harbour, and under Lake Ontario. The entire study area is underlain by red shales of the Queenston Formation: bedrock outcrops only along the ravines and stranded shoreline bluff in the northern portion of the study area. The bedrock surface slopes from the north (120 to 30 m elevation) and south (60 to 30 m elevation) into the narrow ENE-trending gorge of unknown depth.
The origin of the Dundas Valley re-entrant and the associated buried gorge is controversial with various researchers attributing its formation wholly to erosion by pre-glacial and inter-glacial rivers, wholly to erosion by glacial meltwater streams, or to a combination of fluvial and glacial processes (see Kor 1991 for discussion).
Overburden Geology:
Halton Till is present in the bedrock gorge and underlies most of the study area. The till forms a plain which is generally blanketed by Lake Iroquois and Lake Ontario lacustrine sediments. Till is only locally exposed on steep banks in the northern and western portions of the study area.
Some 12,000 years before present, when drainage down the St. Lawrence Valley was still blocked by glacial ice, this area was inundated by Lake Iroquois, which occupied the Lake Ontario basin at a level some 35 m higher then the present-day Lake Ontario. The present study area formed an inlet in Lake Iroquois, extending west into the Dundas Valley re-entrant. The stranded shoreline of Lake Iroquois is marked by a fairly continuous bluff at between 105 and 110 m elevation which encircles the study area.
A large alluvial fan complex, known as the Dundas Fan, developed near the head of this inlet at the mouth of the ancestor of Spencer Creek drainage. The gravel fan slopes east, from the base of the Niagara Escarpment at Spencer Gorge to the western end of the Cootes Paradise. Much of the town of Dundas is built on this fan.
The eastern boundary of the study area follows the Burlington Heights causeway which is built on a natural, 6 km long, gravel bar known as the Hamilton Bar. The Hamilton Bar, and the associated Aldershot Bar to the northeast, formed as baymouth bars across the mouth of the Dundas Valley inlet in Lake Iroquois. These bars are similar in origin and form to the present Burlington Bar which separates Hamilton Harbour from Lake Ontario. Silty sand accumulated on the floor of the lagoon created behind the bars. The lagoon sediments formed a level plain, at about 100 m elevation, known as the Westdale Plain.
During the low water period which followed the drainage of Lake Iroquois, the Iroquoian bars and sediments were exposed to sub-aerial and fluvial process. Ancestral Spencer Creek and other streams dissected ravines into the sediments and alluvium in the former lagoon; however, the drainage apparently continued to flow around the northern end of the Hamilton Bar.
Gradual uplift of the eastern outlet of the Lake Ontario basin, amounting to some 60 metres over the last 10,000 years, has resulted in the gradual rise in the level of Lake Ontario to its present day elevation of approximately 75 metres above sea level. Water from Lake Ontario has backed up through the Harbour to behind the Hamilton Bar, creating a broad shallow pond. The lower reaches of the ravines created during the low water stage are now flooded and form inlets along the shoreline of the pond. Siltation is occurring at a rapid rate, particularly at the western end of the wetland. The naturally high rate of siltation in the flooded stream valley is exacerbated by the increased sediment loading due to agricultural and urban development in the upstream drainage area.
Soils:
The wetland/water area in the center of this area is underlain by recent sediments and muck formed in the marsh. Well-drained Grimsby sand loam and Springvale sandy loam soils have developed on the surrounding uplands except along the steep eroded ravine slopes.
Hydrogeology:
No water well data are available for this area. Regional groundwater flow patterns indicate that groundwater is flowing east towards Hamilton Harbour and Lake Ontario.
Hydrology and Surface Drainage:
Cootes Paradise is the receiving body for the Spencer Creek system as well as Borer’s Creek, Chedoke Creek, and a few other small creeks. Water flows from Cootes Paradise into Hamilton Harbour via the cut made in the Hamilton Bar for the Desjardins Canal. The water level in Cootes Paradise is directly affected by fluctuations in the level of Lake Ontario and Hamilton Harbour.
In the past, poor agricultural and urban construction practices in watershed draining into Cootes Paradise have resulted in excessive nutrient and sediment loading in the Cootes Paradise water body, which functions as a sediment trap for waters entering Hamilton Harbour.
Historically, Cootes Paradise supported a flourishing marsh community. However, the extent and quality of the aquatic and wetland vegetation in this area has undergone a dramatic decline during this century. The reasons for this decline are complex and include excessive sedimentation, excessive turbidity, the spread of non-native species, and water level changes. Feeding and spawning activities by the large Carp (Cyprinus carpio) population in this water body are believed to have played a major role in the loss of wetland vegetation. Although much reduced in extent, the marsh vegetation in this area continues to serve an important hydrological function in filtering contaminants from the surface water. The water quality and loss of wetland habitat problems in Cootes Paradise are being addressed in conjunction with the comprehensive Hamilton Harbour restoration program. [Heagy 1993]
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