This earthcache is best attempted by bicycle or car. There are three stages, plus five reference waypoints that you can explore at your leisure. Like all earthcaches, you cannot log it as found until you send me your answers to the questions near the bottom of the page.
If you drive through the neighbourhoods of Norwood and Central St. Boniface (or look at them on a map), you will observe a largely homogeneous grid pattern with one prominent exception. Beginning near the intersection of St. Mary’s Road and Taché Avenue, Enfield Crescent makes a wide arc across a dozen or so streets before fading inconspicuously into Bertrand and St. Jean Baptiste Streets, to the northeast. Long ago, this route was part of the main channel of the Red River.
As streams flow, they slowly erode the sediments that line their banks. Rivers set amidst flat terrain flow relatively slowly, resulting in a meandering course. Water flowing around a bend in the stream will move more quickly around the outside, and more slowly on the inside, because water must travel a greater distance around the outside of the bend. The faster-moving water causes the outer (“concave”) bank to erode over time, while the slower water on the inside (“convex”) bend deposits some of its sediment before completing the turn (slower-moving water cannot carry as much sediment). Over many years of eroding the outer edge and building up the inner edge, the river slowly changes course and becomes more sinuous. Eventually, the meander becomes so pronounced that the water breaches the narrow gap (“neck”) the river has created, abruptly changing the course of the stream (often during high water events). The former river channel, now abandoned by the current, is left behind as an oxbow (or oxbow lake, or billabong).
Source: Ace Geography
Due to the difference in erosion on the respective river banks, the outer bank tends to be steeper (known as a river cliff), while the inner bank is more gradual (called a slip-off slope). In straighter stretches of the river, where the water's velocity is more uniform, the banks are more similar in grade and stability.
The wetland environments that oxbows sustain store excess water in the event of storms or seasonal flooding (“high water events”). If the water level fluctuates regularly, the downstream end of the oxbow may drain back into the main river channel through a small, intermittent stream. Alternatively, if there is infrequent or negligible recharge (or if the water is manually drained), the oxbow may dry up and leave a meander scar on the land as evidence of what had once been there.
Source: McPhillips Map of Winnipeg, 1883; re-produced by Graham (2012, p. 41)
European settlement in the Winnipeg area began to increase dramatically in the 1880s. Having long since diverted to its present-day course, the Red River had left behind a marshy oxbow, which was drained to enable the more efficient expansion of St. Boniface. Although the water is long gone, evidence of the old oxbow is still visible today as contours in the urban landscape marking the former river banks. Prior to its removal, a small, intermittent creek had drained the oxbow back into the river near the present-day intersection of Taché Avenue and Rue Despins in times of higher water. (That location now hosts two city-owned structures and multiple above-ground instruments to monitor river bank stability and subterranean drainage.)
The Red River’s former course can be retraced in part, beginning at the intersection of two alleys close to Marion Street and St. Mary’s Road (NW of the posted coordinates). Your task will be to observe your surroundings and apply what you’ve learned about oxbows and river banks to orient yourself within the remnants of The Oxbow of the Red. Questions follow below.
Sources
- Ace Geography. Landforms of fluvial erosion and deposition. <http://www.coolgeography.co.uk/A-level/AQA/Year%2012/Rivers_Floods/Landforms/Landforms.htm>
- Bernhardt, D. 2018-09-02. Ghost creeks: Winnipeg buried many waterways that could have changed city’s shape. <https://www.cbc.ca/news/canada/manitoba/creeks-streams-winnipeg-history-1.4641823>
- Graham, R.M.W. 2012-03-02. The surface waters of Winnipeg: rivers, streams, ponds and wetlands 1874-1974: the cyclical history of urban land drainage. University of Manitoba. <https://mspace.lib.umanitoba.ca/handle/1993/5148>
- https://en.wikipedia.org/wiki/Oxbow_lake
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To log this earthcache as found, first e-mail me the answers to the first four questions (don’t post them in your log!). You may log it as found without hearing a response from me, but e-mails with missing or poor answers may be deleted, and the cacher notified as to the reason(s) why.
Questions
1. What can you see from the posted coordinates that suggests you’re inside a meander scar?
2. At waypoint 2 you can see the old river banks to the north and south (note how Kenny Street rises in either direction). Mark waypoints by each bank and tell me how wide the river was in this spot.
3. Cautiously observe the homes on either side of Enfield Crescent as you move to waypoint 3. Why are the homes on your right side situated higher than those on your left?
4. At waypoint 3, are you closer to the former oxbow's concave or convex bank?
5. (Optional) Observe the old river banks again, on Dollard Boulevard between Langevin and St. Jean Baptiste Streets.
6. (Optional) Describe how you think The Forks would be different today if the Red River still followed its former course.
FTF: MarcoIslandGuy, erniebertelmogrover, KURT B, Jean Déniche, Awol, JAB007, and klblue