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This article was published 10/10/2020 (254 days ago), so information in it may no longer be current.
MANITOBA has its share of places to visit and sights to see, but have you ever wondered about the ancient origins of sites such as the Pembina Valley or Clay Banks Buffalo Jump?
In this series, authors Barbara Huck and Doug Whiteway explore the geological, paleontological and archeological history of some of Manitoba’s many attractions in excerpts from their book, In Search of Canada’s Ancient Heartland.
Today: the Western Escarpment
Excerpted with permission from In Search of Canada’s Ancient Heartland, by Barbara Huck and Doug Whiteway, available at independent booksellers and from the publisher, Heartland Associates (email@example.com)
On hot summer days, a deep gorge on the eastern edge of the Western Escarpment draws campers, picnickers and sun seekers to the grassy banks of McFadden Creek. Big Valley, as the locals know it, is a place where children splash in the clear, rushing water and nature lovers wander upstream in search of beavers, blue herons and white-tailed deer, always keeping a wary eye for black bears.
But how many gaze up at the steep walls of shale and think about their Cretaceous seaside beginnings? Or envision the gorge’s violent glacial unveiling? Or contemplate the people who have camped here again and again over the past 8,000 years? All of these are worth a thought, for this striking ravine is nothing less than an encyclopedia of the region.
Interspersed by deep fertile valleys, the Western Escarpment forms a high ridge along the Manitoba-Saskatchewan border from the Porcupine Hills south to Turtle Mountain and eastward along the international boundary into North Dakota (where it is known as the Pembina Escarpment). At its loftiest point — Baldy Mountain at the southeastern tip of Duck Mountain Provincial Park in west-central Manitoba — the escarpment rises 831 metres or 2,659 feet above sea level, the highest point in the province. From the viewing tower on top of Old Baldy, visitors can look south across the appropriately named Grandview Valley to Riding Mountain National Park. Though it rises between 730 and 750 metres (or between 2,350 and 2,400 feet) above sea level, Riding Mountain seems higher, for in places it rises sharply 425 metres (or 1,360 feet) above Manitoba’s central lowlands.
Getting ThereClick to Expand
The Beautiful Plains Museum in Neepawa, just north of PTH 16 (the Yellowhead Highway), is open between Victoria Day and Labour Day. To reach Big Valley, with its picnic and camping areas, follow PTH 5 north of Neepawa to PR 357 (Mountain Road). Turn west for about three kilometres or nearly two miles, then head north at the Big Valley sign for one kilometre. The road into the valley is slippery when wet. The Gorge Creek Trail is on the north side of PTH 19 about 3.5 km inside Riding Mountain National Park’s East Gate, which is accessed from PTH 5 north of Neepawa, or from Wasagaming, the park’s townsite. Pamphlets on all the park’s many trails are available at the gate or in Wasagaming.
As a result, two of the most dramatic places to view the Western Escarpment are the Gorge Creek Trail along the southeastern edge of Riding Mountain National Park and Big Valley, just to the south. In both places, the underlying rock — the thick layers of Pierre Shale — can be seen. This is a Late Cretaceous formation, created when the Western Interior Seaway invaded central North America as it slumped in response to the uplift of the Rocky Mountains along the continent’s western edge about 90 million years ago. As the continent’s centre tilted eastward, the eastern edge of the seaway moved in the same direction, creating a semi-tropical shoreline that was home to Cretaceous crocodiles and other creatures for several million years.
Both the fossilized remains of a Terminonaris specimen, locally called "Chris the Croc" and discovered just northeast of Dauphin, and "Big Bert," a 5.6-metre or 19-foot skeleton of a 92-million-year-old Terminonaris robustus unearthed from the banks of Carrot River in Saskatchewan’s Porcupine Hills were creatures of this period. In fact, if the small number of other Cretaceous crocodiles found to date in North America — in Minnesota, Kansas, Texas and Montana — were plotted (on a map), they would create an outline of the seaway’s shorelines about 90 million years ago.
The Pierre Formation, a grey, sharp-edged shale, was named by American paleontologists Fielding Bradford Meek and Ferdinand Hayden in 1862, for a layer of rock they found near Pierre, S.D. Though the same formation would be known as the Riding Mountain Formation in Canada for more than a half-century, in 1981, geologists went back to the original name. Terming it the Pierre Shale, they divided it into several layers, or members, as they are known.
In Big Valley, it is the Odanah member that can be seen on the steep valley walls of McFadden Creek. Here, the creek valley is about 60 metres or more than 190 feet deep and just 600 metres or less than 2,000 feet wide. The walls are almost cliff-like in places, but farther up the escarpment just north of Highway 357 — known locally as Mountain Road and purported to be the oldest road in the province — the McFadden Creek valley opens up to a width of 1,300 metres or more than 4,000 feet. Here, its role as a glacial spillway can clearly be seen.
Thundering out of what are now wetlands between Erickson and Onanole along PTH 10, water from glacial Lake Proven tore out of the Rolling River outlet, through the southeast section of what is now Riding Mountain National Park, and carved the McFadden Creek valley through recently deposited glacial sediments and the Odanah shale. Just south of the park, it apparently ran into a stubborn outcropping of rock, turned sharply west and then southeast, all but doubling back on itself, before roaring along the crest of the escarpment. In the process, it carved the Polonia Trench.
Several streams cascade from the spillway, including Birnie Creek, which flows year round and once provided good fishing, according to local legend. Tiny Eden Creek to the south fills in the spring and after summer storms causing floods downstream that can produce flows capable of washing out roads. Neepawa or Stoney Creek has eroded the Polonia Trench and significantly enlarged its watershed over the millennia.
Along the shorelines of each of these streams grow a cornucopia of berries and nuts. One after another during the summer months, these strawberries, raspberries, saskatoons, chokecherries, hazelnuts and rosehips ripen; for thousands of years, all were used by the hunters and gatherers who established their campsites in the creek valleys, leaving behind lithic indicators of their passing.
And each time a large storm washed valley sediments away, projectile points were borne downstream with the shale and gravel to come to rest on small fans and benches near the bottom of the escarpment. As a result, landowners on these sites have amassed remarkable collections of projectile points, in some cases creating a virtual catalogue of Western Canadian native cultures over the past 9,000 years.
Many of these artifacts, which include Plainview, Alberta, Mummy Cave, Hanna, Oxbow, McKean, Pelican Lake, Besant, Plains and Prairie side-notched points, can be seen during the late spring and summer months at the Beautiful Plains Museum in Neepawa.