Rocky Mountain Trench

The Rocky Mountain Trench, also known as the Valley of a Thousand Peaks or simply the Trench, is a large valley on the western side of the northern part of North America's Rocky Mountains. The Trench is both visually and cartographically a striking physiographic feature extending approximately from Flathead Lake, Montana, to the Liard River, just south of the British Columbia–Yukon border near Watson Lake, Yukon. The trench bottom is wide and is above sea level. The general orientation of the Trench is an almost straight 150/330° geographic north vector and has become convenient as a visual guide for aviators heading north or south.

Although some of its topography has been carved into U-shaped glacial valleys, it is primarily a byproduct of geologic faulting. The Trench separates the Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains on its west. It also skirts part of the McGregor Plateau area of the Nechako Plateau sub-area of the Interior Plateau of British Columbia. It is up to wide, if measured peak-to-peak, and varies in valley relief, but is clearly visible by air and satellite/remote sensing and is easily discernible to those ascending any of the mountains or ridges lining it.

The Trench is drained by four major river basins: the Columbia, Fraser, Peace and Liard. Two reservoirs of the Columbia River Treaty fill much of its length today - Lake Koocanusa and Lake Kinbasket. A further British Columbia power initiative created Lake Williston. Rivers that follow the Trench, at least in part, are the Kootenay River, the Columbia River, the Canoe River, the Flathead River, the Fraser River, the Parsnip River, the Finlay River, the Fox River, and the Kechika River. The North Fork of the Flathead River, flowing into Flathead Lake with the other branches of the Flathead River, is part of the Columbia River system. The Kechika is part of the Liard River system, and the Fox, Parsnip and Finlay Rivers are part of the Peace River system. The Canoe River is a short tributary of the Columbia system, draining into Kinbasket Lake, a reservoir on the Columbia River. The Kootenai River, however, does not fully follow the Trench but exits Canada southwest via Lake Koocanusa reservoir to the Libby Dam. The Kootenay River (Canadian spelling) is a tributary of the Columbia, joining the Columbia at Castlegar, BC after a meander through the United States as the Kootenai River (US spelling).

For convenience the Rocky Mountain Trench may be divided into two sections, the Northern Trench (between the Muskwa Ranges and Interior Mountains) and the Southern Trench (between the Continental Ranges and Columbia Mountains), separated by the northeastern portion of the Interior Plateau west of the Hart Ranges. The Copley Range of the Arctic Pacific Lakes Provincial Park forms the drainage divide between the northerly Parsnip-Finlay-Peace system into the Arctic Ocean (via the Mackenzie River) and the southwesterly McGregor-Fraser system into the Pacific Ocean. The northern end of the Columbia Mountains at ~54°N near Prince George, British Columbia, where the Fraser River leaves the Trench to enter the Interior Plateau, may be used for this purpose. The northern portion of the Trench is dominated by strike-slip faulting, while the southern part of the Trench was created by normal faults. Despite differences in timing and faulting styles of the northern and southern portions, they were aligned with each other because faulting for both was controlled by a pre-existing, west-facing, deep basement ramp with over of vertical offset.

Northern Rocky Mountain Trench

The Northern Rocky Mountain Trench is closely aligned with the Tintina Trench near the British Columbia-Yukon border at 60 degrees north latitude, and the two trenches could arguably be classified as one and the same - or 'extensions' of each other. The Tintina Trench extends further north-westward through the Yukon into Alaska. The visible expression of the two trenches is lost where they plunge under the boreal forests of the Liard Plain proximate to the small communities of Watson Lake, Yukon and Lower Post, BC. The highest point in the northern Trench is Sifton Pass at an elevation of about near the bend of Scarcity Creek.

Geology

Right-lateral strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench may have begun during the middle Jurassic. The fastest rates of slip probably occurred during two pulses in the middle Cretaceous and early Cenozoic, respectively, with the latter probably occurring during the Eocene. Between to over of total right-lateral movement has occurred, of which of offset has occurred since the mid-Cretaceous. The result is that terrains to the west of the fault system have moved toward the north. In the context of plate tectonics, strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench is also related to strike-slip movement along the San Andreas Fault, the extension of the Basin and Range Province, and other extensional or strike-slip fault systems in western North America. The Tintina Fault is one of the two major fault zones paralleling the Northern Cordilleran Volcanic Province, the other being the Denali Fault in the Yukon, the U.S. state of Alaska and along the British Columbia Coast.

History and accessibility

First Nations have traditionally always travelled the northern Trench. There are several post-European contact travels up the northern Trench - often of large proportion. The Trench here remains mostly wild, and the northern is essentially without roads, excepting a few cat trails for fire, outfitters, or logging. It is due to several turns of fate, and strategic administrative decisions since 1824, that the most natural land transportation corridor in northern British Columbia has been left in a wild state. On many government maps produced since 1897, indications of a passable trail have been published. However, with changes in the terrain caused by beaver dams or forest fires, and despite maintenance by guide-outfitters, the trail from Fox Lake north is often hard to find, or obliterated to all but indigenous and experienced Kaska natives. It may be more commonly used as an aviation route today.

The northern trench from the Highway 97 bridge on the Parsnip River has routes on both sides of Williston Lake to Fort Ware. The route up the east side cannot be followed due to the Peace Reach of the reservoir. The road traveler will use the gravel road up the west side of the Reservoir to Ware. Beyond that point the northbound traveller will only find a narrow cat guard (a cat guard is a primitive road constructed as a fire guard by heavy equipment-usually a bulldozer-to prevent the spread of a forest fire by creating a fuel free perimeter) for a few kilometres.

The Kaska Dena culture of Fort Ware and Lower Post refer to their ancestral use of the natural route as The Trail of The Ancient Ones. They also call it the Davie Trail honoring David Braconnier, the founding chief of the community at Ware (Fort Ware - originally called Kwadacha which the HBC named Whitewater Post)

1797 - John Finlay records the forks of the Finlay and Parsnip Rivers and ventures part way up each river. The Finlay River later comes to bear his name.

1823 to 1825 - Samuel Black was sent by the HBC north through Finlay Forks to The Fox River (Kwadacha) and returned later that season. He narrowly missed being the first white person to go all the way up the Northern Trench to the Liard River but chose not to listen to his guide - heading north westward seeking the source of the Finlay River instead. He travels far enough NW to discover the headwaters of another Trench tributary - The Turnagain River. Natives there find a marker left by Black and report it to historic Fort Halkett on the Liard River


1831 - John Macleod of the HBC records the mouth of the Kechika River emptying out of the northern end of the Trench into the Liard near the BC-Yukon border.

1872 - Capt. William F. Butler ascends part of the Finlay River and records both the Fox River and Fox Lake to the north (Ft. Ware / Kwadacha was not yet established.)

1897 to 1898 – The Canadian government sends a police patrol under Inspector Moodie to map a possible supply route from the Peace River to the Yukon - specifically Dawson City. The patrol, assumed to have perished, eventually arrived at Fort Selkirk. They proved the viability of the route and produced a surviving map of it. (Yukon Archives)

1898 – McGregor's book ''The Klondike Rush Though Edmonton'' summarizes various sources (papers) saying up to 45 parties were reported along the route from Fox River to Sylvestre's Landing. There was also a reported drive of cattle on this route (echoed in Moodie's reports and in Kaska oral history.)

1906 – A North West Mounted Police patrol under field supervision of Inspector Constantine began the construction of the Police Trail westward from Hudson Hope and then northward up the Northern Trench from HBC's post at Fort Graham.

1907 - British Columbia Premier R. McBride intervened and asked Canada to direct the police resources to connect with the more westerly Telegraph Trail route. Under protest, the NWMP field team did so. That trail was soon abandoned due to its non-viable character. The political route departure from Fort Graham westward added 400 rugged snowy kilometres to the total distance without going any favorable ground or measurable distance closer to the north. The Davie Trail is noted to be excellent for wintering horse due to low snow accumulations.

1912 - British Columbia Magazine - prospector Bower reports Sifton Pass as the most eventual and most practicable for a railway form the Fraser River to the Yukon.

1914 - Premier McBride advocates a railway on Insp. Moodie's route according to B. Kenelly in a pamphlet 'The British Columbia Peace. Fort St John' 1936.

1926 - Whitewater Post is established by HBC. Whitewater is the translation of Kwadacha, a nearby river.

1930 to 1931 - British Columbia Department of Public Works investigates a road route over Sifton Pass.

1934 - Charles Bedaux, a noted international workplace management consultant (time and motion studies) leads and finances the Bedaux Expedition - formally known as the Bedaux Canadian Subarctic Expedition. While his advance scouts arrive at McDame Post near Good Hope Lake, the leader and entourage abandon their mission at Driftpile Creek due to fatigue, lack of horse feed, and impending winter. The controversial adventure is the subject of a 1995 Bedaux film biography titled Champagne Safari.

1942 - February a final decision was reached regarding the A, B, and C routes for a northern Highway. It will connect the North West Staging Route airfields and bypass the Northern Trench for the joint Canada-Alaska Highway Alcan Highway