GEOLOGY OF THE EAST KOOTENAY REGION

The East Kootenay region on the south-eastern edge of British Columbia is a land of colossal mountains against a clear blue sky. 

That is not strictly true, of course, as this area does see its fair share of rain and temperature extremes — but visiting in the summer every view is a postcard of mountainous terrain.

Rocks from deep within the Earth's crust underlie the entire East Kootenay region and are commonly exposed in the areas majestic mountain peaks, craggy rocky cliffs, glaciated river canyons, and rock cuts along the highways. Younger Ice Age sediments blanket much of the underlying rock.

I've been heading to the Cranbrook and Fernie area since the early 1990s. My interest is the local geology and fossil history that these rocks have to tell. I'm also drawn to the warm and welcoming locals who share a love for the land and palaeontological treasures that open a window to our ancient past.  

Cranbrook is the largest community in the region and is steeped in mining history and the opening of the west by the railway. It is also a stone's throw away from Fort Steele and the Lower Cambrian exposures of the Eager Formation. These fossil beds rival the slightly younger Burgess Shale fauna and while less varied, produce wonderful examples of olenellid trilobites and weird and wonderful arthropods nearly half a billion years old. 

Labiostria westriopi, McKay Group

The Lower Cambrian Eager Formation outcrops at a few localities close to Fort Steele, many known since the early 1920s, and up near Mount Grainger near the highway. 

Further east, the Upper Cambrian McKay Group near Tanglefoot Mountain is a palaeontological delight with fifteen known outcrops that have produced some of the best-preserved and varied trilobites in the province — many of them new species. 

The McKay Formation also includes Ordovician outcrops sprinkled in for good measure.

Other cities in the area and the routes to and from them produce other fossil fauna from Kimberley to Fernie and the district municipality of Invermere and Sparwood. This is an arid country with native grasslands and forests of semi-open fir and pine. Throughout there are a host of fossiliferous exposures from Lower Cretaceous plants to brachiopods. 

The area around Whiteswan Lake has wonderful large and showy Ordovician graptolites including Cardiograptus morsus and Pseudoclimacograptus angustifolius elongates — some of our oldest relatives. A drive down to Flathead will bring you to ammonite outcrops and you can even find Eocene fresh-water snails in the region. 

The drive from Cranbrook to Fernie is about an hour and change through the Cambrian into the Devonian which flip-flops and folds over revealing Jurassic exposures. 

Fernie Ichthyosaur Excavation, 1916

The Crowsnest Highway into Fernie follows Mutz Creek. From the highway, you can see the Fernie Group and the site along the Elk River where an ichthyosaur was excavated in 1916. 

The Fernie Formation is Jurassic. It is present in the western part of the Western Canada Sedimentary Basin in western Alberta and northeastern British Columbia. 

It takes its name from the town of Fernie, British Columbia, and was first defined by W.W. Leach in 1914. The town of Fernie is rimmed by rugged mountains tipped with Devonian marine outcrops. In essence, all these mountains are upside down with the oldest layers flipped to the top and a good 180 million years older than those they sit upon. 

Before they were mountains, these sedimentary rocks were formed as sediment collected in a shallow sea or inland basin. About 360 million years ago, the rocks that you see in Fernie today were down near the equator. They road tectonic plates, pushing northeast smashing into the coastline of what would become British Columbia. A little push here, shove there — compression and thrust faulting — and the rock was rolled over on its head — repeatedly. But that is how mountains are often formed, though not usually pushed so hard that they flip over. But still, it is a slow, relentless business. 

Cretaceous Plant Material, Fernie, BC

Within Fernie, there are small exposures of Triassic and Jurassic marine outcrops. East of the town there are Cretaceous plant sites, and of course, the Jurassic 1.4-metre Titanites occidentalis ammonite up on Coal Mountain.

The regional district's dominant landform is the Rocky Mountain Trench, which is flanked by the Purcell Mountains and the Rocky Mountains on the east and west, and includes the Columbia Valley region. The southern half of which is in the regional district — its northern half is in the Columbia-Shuswap Regional District. 

The regional district of Elk Valley in the southern Rockies is the entryway to the Crowsnest Pass and an important coal-mining area. 

Other than the Columbia and Kootenay Rivers, whose valleys shape the bottomlands of the Rocky Mountain Trench, the regional districts form the northernmost parts of the basins of the Flathead, Moyie and Yahk Rivers. 

The Moyie and Yahk are tributaries of the Kootenay, entering it in the United States, and the Flathead is a tributary of the Clark Fork into Montana.

Photo One: Tyaughton Mountain, Mckay Group taken by Dan Bowden via drone; Photo Two: Labiostria westriopi, Upper Cambrian McKay Group, Site ML (1998); John Fam Collection; Photo Three: Ichthyosaur Excavation, Fernie, British Columbia, 1916; Photo Four: Cretaceous Plant Fossils, east of Fernie towards Coal Mountain. The deeply awesome Guy Santucci as hand-model for scale.