The Okanagan, a Place of Geological and Biological Diversity
by Richard J. Cannings, author of Roadside Nature Tours Through the Okanagan
From the moment you first see the Okanagan Valley, it is obviously a special place. Whether you descend the steep switchbacks of the Crowsnest Highway into Osoyoos or fly into Penticton past the rugged Skaha Bluffs, the valley appears completely different from its surroundings, almost un-Canadian. Its reputation often precedes it of course – Canada’s “pocket desert“, a place of great geological and biological diversity. Birders know this diversity and come from all over the continent to see the 200 species that breed in the Okanagan. There are few places of similar size in North America that could match that total, and none that would exceed it. Canadian naturalists are attracted by the long list of plants and animals found nowhere else in the country. The diversity is a product of both location—sandwiched between the coast and the prairies, between cold northern forests and Great Basin deserts—and elevation.
The Okanagan is British Columbia’s deepest interior valley, extending from the hot valley floor at 275 metres (900 feet) to alpine peaks at 2100 metres elevation (7300 feet). The valley was born millions of years ago in the collisions of continents that built the entire west coast of North America. Two hundred million years ago the west coast was somewhere between the Okanagan and Calgary; then a large piece of land known as Quesnellia slid into North America, creating much of the British Columbia interior. A second collision formed the coastal regions of the province. Then, about 55 million years ago, the collisions subsided and the monumental pressure that had been pushing eastward throughout British Columbia eased. This relaxation created deep cracks throughout the province, among them the new-born Okanagan Valley. The ancient rocks that had once been the continental shelf of North America, long buried by Quesnellia, rose to the surface. They now form the cliffs along the east side of the Okanagan, as well as the massive McIntyre Bluff that forms the west wall of the valley at the south end of Vaseux Lake.
Volcanic activity was common during the birth of the Okanagan, creating mountains throughout the central Okanagan including Knox Mountain in Kelowna, Giant’s Head in Summerland, and most of the hills around the White Lake Basin northwest of Oliver. The final geological touch in the shaping of the valley came 2 million years ago when the valley was covered by a series of ice sheets. The Pleistocene glaciers rounded off the local mountains and brought massive amounts of sand and gravel to the valley bottom.
The Okanagan lies in the rain shadow of the Cascade Mountains. Pacific storms, pushed by westerly winds, are wrung dry as they ascend the cold coastal slopes of these high peaks. As the air descends into the Okanagan, it is relatively warm and dry, and often the only local sign of a storm that brought torrential rain to Vancouver and Seattle are grey skies and a brisk southerly wind on Osoyoos Lake. As a result, the south Okanagan receives only 30 centimetres (12 inches) of precipitation each year – about the same as Tucson, Arizona. The cold Canadian winters are strongly moderated by the large lakes in the valley, and vintners needing to harvest icewine grapes at -8 °C are often forced to wait for the coldest night in January.
This warm, dry climate produces Canada’s “pocket desert”, a small area of bunchgrass, prickly pear cacti and rattlesnakes that clings to undeveloped sites in the valley bottom between Oliver and Osoyoos. The dominant shrub in this area is the antelope-brush, a gangly plant that is covered with fragrant yellow blossoms in spring. More than 30 of Canada’s species at risk occur in this area, the highest density of endangered plants and animals in the country. Fourteen species of bats are found here, more than anywhere else in Canada, including the pallid bat that hunts beetles and scorpions scuttling between the grasses, and the spotted bat, whose big pink ears catch the sonar clicks bouncing off big moths. Wildflowers abound in spring and early summer when the soil still carries moisture left by the meagre winter snowpack.
Visitors can experience this natural diversity in several short drives. Meadowlark Road climbs east of Black Sage Road in Oliver at the south end of Burrowing Owl Vineyards; at the end of the road is a small parking area and trails through native desert grasslands with a great view of Osoyoos Lake and the Okanagan River. On a hot day, the walk along the riverside trail north of Oliver makes you appreciate the special value of these water-fed woodlands. One of the most spectacular drives starts on Highway 3 west of Osoyoos. The road climbs through Wild West sagebrush country and passes Spotted Lake, a bizarre saline pond featuring hundreds of huge crystalline rings. At Richter Pass, a gravel road leaves the north side of the highway and climbs Mount Kobau. The lookout at the peak gives you an unsurpassed view of the valley far below, a gold, green and blue gem set in a sea of mountain forests.