Wednesday 14 November 2018

ISAAC LAKE: BOWRON CIRCUIT

It is day four of our holiday, with two days driving up from Vancouver to Cache Creek, past the Eocene insect and plant site at McAbee, the well-bedded Permian limestone near Marble Canyon and onto Bowron Provincial Park, a geologic gem near the gold rush town of Barkerville.

The initial draw for me, given that collecting in a provincial park is forbidden and all collecting close at hand outside the park appears to amount to a handful of crushed crinoid bits and a few conodonts, was the gorgeous natural scenery and a broad range of species extant. 

It was also the proposition of padding the Bowron Canoe Circuit, a 149,207-hectare geologic wonderland, where a fortuitous combination of plate tectonics and glacial erosion have carved an unusual 116-kilometre near-continuous rectangular circuit of lakes, streams and rivers bound on all sides by snowcapped mountains. From all descriptions, something like heaven.

The east and south sides of the route are bound by the imposing white peaks of the Cariboo Mountains, the northern boundary of the Interior wet belt, rising up across the Rocky Mountain Trench, and the Isaac Formation, the oldest of seven formations that make up the Cariboo Group (Struik, 1988). 

Some 270 million-plus years ago, had one wanted to buy waterfront property in what is now British Columbia, you’d be looking somewhere between Prince George and the Alberta border. The rest of the province had yet to arrive but would be made up of over twenty major terranes from around the Pacific. The rock that would eventually become the Cariboo Mountains and form the lakes and valleys of Bowron was far out in the Pacific Ocean, down near the equator.

With tectonic shifting, these rocks drifted north-eastward, riding their continental plate, until they collided with and joined the Cordillera in what is now British Columbia. Continued pressure and volcanic activity helped create the tremendous slopes of the Cariboo Range we see today with repeated bouts of glaciation during the Pleistocene carving their final shape.