The textbook geological exposures seen on the road to Panorama Mountain Village have always been readily apparent to professional geoscientists? and thanks to a new booklet published by a semi-retired geologist, those features can now be deciphered by armchair rock hounds.
“Rocks and geology are intriguing in that they are the framework upon which soil, rivers, vegetation and all living things are established,” said Mr. Benstead, whose called Panorama his part-time home for about seven years. “I’ve driven up and down the Panorama road from Invermere for years and I’m continually fascinated by the geological base and its relationship to nature and our valley’s origin.”
“One of the reasons it’s an interesting area is that the exposures along the Toby Creek Road are very good,” he added. “The road cuts up the mountain has created better exposure than you might get in other places, and there’s a sequence of four different rock formations that takes you through the later part of the pre-Cambrian period.”
The book, titled Geology of the Panorama ski hill, details half a dozen easily accessible exposures of shales, sandstones, conglomerates, and dolomites, all with parking areas nearby.
A few exposures can be found on the Panorama Mountain Village ski hill itself.
“You’ve got a variety of different rock types, and you have different structures as well; you can see big faults, you can see where one layer overrides another, and you can see big downfolds and upfolds ? synclines and anticlines,” Mr. Benstead said. “It’s a bit of a textbook that you can apply to anywhere.”
The road follows alongside Toby Creek, which also offers great rock exposures, and a series of abrupt turns in the creek bed that’s a direct result of the heavily faulted nature of the Purcell Mountains.
The semi-retired geologist was inspired to write the booklet after many a chairlift conversation in which he explained the geology of the area to fascinated listeners. Last fall, he ventured out to take a closer look, rock hammer in hand, and realized it was more complicated than it first appeared.
After consulting the University of Calgary’s geological library, he wrote the short booklet, which has been in local bookstores — The Book Bar in Invermere and Bishop’s Book Cafe in Fairmont Hot Springs — since mid-May.
Mr. Benstead also led an excursion to the area during the recent Wings Over The Rockies festival, where he outlined the story of how the pre-Cambrain Purcell Mountains were formed in the Proterozoic era, between 750 million and 600 million year ago, well before the Rockies appeared.
The sedimentary rocks of the Purcells were deposited in an intercontinental basin, in a massive lake, when partway through the Proterozoic era, an event separated Australasia from North America. This caused a pulling apart, in the zone of weakness that is now the Rocky Mountain Trench, and burying of the Purcells sediments, where over time, temperature and great pressures, the rocks were metamorphized into their current types.
The story of mountain formation in the region illustrates not just the lay of the land, but also the rich natural resources that are the source of significant tourist dollars spent in the valley.
“Then the Purcells were raised up, while the area of the Rockies turned to a large inland sea; that’s when the Rockies deposition occurs in the Cambrian: trilobites in the Burgess Shale, progressing up to reef carbonate sediments, which are the base of the Alberta oil industry,” explained Mr. Benstead.
Asked to recommend one exposure in particular in the area, Mr. Benstead suggests the public see the spot found 4.1 kilometres up the road from Lake Lillian, detailed in his booklet as Location One.
“If somebody’s going to look at one thing, there’s a parking lot there for four or five cars, and slate on top of quartzite, and a big fault where you can see a different rock sequence from one side to the other,” he said.
