This virtual cache highlights a very prominent landform on British Columbia's Thompson River just downstream from the historic town of Ashcroft. As access to Black Canyon relies on a combination of private First Nations reserve land roads and the active mainline right-of-way of the CNR (Canadian National Railway), an actual visit to this site is not available without special permission.
Because of large deposits of glacial silt, sand, and gravel in the lower Thompson River valley, large landslides are common. The area downstream from the town of Ashcroft is prone to landslide events; eight major events between 1880 and 1982 have been recorded. Several of them have obstructed the river, and caused large, temporary lakes. An 1880 slide caused the formation of a short-lived lake over 14 kilometers long with a maximum depth of 18 meters. These slides have caused major damage to the rail lines and farming operations in the river valley. The Black Canyon landform is the result of the 1880 landslide event. Heavy irrigation has been blamed for some of the events. [Wikipedia].
Our local newspaper, the Ashcroft-Cache Creek Journal, published the following article on February 7, 2012 written by one of our local authors, Esther Darlington MacDonald. It provides a wonderful "word picture" of this major landslide event in 1880:
The rolling hills of the Black Canyon
The canyon changed the course of the Thompson River - and possibly history.
Looking down on Black Canyon from Sundance Guest Ranch.
Before the village of Ashcroft was conceived in the eyes of an American sheepherder, Oliver Evans, as he looked over the mesas and the Thompson River, before the railroads were built on either side of the Thompson River, the silence of those vast river mesas was shattered by a thunderous explosion. It was an explosion that could be heard for miles in every direction.
That handful of early settlers at Ashcroft Manor, and their nearby neighbors, the natives now known as the Nlkapamux, or Thompson people, must have been harshly awakened the night of Oct. 14, 1880.
“What in God’s name was that?” might have been just one of the exclamations heard.
What occasioned the explosion, one never heard before in that sparsely settled region, was a landslide of gigantic proportions. Many thousands of tons of clay and gravel had shaken the walls of the Thompson River canyon and came crashing down into the River.
What happened next was a phenomenon that greatly startled and mystified travelers on the wagon road between Spences Bridge and Savona. The Thompson River had been reduced to a mere trickle.
The river was completely blocked. The barrier was created a short three miles from what was to become the village of Ashcroft. For over 40 hours, the barrier held the river’s course, and from the barrier to the mouth of the Nicola River, the dry riverbed of the Thompson was laid bare. Above the barrier, the river rose in height with deadly swiftness. The Thompson has always been a swiftly flowing river. The flat upon which the village of Ashcroft was built was covered with water to a depth of 16 inches. The flour mill that stood at the mouth of the Bonaparte River where it enters the Thompson was completely submerged. The mill had been built three years earlier by Jerome and Thaddeus Harper. The backwater reached as far upriver as Walhachin. At Yale, then a thriving town on the Fraser River, it was noted with alarm that the river had dropped between four and five feet.
When the slide barrier finally began to be released on Sunday, Oct. 17 and the silt-laden Thompson became even murkier as the river’s tributaries began to resurge into its former swiftly flowing current, debris of every kind swept passed Yale, the tsunami picking up every fence post, juniper tree, sagebrush, and tumbleweed, every stick and log of the humble dwellings alongside the river. The river at Yale rose again, flooding past its usual depth.
Meanwhile, a channel at the slide location had been dug by furiously working residents near Ashcroft. But once the river began to flow again, there was a dramatic erosion of glacial sediments left from the Miocene era. Great masses of the river canyon began to wash away, creating a deeper channel and scouring the rocks and boulders of the river bed. Within what amounted to a few hours, the Thompson River resumed its mighty course, and the land became as silent and motionless, apparently, as it had been before the slide.
Spences Bridge in 1905, on a bright warm summer's day on Aug. 13, became the scene of another, equally dramatic landslide. The banks of the Thompson created such havoc that an entire village was destroyed and lives were lost. The canoe of a native family fishing for salmon was engulfed in another tsunami-like flooding. Everyone in the boat lost their lives.
Black Canyon today is a tourist attraction. Mentioned in holiday brochures and online, the great shallow hole in the corridor of the Thompson River attracts visitors from all over the world. Inland gulls fly against the charcoal-colored cliff face, white specks against a backdrop of purplish, dark grey-blue slate-colored cliffs, the stuff of painters’ motifs, with the yellow ochre grassy plains above and around the orifice left by inexplicable forces, some might think. But are those forces so mysterious?
Could the runoff from the fields above, cultivated by the Cornwall family, have caused, after a time-lapse of over 20 years since the land was being cultivated, have something to do with the avalanche of 1880? Glacial clay is notoriously mobile. It may lie for many thousands of years, eons, in fact, harmless. But water, that everlasting necessity for any kind of cultivation, can move what seems unmovable. Ashcroft itself has had a taste of landsliding. A slide from the Mesa Vista area once actually covered the streets below and ran across the bridge. Cache Creek too, in more recent times, has experiences slides that created significant destruction.
We live in a country blessed with a climate that is not extreme, but occurrences as described in this article are very real possibilities.
Esther Darlington MacDonald
A local resident, Josh White, has also produced a wonderful YouTube video of Black Canyon and the surrounding area with his drone. If you are interested in looking at this, use this link: https://youtu.be/ymX1Y30bGTI
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TO LOG THIS CACHE:
The cache location is near the parking area but is close to a major highway including lots of industrial traffic. Carefully watch for all traffic always! Access to the cache location is on the other side of the highway barrier away from traffic but on a somewhat uneven surface near a fairly steep dropoff, so care is urged in walking to GZ. Special care should be taken if children are taking part.
To log this cache, stand at the indicated GZ coordinates and then:
Firstly, looking downriver, take a "selfie" picture of yourself, your GPS, and/or a sign with your caching name on it with Black Canyon clearly visible in the background. Send the picture to us via the Message Center feature of the geocaching.com website or app or via e-mail to mooogirl@icloud.com.
Secondly, turn to your right and take a picture of Ashcroft with the closest yellow & black "curve ahead" road sign in the foreground. Send the picture to us via the Message Center feature of the geocaching.com website or app or via e-mail to mooogirl@icloud.com.
Then, you may log the cache as usual.
If you are a train lover, this is a magnificent spot to watch one of the few places in western Canada where both the CNR and CPR mainlines run closely together!
Thank you for participating in our first-ever virtual cache!
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Virtual Rewards 3.0 - 2022-2023
This Virtual Cache is part of a limited release of Virtuals created between March 1, 2022 and March 1, 2023. Only 4,000 cache owners were given the opportunity to hide a Virtual Cache. Learn more about Virtual Rewards 3.0 on the Geocaching Blog.