Day 4: Badlands of the Ashcroft Area and Thompson River
Ashcroft Rills and Gullies Above the Thompson River
Day 4: Badlands of the Ashcroft Area and Thompson River
Ashcroft Rills and Gullies Above the Thompson River
Our fourth day of exploration will take place in and around the towns of Ashcroft and Cache Creek. The Ashcroft site was at one time the northernmost point on the Canadian Pacific Railway in the interior of British Columbia. It was an important shipping center and stopover for the people, freight, and supplies, which were eventually destined for the "Gold Rush Trail" leading to Barkerville and the Yukon.
The area around Ashcroft and Cache Creek has a typical badlands topography.BADLANDS TOPOGRAPHY
Badlands topography is characterized by unique features that are created only under specific geologic and climatic conditions. These features are created by the erosion of water, and to a much lesser extent wind, in a sparsely vegetated semiarid region. Instead of carving gentle hills and broad valleys, these agaents of erosion sculpt soft sedimentary rock into intricate mazes of narrow ravines, v-shaped gullies, buttes, and hoodoos.
FORMATION OF BADLANDS
In areas of badland formation the land is usually composed of alternating layers of hard and soft rocks and soil. When easily eroded material, such as clay or mud stone, is topped by more resistant material, such as sandstone, the harder horizontal layers offer some protection to the beds of soft deposits below. Uncovered layers of softer rocks or soil wash away quickly, while protected deposits form nearly vertical walls beneath the harder material.
Sequence Showing Gully Erosion and Mesa and Hoodoo Formation The primary agent of weathering and erosion is usually water. Rain in these semiarid regions often falls in sudden, heavy showers. The water moves rapdily, washing down the exposed hills, loosening grains and particles of rock. Deep gullies and channels are the result.
Hoodoos Along the Thompson River The composition of the soft clay also has an effect on the rate of erosion. Badlands clay soaks up precipitation like a sponge. As it dries, the exposed soil cracks and crumbles, leaving loose rubble several inches deep on the surface of the ground. This rubble begins to wash away immediately, often during the next severe storm. Lack of dense ground cover or heavy vegetation means there are no root systems to hold the soil and impede erosion.
Bonaparte Valley and Elephant Mountain to Left Showing the Lack of Vegetation
After a full morning of exploration and lunch, we will turn back towards the Okanagan Valley. We will be travelling along the Trans Canada Highway 1 south from Cache Creek for 47 kilometers. We will then turn east along Highway 8 for 68 km from Spences Bridge to Merrit and then back east along Highway 97C for 70 km to our second stop. After this brief stop we will continue on to Westbank where we will turn south to Penticton along Highway 97, a further 45 kilometers. We will stop in Penticton for a well deserved rest. This will be our overnight stop for the next two nights.Our drive today should be about two 2 1/2 hours. (This is the longest drive of the trip).
Stop 1: Explore the hoodoos of Ashcroft area and Thompson River
Stop 2: Glacial Till and Columnar Jointing in Andesite along Coquihalla Connector
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