Rare Phenomenon at Shuswap Falls
A rare phenomenon exists at Shuswap Falls so mysterious that geologists remain puzzled to this day. Pot-holes are rather rare geographical features found in hard-rock riverbeds.
Known to geologists as a Giant’s Kettle, Giant’s Cauldron or Pothole these cavities or holes appear to have been drilled in the surrounding rocks by eddying currents of water bearing stones, gravel and other detrital matter. Potholes vary in size and they most commonly occur in shields like the Canadian Shield, where there are ancient rocks (granite, gneiss) with different resistances to erosion. Small pebbles from these ancient rocks can be very hard and can fall into small cavities in stream bottoms and swirl, making the cavities wider and deeper. The hardness of the pebbles must be the same or higher than the rock at the bottom of stream where the kettle or pothole is forming. Where diamonds and quartz pebbles occur in the geology these hard substances can be found trapped at the bottom of potholes that they have carved. That is why these potholes are a good place to find diamonds (the hardest natural mineral on Earth).
The pot-holes at Shuswap Falls are situated in the bottom of the gorge, just below the new bridge, and are visible at low water, however they are being covered by layers of sand and silt carried by the river and deposited in the reservoir backed up by the hydro dam.
Early accounts describe four large potholes, four to six feet in diameter whose depths were difficult to determine since these early observations noted that they were almost entirely filled with sand. One had a communication cut through to the river, as its water was constantly moving. There was a log floating in it that was four feet long. Beside these there are twelve more holes of smaller diameter.
In the spillway channel a few potholes can be seen during low water flows and are present on the side of the canyon. These holes having been cut at a time when the river occupied a higher channel, before the gorge was cut. These sections are about 20 feet deep.
The illustrations of pot-holes in geological text books are usually about two feet in diameter, so the ones found at Shuswap Falls are considered singularly large. Besides it is also unusual for so many to be in one place. Thus at Shuswap Falls these pot-holes are phenomena worth more than a passing notice, however they continue to disappear from the landscape under layers of sand.
Taken from The Monashee Almanac
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