12a: Bells Canyon Geology

June 11 2022: 3.3 miles, 1.5 miles unofficial BST. Trailforks log

Today’s hike was around Bell’s Canyon Reservoir in Sandy, one of my top two or three “backyard” trails along the entire Wasatch Front. Even though there is no sign of this currently, this trail is planned to become part of the Bonneville Shoreline Trail, but challenging gaps to the east and south mean that it may take a while. The brand new (and not quite finished) Preservation Trailhead is a great addition, with a big parking lot that represents a significant investment by Sandy City to keep up with the astronomical increase in outdoor recreation. And yet, on a very hot June day, this and the other two trailhead lots were full and overflowing.

This area is unique from the rest of the Wasatch Mountains, a lot more like Switzerland than Utah, so this was a great place to talk about science rather than trails policy. Our guest today was Dr. Ron Harris, a geology professor at BYU. Dr. Harris and I had a great conversation about the unique geology here:

  • The huge granite intrusion (30 million years ago) that makes the canyons and Lone Peak white, and was used to build the Salt Lake Temple. This intrusion also formed the rich ore veins of Alta and Bingham Canyon.
  • The Ice Age glaciers (100,000-15,000 years ago) that came further down here than anywhere else, leaving the massive moraines of giant boulders that form the bowl in which the lake sits. In fact, the Little Cottonwood Glacier likely extended well into Lake Bonneville at its height.
  • The Wasatch Fault (20 million years ago to present), with its 30 meter-high exposed scarp here created by major earthquakes as little as 1,000 years ago (yes, that means we’re due).

Even though it was relatively short, this was a great hike on a great trail that should make for a great episode!

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