Glad You Asked—Glacial Striations and Slickensides
Monday, November 2nd, 2009
What are those groovy rocks and how did they get that way?
by Carole McCalla
On a hike around Lake Blanche below Sundial Peak in Big Cottonwood Canyon, a group of hikers came across long, straight, parallel grooves on a smooth, polished rock surface. Recalling another location where they had seen similar features at the foot of the mountains north of downtown Salt Lake City, they wondered if these markings were formed in the same way. Indeed, what exactly are they and how were they formed?
Although the smooth, grooved surfaces at these two locations are similar, they were actually formed in very different ways.
Geologic Information: The area around Cascade Springs is underlain by coarse-grained glacial sediment deposited when glaciers covered high elevations of the Wasatch Range approximately 30,000 to 10,000 years ago.