|Beaver buddies on the quartz monzonite boulder indicate the path to big views|
I know this for a fact, because that’s exactly what I did while looking for the diminutive G.K. Gilbert Geologic View Park in Salt Lake City, Utah. I must have blinked because I sailed right past the entrance. I reached the intersection and knew I’d gone too far. Luckily I had my trusty Yellowstone beaver buddies along to maneuver us through a quick u–turn, navigate us across one lane of rapidly approaching traffic, and bounce us safely into the gravel parking lot.
|G.K.Gilbert Geologic View Park is at the mouth of Little Cottonwood Canyon|
Apparently, the corner of 9400 South and Wasatch Boulevard in Salt Lake City has long been well–known (among those who would know such things) for excellent examples of geologic features that enable anyone to see the rocks around them with new eyes.
Five interpretive signs provide an eyeful of geologic information. Rock formations of the Wasatch Range, scarps of the Wasatch Fault (the longest and most active fault in Utah), and deposits associated with the last glaciers to pass through these parts can easily be viewed. There is also information about ancient Lake Bonneville shorelines along with past gold mining endeavors.
Three rock formations ranging in age from 1.7 billion to 31 million years old outcrop clearly in cliffs and slopes at the mouth of Little Cottonwood Canyon across from the park. The Little Willow Formation is naturally my favorite, a swirling metamorphosed mass of quartz schist and gneiss. At 1.7 billion years old it is the oldest rock in the Salt Lake City area and is about the same age as the metamorphic rocks in the Beaver Dam Mountains of southwest Utah.
|Interpretive signs explain the geology|
The Big Cottonwood Formation is a massive layering of alternating shale/slate and quartzite beds. It would have originally been deposited in a tidal shoreline environment on top of the more ancient Little Willow rocks, somewhere around one billion to 800 million years ago.
|Image courtesy of Utah Geological Survey|
Youngest of the grouping is the Little Cottonwood stock, a 31–million–year–old intrusive igneous rock known as quartz monzonite (generally aka granite).
Several scarps of the Wasatch Fault are so obvious here that I was compelled to holler “Yikes!” and undoubtedly would have done so even if I had not been the only human at the park. Additionally, my two beaver buddies could not help but be astounded (although honestly, it doesn’t take much to impress a couple of stuffed rodents).
|A scarp of the Wasatch Fault|
There aren’t many places in the world where mid–latitude (hey, that’s us!) alpine glaciers edged up against lakes during the last Ice Age. These rivers of ice moved at glacial speed out of Wasatch Range canyons 30,000 to 10,000 years ago, extending themselves into Lake Bonneville which covered much of late Pleistocene western Utah.
Glacial scouring caused the classic U–shape of Little Cottonwood Canyon (along with other canyons of the Wasatch Range). Rock debris pushed, deposited, and eventually abandoned along the sides of a glacier is known as a lateral moraine, and it can be seen above the fault scarp. Rocks of every assorted size from gravel to boulders are scattered on hillsides and give evidence of the melting and eventual retreat of the ice.
|U–shaped valleys are carved by the movement of glaciers|
|Remnant of a lateral moraine at the mouth of Little Cottonwood Canyon|
|Glacial debris litters the hillside|
So the next time you’re in Salt Lake City and looking for something to do for an hour or so, check out this great little park with its big views. And if you have a stuffed rodent or two, bring them along – they will probably enjoy the geology!
For more information and directions, find your way to http://geology.utah.gov/surveynotes/geosights/gilbertpark.htm (my source for this adventure).