In this paper I will be discussing Little Cottonwood Canyon and its rich geological history. Evident in the Little Cottonwood batholith, the Big Cottonwood formation, and the fossiliferous limestone present atop the mountain. I will touch on Lake Bonneville and how glacial ice formed the canyon and those around it. As well as the various processes going on under the noses of Salt Lake City residents.

Little Cottonwood canyon was once the sight of a great glacier atop the shores of Lake Bonneville, estimated to have existed during the Pleistocene period. (Ives, 1950)  Little Cottonwood Canyon has steep sides on either side and drains westward into the Salt Lake Valley (Laabs, et al, 2005) As the glaciers grew, the canyon deepened and Lake Bonneville expanded a canyon was born. (Laabs, et al, 2005) Eventually the glacier melted creating the canyon and its geology rich atmosphere with various sedimentary, metamorphic and igneous rocks.

The shores of Lake Bonneville are evident in the fossiliferous rocks and oolitic limestone present upper Precambrian Mineral Fork Formation. (Knolls et al, 1981). The fossils appear to have been deposited on the shorelines during the melting of the glacial ice that created the canyon. The ridges in the rocks are also evidence of the valleys being cut by glacial ice. (Knolls et al, 1981)

The most dominate of rocks throughout Little Cottonwood Canyon is the igneous intrusion stock granite seen as you travel up the canyon. Once the sight of an ancient volcano magma rose into the mountain creating pockets of granite that have since been exposed due to erosion. This granite structure throughout the canyon adds to the magnificent geology of the canyon.

Potassium Feldspar is the dominate rock in Little Cottonwood canyon dating back 26 million years old. However along the canyon you will likely find pieces of biotite, muscovite, and quartz schist, as well as some gneiss which is highest grade metamorphic rock along the canyon walls up the mountain. Atop the mountain there is also limestone and various other rocks throughout the canyon. It is this combination of rocks is that makes Little Cottonwood Canyon such a geologically rich site and so full of geologic history.

A river cuts through the canyon from the top winding down the mountain and emptying into various places such as Cottonwood Creek, and eventually the Jordan River. The snow covered mountain peaks add to this river every spring making it fill quite high and run fast. As it moves down the mountain it slowly erodes away the canyon a little at a time making it deeper and deeper every year and the river rages below the road.

The rocks of Little Cottonwood Canyon can be broken down into several rock formations with the most dominate being the little cottonwood batholith and, the big cottonwood formation. The Little Cottonwood Batholith is thought to be around 26 million years old which is made mostly of biotite crystals and potassium feldspar making up the granite that you see from the bottom all the way to the top as you drive up the road leading up to the ski resorts. The Big Cottonwood formation is made up of shale siltstone and quartzite and sits atop the Little Cottonwood formation.

As you near the peak of the mountains toward the top of the canyon the geology changes yet again, not quite as eroded away as the bottom of the mountain here you will find rocks much older like the Granodiorite dating back 33 million years, as well as fossiliferous limestone which is evidence of ancient marine life. Also evidence of marine life is the oolitic limestone found at the top of the canyon.

Evidence of mass wasting is clear on the mountain side from the defined crescent shaped scarps at the top of the mountains toward the base of the canyon. Mass wasting can also be seen on just about any hiking trail evidenced by the giant boulders that have broken off and rolled into various places throughout the canyon. She steepness of the mountain causes a relatively low angle of repose and creates mass wasting, however some this mass wasting has been caused by roadways being built (Chronic, 1996). As well as mining that has taken place in the canyon.

The base of the Wasatch Mountains is littered with fault lines evidenced by scarps created by previous earthquakes hundreds of years ago. These faults that run along the base of the canyon run along the entire Wasatch Mountains known as the Wasatch Fault System part of a bigger fault system known as the Intermountain Seismic Belt. (Stokes, 1986)

I was able to obtain quite a few rock samples along my hike in the canyon, as well as obtain pictures of many geologic events, such as frost wedging evidence from a giant split boulder, evidence of mining, and pictures of the evidence of erosion happening to the mountain exposing the granite batholith that sits beneath the surface the rest of it waiting to be uncovered by nature.

In conclusion I was able to learn about the rich geology that awaits just across the valley from me that I used to look at from my backyard. There is much to discover if you only take the time to stop and look.

Chronic, H. (1996). Rodeside Geology of Utah. Missoula, Montana: Mountain Press Publishing Company.

Ives, R. L. (1950). Glaciations in Little Cottonwood Canyon, Utah. The Scientific Monthly, 71(2), 105-117. Retrieved March 31, 2016

Knoll, A. H. (1981). Stratagraphic and Ecologic Implications of Late Precambian Microfossils from Utah. American Journal of Science, 281, 247-263. Retrieved March 31, 2016

Laabs, B. J. (2011, September). Chronology of latest Pleistocene mountain glaciation in the Western Wasatch Mountains, Utah, U.S.A. Quarternary Research. Retrieved April 1, 2016

Stokes, W. L. (1988). Geology of Utah. Salt Lake City, Utah: Utah Museum of natural History, university of Utah, & Utah Geological and Mineral Survey Department of Natrual Resources.