Antelope Isle
Antelope Island (foreground), the causeway and Great Salt Lake. and the Wasatch Range on the mainland in the background.

This is my last post from my stay at the American Industrial Hygiene Association (AIHA) conference in Salt Lake City. But, it’s really not about the conference at all, it’s about Utah’s geology or at least the small pieces of it I was able to see. After arriving in the City on Saturday I had a great visit to the Natural History Museum.  By Sunday morning I was ready to get up close to some of Utah’s fascinating environmental settings. A quick internet search brought me to the Antelope Island State Park web site, which sounded like a very good destination for the day.

Antelope Island is the largest Island in the Great Salt Lake; it’s home to a large free ranging bison herd, pronghorn antelope, big horn sheep, mule deer and other wild animals and birds. From Salt Lake City it’s a little less than an hour’s to drive to the park entrance; the island is connected to the mainland by a 7-mile causeway that runs through the lake.

The Great Salt Lake, reputed to be the largest natural lake west of the Mississippi River, is actually a small remnant of historic Lake Bonneville. At its largest, about 15,000 years ago, Lake Bonneville covered 20,000 square miles and extended into Idaho to the north and Nevada to the west; it was almost as large as modern day Lake Michigan and was much deeper. Like the Great Salt Lake, Lake Bonneville was a Terminal Lake, meaning no rivers flowed out of it, but it captured all the runoff water from the surrounding mountains.

The limits of Great Salt Lake and the larger Lake Bonneville.

Geologists think that about 15,000 years ago the elevation of Lake Bonneville rose to the level of Red Rock Pass to the north in Idaho. Once the lake reached that level, its water began flowing down through the pass to the north. The erosion of the pass caused by the rapidly moving lake water led to a catastrophic flood that resulted in most of Lake Bonneville draining into Idaho’s Snake River drainage basin. The entire event is believed to have taken less than a year. Almost 5,000 cubic kilometers of water are estimated to have inundated southern Idaho as a result of the flood.

At over 6,000 feet elevation the mountains on Antelope Island would still have towered above the surface of ancient Lake Bonneville even at its height. While on the island I hiked to one of the recommended peaks and got fabulous views of the surrounding lake and mountains. While on my way I saw numerous bison, deer and antelope. The visitor’s center has excellent displays and helpful staff; it’s a good stop to make at the start of your visit. The only downside of my island adventure were the abundant no-see-ums, they were out in force and left my legs bitten and red.

Like most of the western US, northern Utah has experienced drought conditions for the past several years. As a result the Great Salt Lake has shrunk to a fraction of its size of only a few years ago. Walking out to the lake’s surface involves a longer walk over the salt crusted beach. As I was leaving Antelope Island I stopped to ask a couple of park rangers for a recommendation on where I should spend my last free morning on the day I would be leaving Salt Lake City. Almost in one voice they answered Snowbird, a town/ski resort at the top of a canyon just south of the city.


Jutting sharply up from the eastern side of the Great Salt Lake basin is the Wasatch Range, the western-most Mountains of the greater Rockies. Looking up at the mountains from the basin one sees deep “V” shaped canyons with peaks to an elevation of 12,000 feet. Not the highest in the Rockies, but they do have some of the largest unbroken elevation rises. Of the canyons, the Big and Little Cottonwood are some of the most studied geologic features in Utah. Snowbird, the name of a town and a ski resort, sits near the top of Little Cottonwood Canyon, with the Alta ski area at virtually the very top. The Cottonwood Canyons contain some of the most dramatic glacial scenery in the Wasatch Range.

These canyons, many of their tributaries and high-elevation basins were filled with hundreds of feet of glacial ice between 30,000 and 10,000 years ago. Geologists believe that The Little Cottonwood Canyon glacier reached beyond the mouth of the canyon and extended well into Lake Bonneville, calving ice bergs into the Ice Age Lake. In contrast, the Big Cottonwood Canyon glacier, is believed to have advanced only about 5 miles down its canyon, presumably due to less snow accumulation in the canyon’s catchment area.

After my morning brew at Alchemy Coffee I set off for Little Cottonwood Canyon. I knew my visit would be brief because my flight left in the mid-afternoon. The drive from the City to the mouth of the canyon was surprisingly quick. As I turned east up the canyon road I got that sense of being in a very special place. The canyon walls rise sharply on both sides of the road and the elevation kept ascending as the road went east deeper into the canyon.

Little Cottonwood Creek
My lunch time view of Little Cottonwood Creek.

The weather was perfect, another gorgeous Utah day, so the views were spectacular in all directions. When I got to Snowbird there was still snow on the mountains, but I was told that this was residual snow from a recent storm rather than the remains winter snow-pack, of which there had been little. I meandered up a steep trail for a bit, looked at my watch, sadly turned around and walked back to my car. On the way down the canyon I stopped beside Little Cottonwood Creek to have my lunch. An hour later I approached the SLC airport ready for the trip home.

Overall I was really taken by Salt Lake City, especially with how accessible it is to spectacular environmental settings. One is hard pressed to make it through the day without panoramic views of mountains and the Salt Lake basin, you really can feel the magic in the air. It is a great destination and I hope to be going back there real soon.