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  • Two friends, Nicole and Heidi, are in their second summer of exploring and experiencing adventures around the Great Salt Lake of Utah. They report their activities in a blog, and ask guest bloggers to participate. A few weeks ago, they extended such an invitation to me. My interest actually lies with the ancestor of Great Salt Lake:

    I’m older than Nicole and Heidi but that’s not why I feel more linked to Lake Bonneville than to the Great Salt Lake! They grew up playing in the lake and, while I didn’t know it then, I was born and raised on the edge of two valleys that were once the southern-most bays of Bonneville. A basic curiosity about nearly everything led me into the teaching profession, where it proved to be a good trait, and to an interest in geological history.

    Just when I first learned about Lake Bonneville is uncertain, but any memorable information didn’t come until adulthood. After a few twists, I became a teacher, moved to Salt Lake City, where, among other things, I taught 9-year-olds the geography of Utah. Ice Age? A 20,000 square mile lake here, in what is now the desert? That’s a third of the state! Mammoths along the shore? Okay... Somehow if we could color maps showing the extent of the lake, that might make it real. As I remember, neither teacher nor students questioned these rather mind-blowing facts at the time.

    Fortunately, piece after piece of information began to fall into place. By the time I was teaching geology to 5th graders the challenge to them became, “How do we know? How can we tell there was really a lake of that size here at one time?” Once I realized the significance of that “bathtub ring”, those etched marks on the landscape, I started noticing the distinctive evidence found on the hillsides up and down the length of the state. After taking slides from a variety of locations, an understanding of how the perimeters of those Bonneville maps could have been established began to congeal in my mind. It was great fun to march the kids up to the playground atop of the hill behind our school in suburban Salt Lake City and hear the quick intake of breath as they really SAW those lake level markings on the mountainside 800 feet above the valley floor.

    Red Rock Pass was completely unknown to me before that first year teaching, and I quickly became fascinated. The essential question of what happened to Lake Bonneville is rather a major one, isn’t it? I wanted to see this drainage point and was sure there must be a significant gorge if all that water poured through it. Apocalyptic images worthy of Hollywood took roost in my mind once I heard terms like “The Great Bonneville Deluge” and “The Bonneville Flood”. I was captivated by images of water thundering north into Idaho and down onto the Snake River Plain. Years later, when I finally climbed the windblown hill about 5 miles south of Downey, Idaho and gazed down the valley from where a signboard indicated the path of the drainage, I was disappointed to say the least. Without the sign, an amateur observer could miss the clues, visible in the surroundings, of a remarkable story.

    In the summer of 2012, I find myself still adding pieces to my understanding. Red Rock Pass is situated between two mountain ranges where alluvium from each met and overlapped in the valley. As the glaciers in the mountains of Utah melted at the end of the Pleistocene Ice Age, the accumulated water finally reached the crest of the low saddle. The overflowing water cut through the unconsolidated material; within weeks 1000 cubic miles of water poured through the breach. It was a plenty catastrophic event; it just didn’t leave behind the scars I expected to see. The evidence is there, but I needed more study and exposure to recognize it. For example, experts point out the huge fields of rounded volcanic boulders - gravel melons, many of which are 3 times larger than a person - carried and deposited across southern Idaho by the rampaging water. The top 350 feet of Lake Bonneville water drained away, eventually on to the Columbia and the Pacific Ocean. One thousand years later, another major climate change led to a drop of an additional 550 feet as water slowly vanished through evaporation.

    For years, I had easily parroted the words that the Great Salt Lake is a remnant of an ancient freshwater lake. What that really means in a historical sense, what really happened, continues to be far more interesting and worthwhile to understand.

    Flash forward 14,000 years.

    On May 20, 2012 six generations of my family gathered at the cemetery of our tiny ancestral town, population 242 on a good day, to watch the annular eclipse of the sun. Three of those generations had been there for some time; it was a cemetery after all. In recent years the hard pan dirt and tumbleweeds had given way to soft, somewhat patchy grass, and we had an unobstructed view to the west across the expanse of the Escalante Valley Desert, the former Escalante arm of Lake Bonneville. This was a 4 1/2 minute event we wanted to experience here, surrounded by memories and history. I was surprised, looking at pictures taken that day, how obvious it now seems that this land was once a lake bottom.

    Making a last move with his youngest son and his new wife, my great-grandfather had gazed across that same desert 150 years before, and commented “this will never amount to anything.” I’m sure he was neither the first, nor the last, to make such a pronouncement about the dry, seemingly barren land or about the brine-filled lake left behind when Lake Bonneville exited in rather dramatic fashion through Red Rock Pass. Equally certain is that Nicole and Heidi are not the first, nor will they be the last, to appreciate the surreal beauty and diversity of life to be found around the Great Salt Lake. I am delighted with their efforts to share their experiences with the rest of us and wish them many enjoyable days on their adventure.

    **Pictures accompanying this blog, as well as several other submissions (including one on pink water and banding pelicans) can be seen at
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