City Creek Nature Notes – Salt Lake City

February 15, 2017

February 15th

Filed under: Black-billed magpie, Geology, Pollution — canopus56 @ 7:05 pm

Pleistocene Dream

External Link to Image

Source: Photograph of Utah Museum of Natural History Panorama by Frank De Courten. Reproduced in: Hintze, Geologic History of Utah, p. 188.

3:00 p.m.

Today, I hike not in the canyon, but to Ensign Peak, which is on the ridge between City Creek Canyon and Warms Springs on the valley floor. It overlooks the lower City Creek gorge and the grounds of the Utah State Capitol building. I am there to see how the Gambel’s oak forest on one flank of the peak recovered from a wildfire last summer (August 6th). The burned oak covers only about 100 by 100 feet and is disproportionate to the amount of smoke that I saw seen last autumn. The fire’s effect was to clean out accumulated leaf litter and brush under the oaks, thus opening the floor beneath the five foot tall scrub oaks to sunlight. Although their bases are blackened by the fire, the trees appear unharmed. Along the trail to the peak, there are the constant call of Black-billed magpies. The small valleys between Ensign Peak and the City Creek ridgeline is a refugee and breeding area for the magpies. They are not hunted here, and one allows me walk within twenty-five feet (rock throwing range), before it flies off. Reaching the peak about five-hundred feet above the valley floor, the inversion layer is well-developed and distinct. On the peak, my elevation is equal to the top of the smog bank. Later, via the internet, I look at photographs of the major cities of the world: New York City, Brasilia, London, Berlin, Moscow, Islamabad, New Dehli, Bejing, Hong Kong, Tokyo, etc. All are covered in thick layers of automobile pollution and seventy-four percent of the population of developed countries live in such cities. We are in the the Anthropocene, an informally defined but not officially recognized geologic epoch, in which humans have modified the planetary environment. Sometimes I dream what City Creek Canyon would have looked like 12,000 years ago before the end of the Pleistocene Epoch and the start of the current Holocene Era, when the first humans arrived.

I imagine that ancient humans looked down into the valley from this ancient peak and that they looked down into upper City Creek from shallow caves in the canyon’s walls near mile 1.0. The old Utah Museum of Natural History on President’s Circle of the University of Utah used to have a panorama of the imagined view from Capitol Hill looking northward during the Pleistocene (De Courten in Hintze at 188). The panorama is clearly shows Mt. Olympus, Big Cottonwood Twin Peaks and Lone Peak in the background, and the foreground is the current upper Avenues at the 11th Avenue Provo Shoreline. Some elements in the panorama are familiar extinct animals, e.g. the Wooly Mammoth and the Saber-toothed tiger. Other elements are familiar sights today: the coyote, the hawk, the Sage grouse, and the Sego lily. Missing from the panorama is lower City Creek Canyon below Bonneville Drive. That part of the canyon would not be carved out until the level of ancient Lake Bonneville precipitously dropped from its Provo Level Shoreline at 11th Avenue to its current elevation between 11,000 and 9,000 years ago. Also missing from the museum’s Pleistocene panorama are humans. Prior to 2016, the earliest evidence of human habitation in northern Utah was 9,000 years ago at Danger Cave, Tooele County, Utah (Jennings). The cave overlooked ancient shorelines of Lake Bonneville. Therefore, the omission of humans from the museum’s panorama was reasonable at the time of its painting. Twelve thousand years ago, the Clovis culture had arrived in North America and its marker, Clovis arrowhead points, have been found to the north of Salt Lake City in Oregon, Idaho, Wyoming, to the south in New Mexico, and to the west in Texas, but there were no Clovis culture sites in Utah. In 2005, Utah’s first Clovis Point was found outside of Kanab, Utah (Havnes), and in July 2016, a Clovis culture fishing camp was found in Tooele County (Shaw). If the old panorama is repainted at the new museum, humans reasonably can be added in. Perhaps my Pleistocene dream did actually occur.


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