City Creek Nature Notes – Salt Lake City

January 3, 2017

January 2nd

Filed under: Duck, Flood retention pond, Geology, People — canopus56 @ 5:39 pm

A Bend in the Road

5:30 p.m. At the flood retention pond, the two ducks are asleep while floating. They are completely motionless and have turned their necks to lay their heads on their backs. As I start up the canyon, eight hunters are loading into their cars, and the watershed patrol person is bringing another four out in the back of the city truck. None have a taken an elk. There are only three or four persons on road and shortly, I am alone at milepost 1.5 enjoying the quiet depths of winter in the fading light. I am looking down at the mouth of Pleasant Valley, and about a quarter-mile below it, canyon bends and turns about forty-five degrees in a southeasterly direction.

Gravity pulls water straight downhill, and for many of the canyons of the Wasatch Front Mountain Range, canyons erode in almost straight lines from the ridgelines to the valley floor. If there is a bend in a canyon’s descent, this may signify a hidden geologic fault line. Examples include Elbow Fork in nearby Millcreek Canyon and Storm Mountain in Big Cottonwood Canyon. At the red bridge below milepost 1.0, City Creek Canyon bends twenty-two degrees around a curve from a north-east direction to a north east-easterly direction and then opens into Pleasant Valley.

Van Horn and Crittenden’s 1987 geologic map of the area explains why the bend in City Creek occurs. The Pleasant Valley fault line runs due north-south through milepost 1.0 and the north-west massif where the canyon opens into Pleasant Valley. One can see the effect of the fault at red bridge and mile 0.9. The sandstone layers on the south and north canyon walls are horizontal, but at Chimney Rock above the red bridge (Dec. 24th), the layer has been rotated to a 90 degree vertical angle. The Pleasant Valley Fault continues along the south-east side of the creek, but on the west side at mile 0.5, sandstone conglomerate Shark Fin Rock (Nov. 23rd) is similarly rotated to the vertical.

The fault continues down-canyon, exits and then turns east at the foothills, and there it dissipates. But a quarter mile south, at the Morris Reservoir tanks, another fault that is hidden below the surface – the City Cemetery Fault – begins. It continues traveling east along the 11th Avenue bench; and, then the fault turns due north, becomes visible at the surface, and meets Little Twin Peaks on the Avenues ridgeline. There the City Cemetery Fault turns due east and runs between the two peaks. The Cemetery Fault is why the two peaks are there. Each peak sits on the other side of the fault. Next, the fault runs south for a few hundred feet before it ends, and this marks the north east corner of the city with giant geologic question mark. The Pleasant Valley fault is not active, but it is why City Creek stream makes the shape of a boot, and geologically speaking, it kicks the City in its proverbial northeast end.

In Thoreau’s “Journal” on January 2nd, 1854, he notes pink light falling on snow and a blue light in the shadows of snow. January 2nd, 1854, he notes that the colors of winter sunsets are enhanced by ice crystals in the atmosphere. On January 2nd, 1853, he describes the beauty of the oak forest covered with a heavy snow and with ice. On January 2, 1841, he describes a fox traversing a snow covered pond.

On January 2nd, 1937, the Salt Lake Telegram reported that the Utah Audubon Society will at its monthly meeting, the results of its Christmas bird count, and that later in the month, Society will have a field trip up City Creek Canyon. On January 2nd, 1916, the Salt Lake Tribune reported on progress towards projects built using proceeds of a 1914 bond issue to deliver enough water to the City to support 600,000 people. Those projects include the Lake Mary and Lake Phoebe dams in Big Cottonwood Canyon and a 5,000,000 gallon distribution reservoir at Pleasant Valley in City Creek Canyon. On January 2nd, 1910, the City reported that it receives 10,000,000 gallons of drinking water from City Creek Canyon.

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