Most articles and books on geology, anthropology, and history start with the early beginnings and progress chronologically to more modern times. For this article, we’ll follow suit, and begin with taking a look at Heber Valley’s geological history, with relatively late volcanic activity, faulting of the Wasatch and Uintah Mountains, Ice-Age glaciers, formation of the Heber Valley, and channeling of the Provo and other local rivers and streams. Culturally, we’ll summarize the man-made features of our environs, including the dams, reservoirs, highways, byways, and trails.
Let us begin!
Repeated ear-splitting roars of venting lava and steam preceded fast-moving mud and lava flows, shaking the valley floor, heaving like wild-water rapids, expelled from a series of volcanoes. The east-west trending chain of volcanic vents stretched along a fault corridor between what is now Park City and Oakley. Now called the Keatley Complex, this sequence of volcanic eruptions was our area’s last major violent geologic event. Geologists estimate this cataclysmic period occurred approximately 30-40 million years ago when explosive volcanic eruptions dominated this area. As they cascaded south, the speeding lava flows gathered rocks, water, and dirt, burning up trees and occasionally burying them in steaming ponds to eventually become petrified wood. Evidence of these extensive lava-mud-rock flows can be explored today in the road cuts south of the Jordanelle Reservoir between US 40 and Francis. Though the volcanic cones are gone, victims of collapse and erosion, the underground volcanic intrusions include the “Park Premiere,” a source of Park City’s precious metals. Closer to Heber City, the Mayflower mines boasted rich silver-lead-zinc-gold veins and views that are hard to beat of the Wasatch Back, Heber Valley, and west Uinta Mountains. A hodge-podge of old mining and fire roads, hiking, and biking trails, remnants of narrow-gauge railroad beds, and newer ski trails crisscross the terrain east and west of Heber Valley.
Along with the massive lava flows, the Keatley volcanic sequence also heated underground aquifers in the Wasatch Mountains. Today, remnant deep, hot rock structures heat the water that once flowed through the lower levels of the Mayflower mine tunnels, and fills our thermal spring “hot pots” in Midway, including the world-famous Homestead Crater. The crater is not a volcanic cone but the result of a slow buildup of travertine rock layers, a form of limestone associated with thermal springs. Not nearly as warm as several other hot pots in Midway, or even when it was created thousands of years ago, the Homestead Crater spring within the travertine cone, accessed via a tunnel bored through it, is a comfortable 90-92 degrees. You can and may want to get scuba-certified in Homestead Crater!
Much later, around 17,000–32,000 years ago, a gradual decrease in global temperatures and massive snowfalls froze rivers and stacked layers of ice and snow in multiple faulted valleys in the Wasatch and Uintas, shaped by ongoing uplift and faulting. In the Wasatch, beautiful Mount Timpanogos marks the western skyline — our serene Princess holds a cirque below her, the final resting place of a once mighty glacier, and still held a permanent snowfield through the early 1900s. Some still call the cirque and winter snowfield “Timp glacier” — indeed, some years find the snow remaining through summer, and perhaps some glacial ice remains at its rocky core. To our East, the Uinta valleys were home to dozens of glaciers — the longest, called Blacks Fork glacier, snaked 22 miles from its cirque in the northern Uinta Mountains. In the south, larger but somewhat shorter ribbons of ice enjoyed greater snowpacks on more gently dipping sandstone and limestone slopes. While the Keatley volcanic complex and Heber-Francis highway offer views of stacked layers of lava, mudstone, and chunky Brescia flow, Mt. Timpanogos and the Uinta Range offer views of U-shaped carved glacial valleys, cirques, and glacial boulder outwashes called moraines.
Our modern Heber Valley/Francis Road development was made possible by the damming of the Provo River by the Core of Engineers beginning in 1987. One of three major dams and reservoirs along the Provo River, the Jordanelle covered Keetley, Hailstone, and Jordanelle. Since 1993, the reservoir and surrounding shores have become part of the Jordanelle State Park, used by campers, rock climbers, anglers, boaters, windsurfers, and other land and water sports enthusiasts. From Jordanelle Dam, the Provo River resumes its flow south and west through Heber Valley, veering toward Charleston and into Deer Creek Reservoir. Above the dam, behind Coyote Ridge, snow accumulates in winter and hosts fat tire, snowshoe, and cross-country ski trails. The volcanic lava-mud-rock flows that line the road are impressive and extend south to Red Ledges and the Big Pole trail system Southeast of Heber City.
Just to the west of the Jordanelle Dam, a significant fault line generated massive rock layer uplift and separation between igneous granitic rocks of the Park City formation and sedimentary beds of limestone, sandstone, quartzite, and conglomerate deposited by ancient seas and rivers. Look for tell-tale upside-down V-shaped rock formations thrust skyward across the Wasatch Back in this area. To the East, similar faulting helped shape the uplifted Uinta foothills. Further downstream along the Provo, both glacial till, from boulders to glacier-ground sands, igneous granitic-volcanic rocks, and shattered sedimentary rock layers are found in and along the river and foothills. Importantly, flyfishing is robust and productive in this section of the Provo River, and fly-casters in waders are seen nearly year-round here! Spilling into Deer Creek Reservoir, the Provo keeps nutrients flowing to feed a variety of wildlife and open waters for fishermen. Kite surfers, boaters pulling skiers, and wake surfers enjoy the summer waters. Deer Creek Dam is the earliest remaining such structure, built in 1941 across the upper, eastern end of Provo Canyon. The Heber Valley Railroad (HVRX), or “Heber Creeper,” began as a branch line of the Denver & Rio Grande Western Railroad that connected Heber City to Provo, Utah. Now, she runs down Provo Canyon to Vivian Park, offering spectacular views of Mt. Timpanogos, Deer Creek Reservoir, Sundance Mountain Resort, and the Provo River Canyon.
As Heber Valley, Wasatch Back, and Uinta Range residents and visitors, we enjoy the best that Fire, Ice, Rock, and Man have created over the past thousands of years. And the landscape is still being shaped: The Provo River meanders and changes course both naturally, and sometimes, with our help. Resorts take advantage of the glacial valleys and cirques that now provide ski and snowboard terrain for all abilities. Dams and reservoirs provide anglers and boaters with giant, rock-lined pools to play in. Water heated from below soothes our tired bodies after a long day on our feet, riding bikes, or plunging downhill on our skis and snowboards as we negotiate numerous and expanding trails above us. We enjoy creation at its best here and are thankful for it.
1 Geologic map of the Charleston Quadrangle, Wasatch County, Utah by Robert F. Biek and Mike Lowe, 2009
2 Geologic Map of the Heber City Quadrangle, Wasatch and Summit Counties, Utah – Download. Robert F. Biek, 2022
3 “Way We Were: The era of explosive volcanoes in Park City”, Jul 17, 2020, by Sherie C. Harding, PhD, Park City Museum
4 UTAH’S GLACIAL GEOLOGY, by Bob Biek, Grant Willis, and Buck Ehler, Utah Geologic Survey, Volume 42, Number 3. September 2010
5 Wikipedia, Heber Valley Railroad, August 2022.