Springhill Geologic Park, Davis County, Utah
by Mark Milligan
Akin to a ghost town, intrigue and tragedy shroud this peaceful park in the Springhill area of North Salt Lake, which was created after a slow-moving landslide ultimately destroyed 18 homes over a torturous 15 years.
Homeowners were shocked to learn that their homes were located on an active landslide. Imagine finding doors that will not shut and hearing creaking and popping as the ground beneath your home incrementally inches down a gentle slope, not knowing how much deformation your house can withstand before being deemed unsafe. Unfortunately, homeowners insurance does not cover landslide damage, ultimately leaving owners with a mortgage on a nearly worthless lot. This dilemma led Springhill residents to stay as long as possible.
In the late 1990s, residents began to notice cracking and other damage, which progressed until a house on Springhill Drive was condemned in 1998. The landslide also damaged homes on Valley View Drive, Barry Circle, and Springhill Circle, but a dry period slowed movement and damage from 1999 to 2004. Unfortunately, 2005 was a wet year and movement again increased, intermittently and incrementally causing damage until five more homes were condemned by 2010. In 2012, the City of North Salt Lake, with help from partners including the Utah Geological Survey (UGS), secured a U.S. Federal Emergency Management Agency grant of nearly $2 million. That money, coupled with roughly $600,000 in matching funds from the city, was used to purchase (at full unaffected value) and demolish the 12 homes remaining on the landslide, capture and channel spring water into a stormwater drain, and create the Springhill Geologic Park, which will forever remain open space.
The Springhill landslide measures roughly 300 by 720 feet and has 150 feet of surface relief. This gentle slope likely accounts for its very slow movement. The landslide moved approximately 5 feet from the time the UGS began monitoring in 1998 to 2012 when the city began to purchase the remaining homes. The slide moved an additional 21 inches from when the park was completed in 2014 to 2020 when it was last surveyed. The UGS plans to survey the slide again in the spring of 2023.
The landslide formed in an old gravel quarry where gravels from ancient Lake Bonneville were excavated nearly down to a layer of highly weathered clay-rich volcanic ash, sand, and silt (tuffaceous rock) at the base of the landslide. This weak, poorly drained layer of clay-rich tuffaceous rock and ample groundwater likely account for the decades of recurrent creep along this gentle slope. In places the tuffaceous rock is overlain by a unit of volcanic rock fragments (the gray “volcaniclastic conglomerate” exposed at the northeast edge of the park). The Wasatch fault zone crosses the lowermost part of the slide and may have enhanced weathering and clay development by providing a prehistoric flowpath for rising deep, hot groundwater.
Springhill Drive is named for the numerous natural springs formed when groundwater easily flows downward through the Lake Bonneville gravels but is impeded by the clays and weathered rocks below, and then flows laterally along this contact until reaching the surface.
The same highly weathered tuffaceous rock unit with overlying Lake Bonneville gravels was also the culprit two-thirds of a mile to the south at the 2014 Parkway Drive landslide, the bulk of which slid down a very steep slope in one morning, destroying a single home and tennis facility.
When visiting the park, look for:
• Remnants of landscaping structures and plants from the demolished homes.
• Ground distortion—evidence of ongoing movement, especially along the northeast flank, main scarp, and toe.
• The drainage system used to capture and divert spring water off the slide in an attempt to help keep it dry and stable.
How to Get There:
Springhill Geologic Park is located just north of Eagle Ridge Drive in North Salt Lake at 191 Springhill Drive. The park can also be accessed from a trailhead at 367 East Barry Circle, which Google Street View (August 2012) still shows with a now-demolished home.
Coordinates: 40.837397° N, 111.904000° W