Other articles: Broadway at Canyon CO Highway 119 at CO 93S  

Other articles: Colorado State Highway 128 at CO 93  

Locations: Rocky Flats.  

Rocky Flats

Locations: Rocky Flats National Wildlife Refuge.  

Rocky Flats National Wildlife Refuge

Other articles: Colorado Highway 72 at CO 93  

Other articles: Field Notes 28 Mar 2019

Locations: Ralston Dike.
The Ralston Dike, or what is left of it.  

Other articles: County Road 284 at CO 93  

Other articles: W. 56th Avenue at CO 93

Locations: White Ranch Park.  

Locations: Ramstetter Reservoir.
Coll. No. 1383, Linum perenne
Ramstetter Reservoir from slope of North Table Mountain.  

Other articles: Golden Checklist Flora dev. trlhds. North Table Loop at N Table Mtn

Locations: North Table Mountain Park.
North Table Mountain Trailhead  

Other articles: Field Notes 6 Apr 2017

Locations: Golden.
Colorado Highway 93 and North Table Mountain.  

Other articles: Ford Street at CO 93 Pine Ridge Road at CO 93  

• Wyoming Circle, east to N. Ford Street.
• Pine Ridge Road, west and north, ultimately to White Ranch Open Space Park, east entrance.

Other articles: Tucker Gulch Trail at CO 93 Golden Gate Canyon Road at CO 93
Mouth of Golden Gate Canyon, source of Tucker Gulch.  

Other articles: Washington Avenue at CO 93 Field Notes 8 Oct 2014
Intersection of Washington Avenue with Colorado Highway 93  

Other articles: Iowa Street at CO 93 Field Notes 8 Oct 2014
Intersection of Iowa Drive with Colorado Highway 93  

Literature Cited:
- Kirkham, Robert M., 1977.  

Somewhere in this quarter-quarter section are the locations of two trenches dug to explore a small graben of Quaternary age, thought to be related to the Golden fault. Excavations revealed a complex geologic picture suggesting two periods of fault rupture with a total of 5.5 m of displacement. Dating of zircons and glass shards from an ash deposited in the graben and disrupted by faulting yielded dates of 0.6 to 0.7 million years, suggesting faulting occurred more recently than those dates (Kirkham, 1977).

Literature Cited:
- Noe, David C., James M. Soule, Jeffrey L. Hynes and Karen A. Berry, 1999.

Other articles: Field Notes 17 Aug 2014

Locations: Magpie Gulch.  

Stabilized landslide near CO Hwys 58 and 93.	Magpie Gulch.

Field Trip Stop 14 — Highway 6-58-93 Junction — of Noe, et al. (1999) illustrates the Golden Fault, associated landslide hazards, mitigation of landslide hazards, and the short public memory.

Looking to the north and south, we can see the distinctive hogback of the Dakota Sandstone at both ends of the valley. But why is this hogback missing at the valley center? The answer is that the Golden Fault, a large, Laramide thrust fault, weaves along the valley just to the east of the mountain front. Here, the fault has displaced nearly 8,000 feet of the Paleozoic and Mesozoic, sedimentary section (Van Horn, 1976). The trace of the fault can be seen as it cuts up the side of the first large alluvial terrace to the south of Clear Creek. There is a distinct break in the vegetation between the Fountain Formation to the west (covered with mountain mahogany shrubs) and the Pierre Shale to the east (covered with grasses).

Looking directly west, we see a road cut for State Highway 93. This portion of the highway was first constructed in 1991. A small landslide formed in the west (opposite) face of the cut shortly thereafter, and the resulting toe bulge closed the southbound lanes of the new highway. Within a year, the landslide had developed a rim of head scarps with up to 12 feet of vertical slippage, and had captured the surface flow of a small stream in Magpie Gulch. Early efforts to drain the landslide were unsuccessful. A full geologic investigation subsequently revealed that the landslide sits directly atop the Golden Fault, with low-permeability Pierre Shale on the eastern side and a wedge of fractured, permeable Fountain Formation on the western side. In 1994, three lines of rock anchors (about 40 anchors in total) were installed across the landslide. The Magpie Gulch stream was piped across the head scarps, longer horizontal drains were installed, and a remote data-logging unit was set up. To date, this mitigative effort appears to have been successful. The combined maintenance and mitigation operations for this incident are reported to have cost about 3 million dollars.

The houses to the north of the landslide were built shortly after the landslide was mitigated and all signs of its existence had been “erased” from view. One can only imagine the concern of these residents had the landslide been active a few years later. This is a good illustration of the often short-term public memory of geologic hazards.

Other articles: CO Hwy 58 at US 6 U. S. Highway 6 at CO 58  

• US Highway 6, either east through Denver, or west to US I-70 and Bishop, California.
• State Highway 58, east to US I-70 east and Denver.

Literature Cited

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Date and time this article was prepared: 11/21/2019 3:55:52 PM