Eastern Mojave Vegetation Colorado State Highway 93  
 

Tom Schweich  

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Literature Cited
 From Boulder to Golden.

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

Junction: State Highway 119
  Junction: State Highway 170

Other articles: Colorado State Highway 128 at CO 93  

Junction: State Highway 128, W. 120th Avenue.

Species Lists: Frasera speciosa  

One to two miles to the east is Section 3 from where there is a single collection of Frasera speciosa.

Locations: Rocky Flats.  

Rocky Flats

Rocky Flats stretch for 3 miles north to south, on the east and west sides of the highway. I have seen some references to the “Rocky Flats pediment.” However, it looks more an alluvial fan at the mouth of Coal Creek Canyon.

Locations: Rocky Flats National Wildlife Refuge.  

Rocky Flats National Wildlife Refuge

 

Other articles: Colorado Highway 72 at CO 93  

Junction: State Highway 72, west to Coal Creek Canyon.

Other articles: County Road 284 at CO 93  

Junction: W. 58th Avenue, east only, to to W. 60th Avenue

Locations: White Ranch Park.  

Junction: W. 56th Avenue, west only, to White Ranch Park.

Locations: Ramstetter Reservoir.
Full Size ImageColl. No. 1383, Linum perenne
Full Size ImageRamstetter Reservoir from slope of North Table Mountain.  

Ramstetter Reservoir east of highway.

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

Locations: North Table Mountain Park.
Full Size ImageNorth Table Mountain Trailhead  

North Table Mountain Trailhead. Access to North Table Mountain from the west side.

Other articles: Field Notes 6 Apr 2017

Locations: Golden.
Full Size ImageColorado Highway 93 and North Table Mountain.  


City of Golden below …

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

Junction: Wyoming Circle, to N. Ford Street.

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

Junction: Golden Gate Canyon Road, County Road 70

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

Junction: Washington Avenue

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

Junction: Iowa Drive, west into Mountain Ridge subdivision, east towards Washington Avenue and Iowa Street.
  Bicycle bridge crosses the highway.

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

The highway passes near the center of the NE1/4 SW1/4 Sect 28, T3S, R70W.

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.  

Cross Magpie Gulch, an informal name not recognized by the Bureau of Geographic Names.

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.

Full Size Image
Stabilized landslide near CO Hwys 58 and 93.
Full Size Image
Magpie Gulch.

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

Junction:
  • 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

  A list of all literature cited by this web site can be found in the Bibliography.
  Kirkham, Robert M. 1977. Quaternary movements on the Golden fault, Colorado. Geology. 5: 689-692. {TAS-pdf}
  Noe, David C., James M. Soule, Jeffrey L. Hynes and Karen A. Berry. 1999. Bouncing boulders, rising rivers, and sneaky soils: A primer of geologic hazards and engineering geology along Colorado's Front Range. Field Guides. 1: 1-19. Boulder, CO: Geological Society of America, 1999. {TAS-pdf}
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Date and time this article was prepared: 9/23/2017 2:32:18 PM