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This is the site of dedication for the Ophir Mill Town. To find the actual Earth Cache, turn 180 degrees and look at the Slide Mountain debris flow which has occurred.
This Earth Cache is leading you to Slide Mountain. Native American tribes have called the area of this “mountain which fell in upon itself” because of their recounts of mountain erosion in the early nineteenth century.
Because of the faults that run along the Eastern side, the Washoe Valley has been lowered considerably when compared to the Carson Range. There are a group of transverse faults that cut just East of Slide Mountain, and this has caused a very steep face. The unstable granodiorite located on this Earth Cache have a tendency to fracture when there is heavy rain, which uses water to lubricate the slope and aid in the erosion, or if there is any ground movement from nearby earthquakes. This movement proves that both of these processes have occurred and can now be seen in the debris that can be traced as far as Washoe Valley. Geologists have recorded the level of erosion going from 9,400 feet at the top of the mountain to 5,000 feet down below in the valley and there have been at least nine occurrences of this rock shedding in the past 50,000 years.
Slides from this mountain have been recorded relatively recently in the years 1852, 1862, and 1878 based on settler’s accounts. In 1890, the Prince Reservoir had its dam burst, causing a 30 foot wall of water to Ophir Creek, flooding 200 feet of railroad track and at least one house. This was believed to be caused by another mountain slide.
The most recent activity recorded about Slide Mountain occurred on May 30, 1983. The area that was disturbed included 40 to 50 acres with a very swift movement to the North half of Upper Price Lake. Because of the massive amount of debris that fell into the lake, the water overflowed into Lower Price Lake. This caused about 20 to 30 acre feet of water to be pushed into Ophir Creek. The flood took this debris, mixed with the vegetation that lined the canyon and created a very rough mixture which continued to gain velocity as it traveled down the mountain for 2.5 miles at an average speed of 18-20 MPH. Finally, the debris reached the canyon mouth and was spread across the alluvial fan, further growing the fan by its placement of new debris. The rock flow-whose maximum depth was 9 feet-continued down SR 429 until the fan’s momentum had lost speed.
Because of this flood, three homes were destroyed, one person was killed, and three were injured.
This movement was most likely caused by the oversaturization of snow packs melting that year and the fractures in the joints of the granodiorite bedrock.
The Reno-Carson City area made the best of this debris flow by mining the debris and using it to build retaining walls and to decorate yards.
To determine if you have been to this site, please email me what the largest size rock fragments moved by the debris flow are.
a) up to a foot
b) 1-2 feet
c) 2-5 feet,
d) 5-10 feet
e) 10-20 feet
Please also take picture with Ophir memorial.
For further information or to read more about Slide Mountain, refer to:
Glancy, P. A., & Bell, J. W. (1983). Landslide-induced flooding at Ophir Creek. U.S. Geological Survey Professional Paper, 16(17), 94.
and
Tingley, J. V., Pizarro, K. A., Ross, C., Purkey, B.W., & Garside, L.J. (2005). Geologic and natural history tours in the Reno area. Reno, NV: Nevada Bureau of Mines and Geology (NBMG.
Additional Hints
(Decrypt)
Qevir n yvggyr snegure gb frr zber!