| Paradox Valley | |
|---|---|
 Paradox Valley as seen from near the southwest rim. The Dolores River is at the left edge. | |
  Paradox Valley Location of Paradox Valley within Colorado | |
| Floor elevation | 4,944 ft (1,507 m) |
| Length | 25 miles (40 km) NW-SE |
| Width | 3 to 5 miles (4.8 to 8.0 km) |
| Geography | |
| Location | Montrose County,Colorado, United States |
| Coordinates | 38°19′N108°51′W / 38.317°N 108.850°W /38.317; -108.850 |
Paradox Valley is abasin located in westernMontrose County in theU.S. state ofColorado. The dry, sparsely populated valley is named after the apparentlyparadoxical course of theDolores River—instead of flowing down the length of the valley, the river cuts across the middle and through the sheer walls of large mesas on either side.[1] The valley is the site of aBureau of Reclamationsalinity-control project which has caused thousands of earthquakes,[2] and is the proposed location of a newuraniummill which would be the first built in the United States in over 25 years.[3]
Paradox Valley trends northwest-southeast and measures about 3 to 5 miles (5 to 8 km) wide and 25 miles (40 km) long.[4] It lies along the extreme western edge ofColorado, close to the border withUtah, about 50 miles (80 km) south of the city ofGrand Junction. TheLa Sal Range rises just to the northwest in Utah.State Highway 90 follows Paradox Valley on its way fromNaturita to the Utah state line, crossing theDolores River Bridge near the small unincorporated town ofBedrock. The town ofParadox lies a few miles north of the highway. Elevations on the valley floor range from about 5,000 feet (1,500 m) at the Dolores River to nearly 6,000 feet (1,800 m) at the southeast end. Steep parallelsandstone andshale[4] walls bound the valley to the northeast and southwest.
The valley was named in 1875 by geologist and surveyorAlbert Charles Peale[1] after he noted that theDolores River had a "desire to perform strange and unexpected things" in the area.[5] Instead of flowing down the valley'sthalweg, the river emerges from a narrow gap in one wall, cuts perpendicularly across the mostly level valley floor, and exits through another gap in the opposite wall. As a consequence of this unusual geography, the valley cannot be easilyirrigated by the Dolores River, but springs and streams fed by snowmelt from the La Sal Range supportfarming in the northwestern third of the valley.[6]
Near the center of the valley, the town of Bedrock experiences average highs ranging from 45 °F (7 °C) in December to 96 °F (36 °C) in July. Average lows range from 13 °F (−11 °C) in December to 54 °F (12 °C) in July. An average of 11 inches (28 cm) of precipitation, including 9 inches (23 cm) of snow, fall annually at Bedrock.[7]
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The apparentparadox of Paradox Valley can be explained bysalt tectonics. The valley is a collapsedanticline, a type ofgeological fold. About 300 million years ago, during the middlePennsylvanian period, when the Dolores River was already in existence, high pressures on lands to the northeast caused underlyingsalt deposits to flow towards where the valley is today. The salt encountered a buriedfault-block ridge and was deflected upwards, penetrating the overlying rockstrata and forming asalt dome. The salt may not have actually been exposed on the surface, but groundwater entering the top of the dome dissolved the underlying salt beds, allowing the center to collapse, forming what is today Paradox Valley. This process took place over about 150 million years, a long enough time for the Dolores River todowncut into the land andmaintain its ancient course. The same process also created the Moab Valley (Spanish Valley) to the west, itself cut crosswise in a similar fashion by theColorado River.[8]
TheParadox Formation, ageological formation containingsalt,gypsum,anhydrite,shale,sandstone, andlimestone,[9] is named after exposures found in Paradox Valley. TheParadox Basin, ageologic province throughout which the Paradox Formation is found, also bears the name of the valley.[8]
Paradox Valley was within the historical domain of theUte tribe.[10] An 1868 treaty created areservation for the Utes over much of western Colorado, including Paradox Valley.[10] Squatters began grazingcattle in the valley as early as 1877, in violation of the treaty.[11] By 1881, the Utes had been forced out of the area, and in 1882 theUnited States Congress officially opened the land to settlement.[11] Springs and streams allowed farming in the northwest end of the valley, and the mid-1890s discovery ofcopper at the future site of theCashin Mine near the town of Bedrock brought in a further influx of settlers.[12] The valley and the surrounding plateau soon also became an important source ofradioactive materials, includingradium anduranium. In 1913,The New York Times identifiedcarnotite mines near Paradox Valley as the source of "the greatest radium ore deposits in the world".[13] Production of radium ceased in 1922 when richer deposits were found in theBelgian Congo, but production of uranium andvanadium continued throughout most of the century.[6]
Near-surfacesalt beds up to 14,000 feet (4,300 m) thick still underlie Paradox Valley. The Dolores River, a tributary of theColorado River, naturally picks up about 100,000[4]-200,000[14] tons of salt annually on its way through the valley.[4] In the 1980s, theUnited States Bureau of Reclamation began construction of a pumping facility known as the Paradox Valley Unit.[14] The PVU, a part of the widerColorado River Basin Salinity Control Project, became fully operational in 1996 and collectssalinegroundwater from 12 shallow wells along the Dolores River. The system then dilutes thebrine with water and acorrosion inhibitor and transports it to a high-pressureinjection well, where it is deposited 14,000 to 16,000 feet (4,300 to 4,900 m) deep intoPrecambrian andPaleozoic rocks. A 2001 study found that the total salt reaching the Dolores had declined by about 90%, although this may have been the result of a period of low precipitation during the measurement period.[4] As of 2009, the PVU removes about 113,000 tons of salt annually from Paradox Valley.[14]
The injection well of the Paradox Valley Unit hasinduced thousands ofearthquakes, including at least 4,000 prior to the year 2001.[15] Most were below the threshold of human detection, but at least 15 have been over 2.5 inmagnitude, the largest being a 4.3 magnitude quake on May 27, 2000. The PVU suspended operations for 28 days following this quake, but later resumed injections at a lower rate.[2] Further earthquakes have been linked with the operation, including a 3.9 magnitude quake in 2004.[16]
In 2009 Energy Fuels Resources Corporation, a subsidiary ofToronto-based Energy Fuels Incorporated, proposed the construction of auraniummill in the southeast end of Paradox Valley.[3] Called the Piñon Ridge Mill, it would have been capable of processing 500 tons ofuranium ore per day.[3] Legal action tied up the project for many years,[17] and as of September 2020 the project appears to have died.[18]
{{cite news}}: CS1 maint: bot: original URL status unknown (link)Municipalities and communities ofMontrose County, Colorado,United States | ||
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