Needle Rock Natural Area[1] is located at the western edge of the West Elk Mountains of Colorado. The surrounding terrain is characterized by laccolithic mountains flanked by precipitous cliffs, extensive talus aprons, forested mesas, canyons, and spacious, well-watered intermontane basins.[2]Needle Rock is an intrusive plug of monzoniteporphyry[3] cropping out 3.5 miles (5.6 km) east-northeast (bearing 68°) of the Town of Crawford in Delta County, Colorado, United States. With an elevation of 7,797 feet (2,377 m),[4] the towering rock spire stands 800 feet (240 m) tall above the floor of the Smith Fork of the Gunnison River valley. The massive rock feature originated in the Oligocenegeological epoch when magmaintruded between existing sedimentary rocks[5] as the crown of a buried laccolith[3] or possibly the underlying conduit of a laccolith.[2] Subsequent erosion has exposed the prominent rock formation seen in the natural area today.
^ abNoe, D. C., and Alexander T. Klink. “OF-15-06 Geologic Map of the Crawford Quadrangle, Delta and Montrose Counties, Colorado.” Geologic, 1:24,000. Open File Report. Golden, CO: Colorado Geological Survey, 2015.
^The elevation of Needle Rock includes an adjustment of +1.473 m (+4.83 ft) from NGVD 29 to NAVD 88.
Recent Comments