| Castle Rock | |
|---|---|
 Castle Rock from Lake Chelan | |
| Highest point | |
| Elevation | 8,166 ft (2,489 m)[1] |
| Prominence | 579 ft (176 m)[1] |
| Parent peak | Flora Mountain (8,328 ft)[1] |
| Isolation | 1.0 mi (1.6 km)[1] |
| Coordinates | 48°15′27″N120°41′34″W / 48.257458°N 120.692678°W /48.257458; -120.692678[2] |
| Geography | |
  Castle Rock Location in Washington Show map of Washington (state) Castle Rock Castle Rock (the United States) Show map of the United States | |
| Country | United States |
| State | Washington |
| County | Chelan |
| Protected area | Glacier Peak Wilderness[2] |
| Parent range | North Cascades Cascade Range |
| Topo map | USGSStehekin |
| Climbing | |
| First ascent | 1917 by Geodetic Survey[3] |
| Easiest route | Scramblingclass 2-3[1] |
Castle Rock is an 8,166-foot (2,489-metre) mountain summit located on the shared border ofGlacier Peak Wilderness andLake Chelan National Recreation Area in theNorth Cascades ofWashington state.[4] The mountain is situated above the western shore ofLake Chelan inChelan County, on land managed byWenatchee National Forest. The nearest higher peak isFlora Mountain, 0.7 mi (1.1 km) to the south.[2] Precipitationrunoff from the peak drains into Lake Chelan via Castle Creek, Canyon Creek, and Bridal Veil Creek.Topographic relief is significant as the summit rises 7,066 feet (2,154 meters) above the lake in 2.5 mile (4 km).
Weather fronts originating in the Pacific Ocean travel northeast toward theCascade Mountains. As fronts approach theNorth Cascades, they are forced upward by the peaks of the Cascade Range, causing them to drop their moisture in the form of rain or snow onto the Cascades (Orographic lift). As a result, the North Cascades experiences high precipitation, especially during the winter months in the form of snowfall.[3] During winter months, weather is usually cloudy, but due to high pressure systems over the Pacific Ocean that intensify during summer months, there is often little or no cloud cover during the summer.[3]
The North Cascades feature some of the most rugged topography in theCascade Range with craggy peaks, spires, ridges, and deepglacial valleys. Geological events occurring many years ago created the diverse topography and drastic elevation changes over the Cascade Range leading to the various climate differences.
The history of the formation of the Cascade Mountains dates back millions of years ago to the lateEocene Epoch.[5] With theNorth American Plate overriding thePacific Plate, episodes ofvolcanic igneous activity persisted.[5] Glacier Peak, astratovolcano that is 21 mi (34 km) southwest of Tupshin Peak, began forming in the mid-Pleistocene.[3] In addition, small fragments of theoceanic andcontinental lithosphere calledterranes created theNorth Cascades about 50 million years ago.[5]
During thePleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris.[5] The U-shaped cross section of the river valleys is a result of recent glaciation.Uplift andfaulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the North Cascades area.
