Johnson Mountain (Washington)

Johnson Mountain
Johnson Mountain seen from Pilot Ridge
Highest point
Elevation	6,721 ft (2,049 m)
Prominence	1,241 ft (378 m)
Parent peak	Whittier Peak
Isolation	3.31 mi (5.33 km)
Coordinates	47°59′42″N 121°10′21″W
Geography
Johnson Mountain Location in Washington Johnson Mountain Location in the United States
Interactive map of Johnson Mountain
Country	United States
State	Washington
County	Snohomish
Protected area	Glacier Peak Wilderness
Parent range	Cascade Range
Topo map	USGS Benchmark Mountain
Geology
Rock age	Late Cretaceous
Rock type	Migmatitic Gneiss
Climbing
Easiest route	Hiking trail

Johnson Mountain is a 6,721-foot (2,049-metre) mountain summit located in the Glacier Peak Wilderness of the North Cascades in Washington state. The mountain is situated in eastern Snohomish County, in the Mt. Baker-Snoqualmie National Forest. The nearest higher peak is White Mountain, 3.3 mi (5.3 km) to the northeast, along with Indian Head Peak 3.38 mi (5.44 km) to the east. Precipitation runoff from the mountain drains into tributaries of the Sauk River. The mountain's name honors Mackinaw Johnson, a prospector who had a cabin in the vicinity.

Geology

The North Cascades feature some of the most rugged topography in the Cascade Range with craggy peaks, spires, ridges, and deep glacial 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 late Eocene Epoch. With the North American Plate overriding the Pacific Plate, episodes of volcanic igneous activity persisted. Glacier Peak, a stratovolcano that is 8.52 mi (13.71 km) north of Johnson Mountain, began forming in the mid-Pleistocene. In addition, small fragments of the oceanic and continental lithosphere called terranes created the North Cascades about 50 million years ago.

During the Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris. The U-shaped cross section of the river valleys is a result of recent glaciation. Uplift and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the North Cascades area.

Climate

Johnson Mountain is located in the marine west coast climate zone of western North America. Most weather fronts originating in the Pacific Ocean travel northeast toward the Cascade Mountains. As fronts approach the Cascades, they are forced upward by the peaks (orographic lift), causing them to drop their moisture in the form of rain or snowfall onto the Cascades. As a result, the west side of the North Cascades experiences high precipitation, especially during the winter months in the form of snowfall. Because of maritime influence, snow tends to be wet and heavy, resulting in high avalanche danger. 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. Due to its temperate climate and proximity to the Pacific Ocean, areas west of the Cascade Crest very rarely experience temperatures below 0 °F (−18 °C) or above 80 °F (27 °C).

Gallery

• 
  Johnson Mountain and Blue Lake seen from Blue Mountain
• 
  North aspect

See also

• Geography of the North Cascades