| North Big Bosom Butte | |
|---|---|
 North Big Bosom Butte, circa 1966 | |
| Highest point | |
| Elevation | 6,384 ft (1,946 m)[1] |
| Prominence | 824 ft (251 m)[1] |
| Parent peak | South Big Bosom Butte (6,521 ft)[2] |
| Isolation | 0.58 mi (0.93 km)[2] |
| Coordinates | 48°57′34″N121°35′17″W / 48.959511°N 121.587968°W /48.959511; -121.587968[1] |
| Geography | |
  North Big Bosom Butte Location in Washington Show map of Washington (state) North Big Bosom Butte North Big Bosom Butte (the United States) Show map of the United States | |
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| Interactive map of North Big Bosom Butte | |
| Country | United States |
| State | Washington |
| County | Whatcom |
| Protected area | Mount Baker Wilderness |
| Parent range | Cascade Range North Cascades Skagit Range |
| Topo map | USGSMount Sefrit |
| Geology | |
| Rock type | breccia |
| Climbing | |
| First ascent | 1984 |
North Big Bosom Butte is a 6,384-foot (1,946-metre) mountain summit located inWhatcom County ofWashington state.[1]
North Big Bosom Butte is part of theSkagit Range, which is a subset of theNorth Cascades. It is situated 2.5 miles south of theCanada–United States border in theMount Baker Wilderness, on land managed byMount Baker-Snoqualmie National Forest. Its nearest higher neighbor is South Big Bosom Butte 0.6 mi (0.97 km) to the south,Mount Larrabee is three miles to the northwest, andPocket Peak is set 2.5 mi (4.0 km) to the northeast.[1] Precipitationrunoff from this mountain drains into Silesia Creek, which is a tributary of theChilliwack River.Topographic relief is significant as the summit rises 3,900 feet (1,200 meters) above the creek in one mile.
The Big Bosom Buttes were named by geologist Rowland Tabor, who with Doug McKeever, made the first ascent of the south butte in 1967. Surveyors made a helicopter landing on the north butte prior to 1955, but thefirst ascent of the north butte was made September 28, 1984, by John Roper and Mark Allaback.[3]
North Big Bosom Butte is located in themarine west coast climate zone of western North America.[4]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 (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.[4] Because ofmaritime influence, snow tends to be wet and heavy, resulting in highavalanche danger.[4] 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.[4] 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).[4] The months July through September offer the most favorable weather for viewing or climbing this peak.
The butte is made up of volcanic breccia of the Hannegan Pass Volcanics.[5] The North Cascades features some of the most rugged topography in theCascade Range with craggy peaks, 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.[6] With theNorth American Plate overriding thePacific Plate, episodes ofvolcanic igneous activity persisted.[6] The peak hasits own surrounding extinct caldera. In addition, small fragments of theoceanic andcontinental lithosphere calledterranes created theNorth Cascades about 50 million years ago.[6]
During thePleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris.[6] 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.
