| Gamma Peak | |
| Elevation Ft: | 7005 |
| Elevation Ref: | [1] |
| Prominence Ft: | 456 |
| Prominence Ref: | [2] |
| Isolation Mi: | 0.96 |
| Parent Peak: | Glacier Peak (10,549 ft)[3] |
| Map: | Washington#USA |
| Country: | United States |
| State: | Washington |
| Region: | Snohomish |
| Region Type: | County |
| Part Type: | Protected area |
| Part: | Glacier Peak Wilderness |
| Range: | Cascade Range North Cascades |
| Coordinates: | 48.1415°N -121.071°W |
| Topo: | USGS Gamma Peak |
| Volcanic Arc: | Cascade Volcanic Arc |
| Rock: | Andesite |
| Age: | Quaternary |
Gamma Peak is a 7005abbr=offNaNabbr=off summit in Snohomish County, Washington, United States.
Gamma Peak is located 25miles east-southeast of Darrington in the heart of the Glacier Peak Wilderness on land managed by Mount Baker-Snoqualmie National Forest. It is set 3miles northeast of Glacier Peak in the North Cascades. Precipitation runoff from the peak drains into Gamma and Dusty creeks which are tributaries of the Suiattle River. Topographic relief is significant as the summit rises 3950abbr=offNaNabbr=off above the Suiattle River in 3miles. The approach to the remote peak is via the Gamma Ridge Trail which starts in the upper Suiattle Valley near the Pacific Crest Trail. The summit provides one of the finest views in this part of the Glacier Peak Wilderness.[4] The mountain's toponym was officially adopted in 1963 by the United States Board on Geographic Names.[1]
Subduction and tectonic activity in the area began during the late cretaceous period, about . The area was previously an oceanic environment, consisting mainly of sedimentary and volcanic rocks.[5] Extensive volcanic activity began to take place in the oligocene, about .[6] However, mountain building in the area did not begin until the Miocene, approximately .[5] Glacier Peak, a stratovolcano that is southwest of Gamma Peak, began forming in the mid-Pleistocene.[5] Gamma Peak is composed of Quaternary andesite of the volcanic lava flows from Glacier Peak.[7]
Throughout the ice age, the North Cascades were mostly covered in thick glaciers, extending to near Puget Sound. Glaciation was most prevalent approximately, and most valleys were ice-free by .[5] As a result, valleys in the area are deep and U-shaped, and mountains tend to be rocky, with steep slopes and narrow summits.
Gamma Peak is located in the marine west coast climate zone of western North America.[5] Most weather fronts originating in the Pacific Ocean travel northeast toward the Cascade Mountains. As fronts approach the North 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.[5] Because of maritime influence, snow tends to be wet and heavy, resulting in high avalanche danger.[5] 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.[5] Due to its temperate climate and proximity to the Pacific Ocean, areas west of the Cascade Crest very rarely experience temperatures below 0°F or above 80°F.[5]