Mission Mountains

The Mission Mountains or Mission Range are a range of the Rocky Mountains located in northwestern Montana in the United States. They lie chiefly in Lake County and Missoula County and are south and east of Flathead Lake and west of the Swan Range. On the east side of the range is the Swan River Valley and on the west side the Mission Valley. The highest point in the Mission Mountains is McDonald Peak at . The range is named for its proximity to the Jesuit St. Ignatius Mission, established in the mid-19th century in what is today St. Ignatius, Montana. Geology The Mission Mountains are composed largely of what is called "Belt Rock" from the Belt Supergroup. The sedimentary rocks in this group formed between 1.47 and 1.4 billion years ago in the Belt Basin. The roughly circular basin collected sediments from surrounding areas for millions of years. The basin was eventually buried and later re-exposed through the collision of several tectonic plates around 80 million years ago.