Olallie Butte

Olallie Butte is a steep-sided shield volcano in the Cascade Range of the northern part of the U.S. state of Oregon. It is the largest volcano and highest point in the 50-mile distance between Mount Hood and Mount Jefferson. Located just outside the Olallie Scenic Area, it is surrounded by more than 200 lakes and ponds fed by runoff, precipitation, and underground seepage, which are popular spots for fishing, boating, and swimming. The butte forms a prominent feature in the Mount Jefferson region and is usually covered with snow during the winter and spring seasons.

Part of a stretch of shield volcanoes in Oregon with an unusually low elevation, meaning they have undergone less erosion over time than surrounding volcanic centers, Olallie has been excavated by glacial erosion on its northeastern flank. Its central volcanic plug has also been exposed. Comparisons of its morphology with Mount Jefferson suggest an age for the butte between 70,000 and 100,000 years; there is no evidence that it has erupted within the past 25,000 years. Olallie Butte has a steep, conical shape that serves as a transitional morphology between steep, mafic volcanoes like Mount McLoughlin and Mount Thielsen and flatter, mafic shields. It is made of basaltic andesite.

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