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Mount Bachelor's Summit

The summit of Mount Bachelor is composed of numerous vents that erupted short, blocky basaltic-andesite lava flows. The summit vents and plugs exposed in the headwall of the cirque on the northeast side of the summit and are arrayed in a northwest-southeast-trending cluster that forms an elongate summit ridge. Near-vent tephra falls are scarce, which suggests that the most of the summit cone was built by lava flows, with minor explosive activity. From the summit of Mount Bachelor, a visitor can look south and see the extent of the volcanic chain as a line of volcanic events as far as Lookout Mountain.