• Erosion may have removed the basal rock or sediment, leaving the boulder exposed
• The rock may have been transported from an ice sheet and was left exposed when the ice retreated—this is more accurately called a glacial erratic
• The rock may have been transported and placed at the location from a catastrophic geologic process, such as:
• Through a rockfall
• From a volcanic eruption, which results in lava bombs
• From a cataclysmic flood, such as a glacial lake outburst flood

See also

• Glacial erratic
• Hoodoo (geology)