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Rear-arc basalt lava outcrop

Detailed Description

A 3-4m (10-12 ft) high outcrop of basalt lava, part of a broader lava flow. These flows were erupted about 300,000 years ago following basalt dike intrusions in a rear-arc region of northern California. The eruptions of three of these flows are thought to have taken place within several hundred years of each other.


Public Domain.